U.S. patent application number 16/730753 was filed with the patent office on 2020-05-07 for electronic compliance system and associated methods.
This patent application is currently assigned to etectRx, Inc.. The applicant listed for this patent is etectRx, Inc.. Invention is credited to Eric Buffkin, Neil Euliano, Glen Flores, Brent Arnold Myers.
Application Number | 20200143926 16/730753 |
Document ID | / |
Family ID | 69057340 |
Filed Date | 2020-05-07 |
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United States Patent
Application |
20200143926 |
Kind Code |
A1 |
Euliano; Neil ; et
al. |
May 7, 2020 |
ELECTRONIC COMPLIANCE SYSTEM AND ASSOCIATED METHODS
Abstract
An electronic drug compliance monitoring system and associated
methods utilize a pill having an electronic transmission capability
and external means for receiving that transmission to sense the
presence of the pill in the patient's body or digestive tract.
Inventors: |
Euliano; Neil; (Gainesville,
FL) ; Buffkin; Eric; (Newberry, FL) ; Myers;
Brent Arnold; (Palm Bay, FL) ; Flores; Glen;
(Gainesville, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
etectRx, Inc. |
Gainesville |
FL |
US |
|
|
Assignee: |
etectRx, Inc.
Gainesville
FL
|
Family ID: |
69057340 |
Appl. No.: |
16/730753 |
Filed: |
December 30, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14573315 |
Dec 17, 2014 |
10521561 |
|
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16730753 |
|
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61917037 |
Dec 17, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/14503 20130101;
G16H 40/63 20180101; G16H 40/67 20180101; A61M 31/002 20130101;
A61B 5/4833 20130101; A61B 5/4839 20130101; A61B 5/01 20130101;
G06F 19/3462 20130101; A61B 5/14539 20130101; A61B 5/065 20130101;
A61B 5/14507 20130101; G16H 20/10 20180101; A61B 2560/0214
20130101; A61B 5/073 20130101; A61B 5/0402 20130101 |
International
Class: |
G16H 20/10 20180101
G16H020/10; A61B 5/00 20060101 A61B005/00; A61B 5/07 20060101
A61B005/07; G16H 40/67 20180101 G16H040/67 |
Claims
1. An electronic drug compliance monitoring system comprising: a
pill having an electronic transmission capability; and external
means for receiving that transmission to sense the presence of the
pill in the patient's body or digestive tract.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/917,037, filed on Dec. 17, 2013, the
contents of which are herein incorporated by reference in their
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to electronic systems and
methods for monitoring medication compliance.
BACKGROUND
[0003] Non-compliance of patients with drug regimens prescribed by
physicians can cause a multiplicity of problems, including negative
patient outcomes, higher healthcare costs and an increased risk of
the spread of communicable diseases. Compliance monitoring is also
critical in, for example, pharmaceutical clinical trials,
geriatrics and mental health/addiction medicine. Poor medication
compliance has a significant negative impact on patients,
pharmaceutical manufacturers and the healthcare system in general.
Non-compliant patients suffer from increased mortality, increased
recurrence of chronic conditions and increased hospital and nursing
home admissions. By some estimates, as much as 25% of all
healthcare costs could be avoided if patients reliably took their
prescribed medications.
[0004] Annual drug development spending has increased more than
twelve times in inflation-adjusted dollars over the past three
decades. Clinical trials consume a major portion of the development
time and costs of introducing a new drug into the market. Knowing
with certainty a patient's adherence significantly improves the
understanding of the results from a clinical trial in terms of
safety, efficacy, dose response relationship, pharmacodynamics,
side effects and other results. For instance, in a beta-blocker
heart attack trial the death rate was reported at 13.6% in subjects
whose compliance was less than 75% compared to 5.6% in subjects
whose compliance was over 75%. None of the existing methods of
measuring adherence offer both a qualitative and a quantitative
measure with proof-positive detection of ingestion of the
medication. Accordingly, measuring medication regimen compliance
continues to be a major problem. The only statistical recourse is
to enroll large numbers of patients, which dramatically increases
the cost of clinical drug trials that in turn increases the cost of
the final marketed medication.
[0005] Compliance monitoring also provides significant benefits in
market areas where patient adherence to a drug therapy protocol is
vital to preventing or avoiding high-cost consequences for the
patient or community. Strict regimen adherence is important for
preventing emergence of drug-resistant strains of infectious
diseases that can occur when proper dosing schedules are not
followed. Such resistant strains result in increased transmission,
morbidity and mortality and are more expensive to treat or cure,
often by one or two orders of magnitude.
[0006] A traditional method of increasing compliance is direct
observance, but this is obviously difficult to administer and
impractical on a large scale. Other techniques include blood
sampling, urine sampling, biological marker detection,
self-reporting, pill counting, electronic monitoring and
prescription record review. These techniques are either invasive or
prone to tampering.
[0007] In vivo biotelemetry and monitoring have been used for
monitoring embedded oxygen, sensing glucose levels, fetal
monitoring and hormone measuring. Passive radio-frequency
identification (RFID) techniques have been suggested to provide
biotelemetry by including external sensors into existing commercial
systems. However, RFID was not designed to operate in vivo, and the
transmission of electromagnetic signals from embedded or internal
sensors is hampered by attenuation and reflections from the
body.
[0008] Therefore, it would be beneficial to provide an active
electronic device, system and method for non-invasively monitoring
drug compliance in a facile manner.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to an electronic drug
compliance monitoring system and associated methods that utilize a
pill having an electronic transmission capability and external
means for receiving that transmission to sense the presence of the
pill in the patient's body or digestive tract.
[0010] It is believed that the present invention has several
advantages over currently known methodologies. For example, the
monitor documents that the prescribed medication was actually
present in the digestive system, whereas not even directly observed
therapy can conclusively determine that the patient swallowed the
pill. The system can be used with medication dispensers, timers,
reminders, external communications, and database systems to create
a complete medication compliance monitoring system. Information
from the system can be used to enable rewards for compliance or
punishments for lack of compliance. The system provides factual
evidence of patient's compliance to the medication regimen,
knowledge that is critical, for example, to assessing the outcome
of a clinical trial including the systematic removal of
non-compliant subject data. Trials that pay subjects to participate
in clinical studies can corroborate compliance. Further, the system
permits remote patient monitoring whereby the monitor can be
integrated into a wireless system communicating directly with a
central database, reducing costs by minimizing required patient
monitoring/interaction by support staff. Finally, the system is
noninvasive and does not require the collection of a bodily fluid
to determine that the patient is complying with the medication
regimen.
[0011] The features that characterize the invention, both as to
organization and method of operation, together with further objects
and advantages, will be better understood from the following
description used in conjunction with the accompanying drawing. It
is to be expressly understood that the description and drawing are
for the purpose of illustration and is not intended as a definition
of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic diagram of the medication compliance
system of the present invention.
[0013] FIG. 2A is one embodiment of a capsule having a planar
substrate with an antenna and electronics wrapped about a portion
of the capsule.
[0014] FIG. 2B illustrates a capsule having a single-coil antenna
wrapped about a portion of its periphery.
[0015] FIG. 2C illustrates a capsule having a digestible coating on
its outer surface.
[0016] FIG. 3 is a schematic chart that illustrates the use of an
electronic capsule with a wristband reader that is in communication
with a cell phone, and which in turn can be used to forward
information to a data collection center.
[0017] FIG. 4 is a block diagram illustrating the tag electronics
and antenna fitted with an electronic pill or capsule like that
shown in FIGS. 1, 2A-2C and 3.
[0018] FIGS. 5A and 5B illustrate techniques used to mate an
electronic tag shown in FIGS. 1 and 3 with the inside surface of a
capsule (FIG. 5A) or the outer surface (FIG. 5B).
[0019] FIGS. 6A, 6B and 6C are schematic side views illustrating
the layers used to fabricate an electronic tag in accordance with
different embodiments of this invention.
[0020] FIG. 7 is a circuit diagram for an exemplary activation
switch circuit using a conductive sensor with a NMOSFET
transistor.
[0021] FIG. 8 is a circuit diagram for an exemplary deactivation
switch circuit using a MOSFET transistor.
[0022] FIG. 9 is a circuit diagram for an exemplary MOSFET
sensor-based bio-switch.
[0023] FIG. 10A is a top perspective view of an ingestible switch
in accordance with the present invention utilizing a hydrogel
circuit breaker.
[0024] FIG. 10B depicts the switch of FIG. 10A, with a swollen
hydrogel circuit breaker after exposure to gastrointestinal
fluids.
[0025] FIG. 11 is a schematic side view of a galvanic gastric
sensor for utilization with the electronic tag shown in FIGS. 1 and
3.
[0026] FIG. 12A is a summary of the results of testing of several
phosphate electrodes at different modes.
[0027] FIGS. 12B and 12C are coded charts depicting the results set
forth in FIG. 12A for a 20K Ohm load and a 1K Ohm,
respectively.
[0028] FIG. 13 is a block diagram illustrating the electronics
associated with the tag integrated circuit.
[0029] FIG. 14 is a block diagram illustrating the overall in-link
and out-link communications between the electronic tag taken
internally by a patient, and the external reader utilized to
communicate with the tag illustrating a specific example of
conductive transmissions from the reader to the tag at 4 MHz and
radiative out-link transmissions from the tag to the reader at 400
MHz by way of example.
[0030] FIG. 15 is a timing chart illustrating the periodic
transmissions from the reader to the tag and the data bursts from
the tag to the reader.
[0031] FIG. 16 is a chart depicting the content of the in-link
transmission from the reader to the tag.
[0032] FIG. 17 is a chart depicting the content of information
contained in the data bursts from the tag to the reader.
[0033] FIG. 18 depicts a timing chart for out-link transmissions
from multiple tags to the reader.
[0034] FIG. 19 is another timing diagram illustrating the operation
of the system of the present invention.
[0035] FIG. 20 is a block diagram illustrating further aspects of
the operation of the system.
[0036] FIGS. 21A and 21B are side views illustrating alternate
constructions for the electronic capsule to permit a portion of the
electronics to be carried within the capsule.
[0037] FIG. 22 depicts an alternate construction with the tag
partially within the capsule and partially exposed.
[0038] FIGS. 23 and 24A and 24B depict exemplary constructions of a
capsule with a tag in accordance with this invention.
[0039] FIG. 25 is an exploded illustration depicting, from left to
right, the attachment of an integrated circuit chip to the tag
connected to the low frequency and high frequency antenna areas,
and the wrapping of the tag about a capsule (right hand side).
[0040] FIG. 26 is a cross-sectional side view of the tag,
illustrating the various elements depicted in schematic form in
FIGS. 6A and 6B.
[0041] FIG. 27 sets forth representative dimensions of the capsule
and tag.
[0042] FIG. 28 is a top view of a wrist band reader feature shown
in FIG. 3.
[0043] FIG. 29 depicts a patch reader wearable by a patient.
[0044] FIG. 30 depicts a pill container having an on-board
reader.
[0045] FIG. 31 is a block diagram of the reader 19 in FIG. 1.
[0046] FIG. 32 is a schematic diagram of asynchronous burst
operation.
[0047] FIG. 33 is a schematic diagram of a reader receive
architecture.
[0048] FIG. 34 is a schematic diagram of the medication compliance
system where EKG is used to confirm the identity of the
patient.
[0049] FIG. 35 is a top perspective view of one-half of a galvanic
cell lead arrangement.
[0050] FIG. 36 is an exploded top perspective view of one-half of a
different galvanic cell lead arrangement.
[0051] FIG. 37 depicts a tag positioned inside a capsule body.
[0052] FIG. 38 depicts a tag inside a capsule cap.
[0053] FIG. 39 depicts a tag inside a pocket in the capsule.
[0054] FIG. 40 depicts a pocket in the capsule and a tag that fits
in the pocket.
[0055] FIG. 41 depicts a bi-leaf foldable tag and method for
inserting it into the capsule.
[0056] FIG. 42 depicts a quad-leaf foldable tag with an anode and
cathode on alternating leafs.
[0057] FIG. 43 depicts a star-shaped foldable tag.
[0058] FIG. 44 depicts a how star shaped foldable tag may be
inserted into a capsule.
[0059] FIG. 45 depicts a tri-fold tag with pin holes therein and a
corresponding placement rod.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0060] A description of the preferred embodiments of the present
invention will now be presented with reference to FIGS. 1-45.
[0061] Noting FIG. 1, a system 10 for monitoring medication
compliance in a patient 16 comprises an electronic sensor,
preferably in the form of an external wireless monitor or reader 11
that includes an RF transceiver 12 and one or more antennas 13. The
antenna 13 can be external or internal to the reader 11 and can be
implemented in a variety of ways as known in the art, including an
on-chip antenna or simple pads or electrical contacts that function
as an antenna. The reader 11 detects the presence of an electronic
pill 14 in, for example, the gastrointestinal (GI) tract of the
patient 16. As shown the electronic pill 14 has a tag 15 attached
to or part of the pill 14. For purposes of this disclosure, the
term "pill" can include a capsule or other form of medication
administration or testing. The system 10 is designed to detect the
pill 14 when located in the patient's mouth M, esophagus E, stomach
S, duodenum D, intestines (including the colon) I or rectum R.
[0062] With continued reference to FIG. 1, the system 10 includes a
tag 15 fixed with the pill 14, either internally or along the outer
surface, or both. After ingestion of the pill 14, the tag 15 is
made electronically active and begins communication with the
external reader 11. The external reader 11 in one embodiment is in
a housing 19 worn by or attached with the patient 16 so as to be
comfortable and easy to wear continuously to ensure it is always
with the patient.
[0063] The electronic pill 14 comprises an orally ingestible and
biocompatible drug-transporting device with embedded or attached
electronic circuits that communicates with the external wireless
reader 11. As described in greater detail below, the electronic
pill 14 uses, for example, a silicon-based integrated circuit
and/or other passive components such as coil antennae and
capacitors. The circuit can incorporate millions of transistors,
patterned through various semiconductor processing steps, to
provide an enormous amount of intelligence. For instance, the
electronic pill 14 can store a patient's medical history in
addition to detailed information about a drug being administered,
provide a unique identification number, and implement advanced
communication circuits and protocols to reliably transmit data to
the external wireless reader 11.
[0064] Turning now to FIG. 2A, the electronic pill 14 preferably
comprises a drug-transporting device, such as a capsule 17 that has
associated therewith the electronic tag 15. Noting FIG. 1, a signal
52 received by the reader 11 from the electronic circuit 30 after
ingestion of the capsule 17 is thus indicative of medication
compliance. The term "drug-transporting device" is not intended as
a limitation, and other compositions and devices for delivering
medication are intended to be subsumed hereinto as known in the
art. Alternatively, the capsule 17 may be devoid of medication to
serve as a placebo during a drug trial.
[0065] Referring again to FIG. 2A, the electronic components of the
electronic pill 14 are capable of wireless transmission and
reception over short distances (i.e., in the range of 20-30 cm).
The electronic components in the circuit 47 (i.e., antenna, power
source, and silicon chip), once hermetically sealed and packaged,
are small enough to fit either to the inside wall or on the outside
wall of the capsule 17. This level of miniaturization is feasible
owing to integration and circuit scaling trends associated with
standard CMOS technologies.
[0066] With continued reference to FIG. 2A, a small chip or other
electronic circuit 47 is attached to the substrate 15 as well. This
circuit 47 provides a great deal of functionality including but not
limited to two way communication and complex protocols, energy
harvesting (mechanical, electrical, etc), sensing of conditions
such as location of the tag, pH, chlorine content, detection of
physiologic signals, biometric identification, encryption, and
identification code storage and transmission.
[0067] Referring now to FIG. 3, the complete system is principally
composed of a data reader 111 and multiple tags 15 attached to
medication 14. Bidirectional data 50/52 is exchanged between the
reader 111 and the tag 15. The reader 111 probes the one or more
tags 15 inside the body 10 and coordinates the communication to
allow multiple ingested tags to communicate simultaneously,
sequentially, or in other ways to permit multiple communication
pathways. The tags 15 communicate their unique identification data
and whether they are in the GI tract. The reader 111 then provides
output data 58 to a user interface 54 such as a laptop or
smartphone enabling real-time upload 59 of medication events to a
remote database 60 or other location. The reader 111 receives
information from the user interface 54 via the channel 56
indicating medication regimen status such as the time of the next
scheduled medication event, confirmation of the event from the main
database, or other information from the user interface 54 or the
remote database or trial coordination center 60 via the wide area
network (cell or wifi network) channel 59. In another embodiment,
the user interface 54 and reader 111 are embedded into a single
device, either on or off the body.
[0068] The data link from the reader 111 to tag 15 is defined as
the "in-link" path 50. Preferentially, in-link data to the tag
includes synchronization, signaling, address, and tag configuration
information. The reader 111 preferentially transmits information by
way of differential metallic skin contacts. The in-link signal 50
passes through the body 10 and is sensed by the tag 15 through a
differential probe network.
[0069] The data link from the tag 15 to the reader 111 is defined
as the "out-link" path 52. Preferentially, the out-link data to the
reader includes GI sensing, pharmaceutical, adherence, signal
level, physiologic data, biometric identification data, and address
information. The out-link channel 52 is a radio frequency signal
traveling through both the body 10 and the free space between the
body and the antenna of the reader 111. A small antenna on the tag
15 radiates the out-link signal 52 which is received at the reader
111. The reader 111 is capable of receiving signals 52 from
multiple tags 15 simultaneously.
[0070] All of these components work together to complete a system
that can accurately detect a medication event, including the time
of ingestion, the dosage, and specific identification of the
medication and/or subject using the system. This information is
then used to verify critical compliance with drug therapy. This
data can also be used in combination with other patient data to
improve adherence and treatment outcomes.
[0071] The following sections describe the detailed construction of
the tag 15. Referring to FIG. 4, the tag 15 comprises a body
interface and antenna 203 that allows for the in-link 50 and
out-link 52 communication. The ingestion detection subsystem 208
utilizes the body interface and antenna system 203 to determine
when the medication actually resides in the body 10 and in
particular in the digestive tract M,E,S,D,I,R, and specifically
which portion of the digestive tract. A receive subsystem 204
implements the in-link 50 communication and interfaces between the
body interface and antenna subsystem 203 and a control subsystem
209. A transmission subsystem 206 implements the out-link 52
communication and interface between the control subsystem 209 and
the body interface and antenna subsystem 203. An energy harvesting
subsystem 205 captures energy from either the body interface 203 or
from the environment that the tag 15 resides in, for example the
motion or temperature of the device. The energy harvesting
subsystem 205 provides energy which is stored in an energy storage
system 207 and to the tag 15 in general to operate the components
and provide sufficient power for out-link 52 transmission. The
control subsystem 209 coordinates and controls the differing
components of the tag 15 and implements any communication protocol,
sensor measurements, maintains tag memory for various
identification information, and implements any other functionality
required by the tag 15. The tag 15 can be attached to a pill 14 or
capsule 17 in a variety of ways, either by being built into the
medication, build onto the medication, being printed onto the
medication, or by being attached onto the outside or inside of the
medication carrier (i.e. a capsule). In an exemplary embodiment,
the tag 15 is on a biocompatible substrate 45 that can be built in
high quantities and then later attached or built into a capsule 17,
for example.
[0072] Referring now to FIGS. 5A and 5B, in another embodiment of
the tag 43, the antenna 44 are printed on a flexible substrate 45
that is biodegradable and digestible, such as a flat sheet-like
material, and includes an electronic chip 47 mounted on the
substrate. This substrate 45 is then placed on or wrapped around
the capsule 46. Preferably, the substrate 45 should have sufficient
rigidity for manufacturing and attachment, be easily and safely
digested, be flexible for wrapping around a pill or capsule, and
withstand temperatures required for manufacturing and
sterilization.
[0073] There are relatively few materials for substrates 45 that
are both easily and safely digested and can also withstand
temperatures required for bonding the chips 47 to the antennae 44
(up to 190.degree. C.) or the sintering of metallic inks. In one
embodiment, an enteric coating commonly used in colonic-targeted
drug release, is utilized to create a flat and flexible substrate
that meets these requirements and has been used in prototype
tags.
[0074] Enteric coatings are commercial materials with good
flexibility and proven biocompatibility. They are currently used in
aspirin, acetomenophin and other drugs that upset the stomach, as
they resist disintegration at low pH. Enteric coatings usually
begin to disintegrate at a pH above 5.5 or higher, which is the
typical pH of the duodenum and small intestine. Enteric coatings
include but are not limited to
polymethacrylate-polymethylmethacrylate (PMA-PMMA) copolymers and
cellulose acetate phthalate (CAP), which are commercial coatings
under names of "Eudragit" and "Aquacoat CPD" that are readily
available as pre-mixed solutions.
[0075] Referring now to FIG. 6A, in another embodiment, the
substrate 45 of FIGS. 5A, B can be manufactured with a coated paper
to create a biocompatible coated paper substrate system 260 to
provide advantageous properties. A paper substrate 82 coated with a
coating 254 provides improved mechanical properties, increased
printing strength, reduced dissolution time, and allows for
alternative printing methods, while maintaining biocompatibility.
Enteric coated paper provides a smooth texture 256 for the paper 82
and allows for antenna patterns 266 to be easily transferred onto
it. The paper 82 also breaks up rapidly once the coating 254
dissolves. Preferentially, the paper 82 is coated on all sides, but
in some implementations coating only the top of the paper is
required. In addition, a biocompatible adhesive 252 is applied to
the bottom of the paper when the tag 15 will be applied to the
outside of the medication. When adhesive 252 is included, a
protective backing 258 is used to simplify handling and attachment
to the medication.
[0076] The biocompatible coated paper system 260 of FIG. 6A
addresses manufacturing problems of electroplating/electroetching
on biodegradable substrates. Preferentially, biocompatible paper 82
is a mixture of biodegradable materials distributed in impregnated
and/or on coated the paper in a number of ways. Paper 82 can be any
substance that can be used as a flexible and strong biocompatible
substrate in the dry state but weakens in the wet state. Rice
papers, pulp papers, plant-based fiber papers including linen
papers are all substrates that can be used with a biocompatible
material coating or impregnation. The paper 82 itself is also
biocompatible. The biocompatible substances 254 used for coating or
impregnating the paper alter the dissolution properties, thermal
properties, mechanical properties, biodegradation rates and other
properties of the paper 82. The biodegradable materials included in
the construction of the biodegradable substrate 260 allow for
digestion of the substrates 45 and prevents untoward effects such
as lodging in the stomach of the substrate or pill itself, as may
occur with non-degradable and smoothly-surfaced polymeric
substrates.
[0077] The substrates 45 allow for the placement of a metallic
trace for antennae 266, chips 47 or other electronics via
electro-plate, bonding, gluing, adhesive or printing. The antenna
266 may be covered in a protective coating 268 to prevent
digestion, protect the antenna from handling, and dielectrically
isolate the antenna from the environment. The paper 82 is
superficially coated with the biodegradable substance such as
polymethyl methacrylate-polymethacryalte, cellulose acetate
phthalate, poly lactic acid, poly glycolic acid, various sugars,
oils, waxes or proteins.
[0078] The biocompatible materials 254 added to the paper also
allow for increased stability of paper materials in more extreme
environments, including those of very high temperature and
humidity, preventing the tag 15 from warping or deforming (and
possibly fracturing the antenna 266). Referring to FIG. 6B, the
substrate 45 is coated in a multi-layer or patterned method with
multiple layers of coatings 254, 264 such that various portions of
the tag can be exposed or broken down in the body 16 at varying
times or locations. At different times or locations in the body,
different coatings may dissolve exposing different types or
portions of the antenna 266 or sensors to the body 16. These
varying conditions provide information to the system allowing for
determination of ingestion time or tag 15 location. Referring to
FIG. 6.C, a cross-sectional side view of an alternate form of the
system 260A, the coatings can be patterned such that different
portions of the paper 82 are coated with different coatings. This
multi-layer or multi-coated system 260A tracks the progress of the
substrates as they pass through the digestive tract M,E,S,D,I,R or
encounter different solutions in the body 16. In a preferred
embodiment, each coating 254, 264 is an Enteric coating that is
formulated to dissolve in specific areas of the human body 16. In
combination with a multi-level electronic sensor and in the form of
an electronic pill, the location of the medication is tracked
through the human body. As each layer of the substrate 254,264
dissolves in its pH or chemically sensitive environment, a new
electronic sensor, which by way of example can be a galvanic cell
is exposed. In addition to exposing different sensors or probes in
different portions of the body 16, the selective dissolution of the
coatings in different parts of the body 16 alters the transmission
properties of the antenna 266 or system 260A in general, thus
making the location of the tag 15 in the body detectable without
separate sensors.
[0079] Various bodily chemicals and even organisms (and their
respective chemicals) can cause the degradation of the materials
used with the systems 260 and 260A. Enzymes, hormones, cells (blood
cells), proteins, acids, ions, bacteria, and so forth can
contribute to the degradation of the substrates or any of the
substrate layers.
[0080] Furthermore, in another embodiment, the system 10 is
triggered to dissolve in the patient's body 16 in the presence of
both a bodily chemical and an external impulse for additional
control. For example, the sensitivity of chemical breakdown is
enhanced by the application of RF energy to the substrates 260,260A
(producing heat or otherwise) from an outside RF source.
[0081] The system 10 may also be loaded with various degradation
control chemicals that can delay or hasten degradation rates. This
is useful if the processing of substrate layers that require
extra-thick amounts of a certain layer to be mechanically stable or
if a layer requires another chemical in addition to the ones found
in the human body 16 to begin degrading appreciably.
[0082] Pills 14 or capsules 17 are typically printed with edible
inks of pharmaceutical grade to uniquely identify the product and
provide additional information such as company logo, brand name,
and dosage information. In accordance with this invention, these
edible inks are replaced with conductive and biocompatible silver
inks to pattern small antennas 266 (FIG. 6A), coils 41 (FIG. 2C) or
deposited conductive pattern 44 (FIGS. 5A, 5B) directly on the
capsule 14, 17. Other compositions known in the art are also
contemplated such as but not limited to carbon black, iron, gold,
copper, zinc, and conducting polymers.
[0083] Thus, by way of printing, etching, or electroplating,
miniature antennae 266 are made of silver, carbon black, copper, or
other biocompatible coatings. Silver, copper, zinc and other metals
are substantially biologically inert, and when ingested in small
amounts, are nontoxic to humans and pass through the body without
being absorbed into tissues. Furthermore, the conductivity of most
of these metals is very high, making them excellent conductors.
Therefore, the antenna 266 performance not only depends on physical
size constraints, but also on the total usable concentration of
conductive material.
[0084] Referring again to FIGS. 6A and 6B, it is preferred to
encapsulate the components of the tag with a coating 268 for
multiple reasons, including but not limited to: electrical
isolation from the conductive fluids of the GI-tract M,E,S,D,I,R,
prevention of dissolution or exposure to the body for safety, and
selective dissolution at different locations in the body 16. For
example, the coating 268 prevents contact with the body, limiting
exposure of the materials to the patient 16. Certain coatings can
be utilized that are pH or otherwise selectively dissolved in
different portions of the GI tract. In a preferred embodiment,
enteric coatings that do not dissolve until they reach the
intestine I or other locations, where very little digestion occurs.
This allows the material to break up before excretion but not leach
materials into the blood stream. It is also desirable to activate
the tagging system only after the patient has ingested the pill 14.
Once ingested, the pill 14 or capsules 17, 46 are exposed to
stomach acids that eat away coatings 268 on the surface of the
capsule 17, 46. Coatings 52 (or 268) may be applied or selectively
applied to cover parts of the tag or capsule/pill. In one
embodiment, these coatings 268 are applied selectively to cover
certain portions of the tag and capsule but allow other portions of
the tag and capsule to break down. This allows the tag to change
shape or break down in such a way that it easily passes through the
digestive tract while still protecting sensitive materials from
digestion.
[0085] In another embodiment, the conductive layers of the antenna
266 on the tag 15 are made by incorporating a metal that can
dissolve, such as iron filings under a temporary protective layer
268 such as polyglycolic acid or by incorporating particles that
are nontoxic by virtue of being non-absorbable (e.g., silver or
carbon). Degradation of the matrix releases particles that move
through the digestive system of the patient 16 without absorption.
Such particles are present above a percolation threshold for
conductive "contact" (within 1000 .ANG.), and reside in a
degradable matrix such as polylactic/glycolic acid or starch. The
degree of conductivity is adjusted by the degree of close contact
and by the number of contact points (volume fraction). Particles
that are not spherical can be added at lower levels to get good
conduction. Hence, graphitic carbon plates can reach a percolation
threshold at lower levels, and silver can be used as planar
particles as well.
[0086] In a preferred embodiment, the integrated circuit 47 is
encapsulated or coated in a protective coating such that it is not
exposed to the body 16 and its digestive process. Packaging
preferably does not interfere with the RF communication but
provides enough safety for human studies. Methods of use allow
access to the aqueous environment for sensors while still ensuring
safety.
[0087] Power sources for body-powered electronic pills should be
biocompatible, small in size with the appropriate form factor,
capable of delivering high power with good maximum discharge
current characteristics and low self-discharge, and provide long
calendar life. Referring again to FIG. 4, many techniques may be
used for harvesting power 205 and storing the power 207 within the
circuit 47 for use with the tag 15. For example, a capacitor can be
used to store the energy at block 207 owing to the short duration
of the active nature of these devices. In one embodiment, the
capacitor is embedded into the pill electronics and charged from
block 205 by a handheld device via a magnetic field or other
mechanism before being swallowed by the patient 16. The capacitor
holds this charge until activated by a triggering mechanism, such
as the dissolving of a specially coated switch by stomach acid.
[0088] In another embodiment of the energy harvesting block 205 in
FIG. 4, the chemical energy of the stomach contents is converted
into electrical energy. For instance, the chemical reaction between
the stomach acid and a zinc electrode oxidizes the zinc, creating
an electric current via a metal electrode making the return path.
In another embodiment, the system converts mechanical motion (e.g.,
peristaltic and other motion common in the digestive tract) into
electrical energy.
[0089] In yet another embodiment, the energy harvesting system 205
of FIG. 4, harvests the energy of the in-link channel 50, stores
the energy in block 207 and uses this energy to power the tag 15
and transmit data via the radiative out-link 52. Harvesting of the
energy from the reader's in-link 50 is sufficient to power the tag
15 and its transmission of the out-link channel 52. In all of these
embodiments, the tag 15 harvests the energy until it obtains
sufficient energy to transmit a signal to the external reader 11
along the out-link channel 52. As illustrated in FIG. 15, this
harvesting process typically is substantially longer than the
duration of the burst information sent out by the tag 15, thus
allowing for amplification of the out-link channel 52 with respect
to the instantaneous power harvested, for instance from the in-link
channel 50. For example, if the in-link channel 50 is harvested for
100 ms and the out-link burst of information is 1 ms in duration,
the out-link power transmission 52 may be 100 times larger than the
instantaneous power harvested by the pill 14 or capsule 17 from the
in-link signal 50.
[0090] An important aspect in successful detection of the ingested
electronic pills 14 or capsules 17, 46 is to positively identify
the origin of the transmission, that is, whether the pill or
capsule is transmitting from inside the patient's body 16.
Knowledge of transmission origin is necessary to detect a patient
who might intentionally spoof the system into registering a
positive compliance. Multiple methodologies can be implemented for
ingestion detection with element 208 (FIG. 4). Noting FIG. 17,
multiple techniques exist for "triggering" the system to respond
only after reaching the stomach. The trigger can be activated by
the dissolving of material that opens (or closes) a switch. The
trigger can be based on electrical, chemical, or mechanical
detection of stomach or GI tract contents (e.g., pH sensor, ISFET,
temperature sensor, three electrode electrochemical cell,
microelectro-mechanical systems (MEMS), microfluidics, miniaturized
or nanoscale lab-on-a-chip, biomarker targeting, biosensors,
optical sensor, sound transducers, bio- or chemi-luminescent
sensor, or the like). When spoofing is not an issue, the trigger
can be activated just before ingestion or by the reader 11.
Additionally, one also simultaneously measures changes in material
properties such as physical size (swelling), magnetism,
polarizability/polarization, phase (solid-solid, solid-liquid,
liquid-liquid, etc.), viscosity, chemical/molecular makeup, optical
clarity, thermal conduction, state of charge and so forth. For
example, the sensor may sense changes in the outer walls of a
capsule, such as temperature or conductivity before it comes in
contact with the outer environment.
[0091] The ingestion detection system using the galvanic gastric
sensor 284 (FIG. 11) with sensor 208 communicates with the control
subsystem 209 of FIG. 4. The control subsystem 209 is then either
programmed to process the data it receives to determine if the tag
15 is in the proper location, or passes the data through the
transmission subsystem 206 for analysis by the external components,
for example the reader 11 (FIG. 1) or 111, external device 54, or
central database system or healthcare provider 60 (FIG. 3). In
another embodiment, the tag 15 does not respond to queries from the
reader 111 or 11 until the ingestion detection system 208 indicates
that the tag 15 is in the proper location, such as the stomach
S.
[0092] Additionally, the presence of specific features in the
received signal from inside the body may be sufficient to determine
the transmission origin. For instance, signal strength in out-link
52 coming from inside the body 16 is lower compared with that from
outside the body due to attenuation from tissue, blood, and bones.
It is also reasonable to expect a shift in the resonant frequency
or a unique characteristic of the frequency spread or content when
a signal propagates through tissue, which is absent when the
transmission is outside the body 16.
[0093] Additional techniques for detecting the origin of the
transmission of tag 15 include:
[0094] The dynamics of pill motion in the esophagus E (e.g., speed
of pill travel, orientation of magnet, and path of travel) and or
stomach S may provide subtle discriminating differences between the
in-link signal 52 received from tag 15 inside the body 16 and a tag
15 that is outside the body 16. The peristaltic motion of the
esophagus and the tossing and turning in the stomach may produce
pill motion that affects the signals received due to the natural or
purposely modified directionality of the fields generated by tag
transmission. Additionally, there is a normal progression from
mouth M to esophagus E to stomach S that will produce a difference
in motions that must be obtained sequentially to validate the
location of the pill 14.
[0095] Transmission of unique codes based on a variety of potential
sensors attached to the tag 15. In one embodiment, body
temperature, pH, ECG or other physiologic sensors are included in
the ingestion detection system 208 and either processed or relayed
by the control system 209 to the transmission subsystem 206. The
control subsystem 209 can transmit either raw sensor back to the
reader 11 or 111 for analysis of the patterns, or process the data
itself and transmit back to the reader 11 (FIG. 1) or 111 (FIG. 3)
an indication of its location.
[0096] Ensuring that the tag 15 is only active inside the patient's
body 16. For instance, the tag 15 is inert when dispensed and is
activated upon contact with saliva and/or other bodily agent.
[0097] Alternatively, the tag 15 is activated outside the body 16,
prior to ingestion, and deactivated inside the body 16 after coming
in contact with bodily fluid.
[0098] The activation/deactivation process can be carried out
using, for example:
[0099] Selectively coated sensors that exhibit change in properties
in the presence of specific chemical compounds.
[0100] Biodegradable switches based on proteins that are broken
down when exposed to digestive enzymes in the stomach.
[0101] Unique GI fluid sensors based on the properties of the GI
fluid
[0102] One implementation strategy of a bio-switch is to interface
the conductive sensor with a transistor (e.g., MOSFET, FET, BJT,
etc.), as shown in FIG. 7. A conducting sensor in series with
resistor R1 acts as a simple resistor divider and provides the
necessary biasing voltage to the transistor gate. The output of the
bio-switch is taken from the transistor drain and fed to the enable
port of the RF transmitter (an RF transmitter is used as an
example, but can be any electronic device that requires
activation). A power source provides necessary power to drive the
transistor and activation voltage. When the bio-switch is outside
the body, the resistance of the conductive sensor is small compared
to R1; thus the activation voltage (VA) will be below the gate
threshold voltage. When the gate voltage is below the threshold,
the transistor is turned off and the voltage at output equals zero.
When the bio-switch comes in contact with a bodily fluid, select
chemical molecules will bind to the conductive sensor and increase
its resistance, thereby also increasing the activation voltage.
When the activation voltage increases beyond the gate threshold
voltage, the transistor turns on, and voltage at output equals that
of the battery. A large voltage at the output in turn enables the
RF transmitter and readies it for transmission.
[0103] An alternative implementation is shown in FIG. 8, where the
circuit configuration yields a deactivation circuit. When the
bio-switch is outside the body, the voltage at output equals that
of the battery; that is, the RF transmitter is enabled. When the
conductive sensor comes in contact with a bodily fluid, the
transistor is turned on and voltage at output equals zero, thereby
disabling the RF transmitter.
[0104] A bio-switch implementation using a conductive sensor is not
limited to the above examples. Variations in transistor type,
substrate type, biasing schemes, selection of power, etc., can
yield several different implementation options. An exemplary
concept here is the utilization of a conductive sensor to drive a
switching mechanism. In the above examples a battery was used to
drive the transistor and circuitry, but instead a charged capacitor
can easily replace the battery. The switch can also be used to
modify the frequency of the signal transmitted or detected
externally (e.g., changing the frequency response of the
pill/antenna). The capacitor can be charged before a pill is
dispensed or can be charged by RF induction as is done in RFID
techniques. One positive aspect of using a capacitor is that over
time the capacitor will discharge and the entire system will become
inert, meaning the subject must take the pill within a given time
frame, thereby increasing the robustness of the system to
spoofing.
[0105] Another implementation of the bio-switch is to use a MOSFET
e-nose sensor instead of a conductive sensor. A bio-switch with a
MOSFET e-nose sensor can be implemented with much simpler
supporting circuitry since the transistor does both sensing and
switching. An example is shown in FIG. 9. The resistor divider of
R1 and R2 provides a fixed activation voltage to the transistor
gate. When the bio-switch is outside the body, the activation
voltage is just below the gate threshold voltage; therefore, the
transistor is off. When the MOSFET sensor comes in contact with a
body fluid, a catalytic reaction takes place at the transistor gate
and changes the channel conductivity; i.e., the gate threshold
voltage is lowered so that the activation voltage is now above the
threshold voltage. Therefore, the transistor turns on, and the
voltage at output equals that of the battery. Again, this
illustration is just one possible implementation scheme, and
variations can be constructed with different types of substrate
(e.g., n-type and p-type) and supporting circuitry.
[0106] An additional embodiment utilizes biodegradable switches
that undergo significant changes in conductivity when exposed to
the digestive enzymes of the stomach. One can mix a conductive
substance (e.g., carbon) with a non-conductive substance (e.g.,
protein). A conductive substance doped with a non-conductive
substance will tend to have lower conductivity (high resistance)
than a pure or even semi-doped material. When the doped material
comes in contact with digestive enzymes, the non-conducting
material is broken down or dissolved by the enzymes, leaving behind
just the conductive material. One possible switch implementation
can be based on a composition of carbon and albumin. The albumin
protein is broken down by pepsin, an enzyme that is naturally
present in the stomach. When the switch composition is devoid of
albumin, the conductivity of the switch increases and bridges a gap
in the circuit to complete the circuit. A number of possibilities
exist in selecting a conducting material and a protein.
Furthermore, it is also possible to incorporate multiple
non-conducting materials to yield switches that are extremely
selective to activation.
[0107] In the embodiment shown in FIG. 4, the in-link 50 signal is
used for energy harvesting 205 and is sufficiently low in frequency
such that most of the energy is transferred conductively through
the body of the patient 11. Thus, the tag 15 is only easily powered
when the tag 15 is in contact with the body of the patient 11 since
the in-link signal is significantly attenuated in the air. As such,
the tag 15 will not respond to queries from the reader 11 until
such time as the pill is being touched or ingested by the patient
11. Similarly, synchronization signals from the in-link 50 are used
by the tag 15 to modify the timing of the out-link 52 such that the
reader will not detect the signal unless the out-link 52 is timed
appropriately. When the in-link 50 is directly injected into the
body, it can be limited to only propagate through the body, thus
only tags 15 inside the body will respond properly to the reader.
This provides a level of spoofing prevention with virtually no
additional complexity added to the system.
[0108] Noting FIGS. 10A and 10B, in order to ensure that the pill
is ingested, the antenna system can be disabled by electrically
"shorting" the antenna through the use of an ingestible switch 90
that contains a circuit breaker 92 that becomes modified in the
presence of gastric juice. An embodiment of this concept includes a
method of breaking a circuit via the swelling of the breaker
material in the presence of stomach fluid. The switch 90 comprises
a thin layer of hydrogel 92 partially coated with a conductive
trace 94 such as metal flake or micro-thin metal foil. When the
hydrogel is exposed to low pH liquid, it swells to about sixteen
times its normal size and breaks the conductive trace 94. This
mixture is then coated with an albumin-based layer that will
prevent exposure of the hydrogel to fluids until the albumin is
selectively broken down in the GI tract by either pepsin or typsin.
The preferred mechanism for deactivating the system using an
ingestible switch 90 is to electrically connect the two pads of an
antenna 13, creating an electrical "short". The lower the
resistance, the more power is diverted from the signaling antenna.
By way of example, a five ohm resistance is sufficient to reduce
the input power from the antenna by 95+%. A resistance of 10K ohms
will reduce the input power to the signaling chip by only 10% or
less. In the case where the in-link 50 is separate from the
out-link 52, either antenna can be shorted by this technique,
essentially crippling the tag 15. The preferred embodiment is to
short the in-link antenna in a system that utilizes the in-link to
power the system.
[0109] Sensor such as pH sensors and other chemical sensors are
fairly complex devices. Noting FIG. 11, to avoid a requirement to
embed such a complex device into the tag 15 or integrated circuit
20, the preferred embodiment of a gastric sensor 208 utilizes a
galvanic couple 208 that is placed in various bodily fluids
(stomach fluid, esophageal fluid, GI fluid, etc.) to create a
measurable change in electrical properties such as current,
voltage, and/or resistance and allow digestible electronics to
evaluate the location of a tag 15 in the human body 16. In one
embodiment, the sensor 208 senses changes in the outer walls of a
pill 14, such as temperature or conductivity before it comes in
contact with the outer environment. In the preferred embodiment,
the galvanic couple can provide discrimination of location as well
as providing electrical power to the system. The ingestion
detection system 208 on the tag 15 works either outside or inside a
pill 14. Inside the pill, the detection system 208 operates when
the GI fluids permeate the pill or dissolve any external layers.
The tag 15 begins generating power and voltage as soon as it is
wetted by ingestion and allows the tag 15 to begin communicating
with the reader 111. As the tag moves through the GI tract
M,E,S,D,I,R, the sensor or voltage information is communicated or
processed by the control logic 209 such that location information
can be determined by the reader 111 or other external system. FIG.
11 shows the GI sensor/energy cell connected to control logic 208.
The GI sensor requires two electrodes for operation and one or both
of these electrodes may also function as antennas. In the preferred
embodiment, one of the electrodes for the GI sensor comprises a
small strip of metallic zinc while the second electrode consists of
a specially coated silver electrode that is shared with the in-link
antenna.
[0110] In one embodiment, the galvanic couple 284 is constructed of
two differing metals 280, 282 or compounds that, when placed in a
bath of any number of solutions, produces an electric voltage and
subsequent current and is measured by the control system 208.
Metals used for a galvanic gastric sensor 284 are transformed by a
number of chemical reactions to produce a new chemical compound.
The new compound changes the differential voltage. Upon immersion
in a target fluid, the compound transforms into a different
compound and accompanying the transformation is a change in
voltage. Other changes in the galvanic cell materials can be phase
transitions, state transitions, amount of the chemical compound
(causing a natural change in differential voltage based on the
degree of material available to sustain such a voltage), and other
materials transitions that cause a change in the electrical output
of the galvanic cell. In the preferred embodiment, the GI sensor
creates varying degrees of current or voltage depending on the
nature of the fluids in which it is immersed. Other signals such as
external voltage changes induced by the electrical activity of the
heart or muscles may also be detected on the galvanic couple 284.
Thus, the GI sensor not only gives true/false data about the
environment, but may also senses the
chemical/electrical/thermal/etc. makeup of the environment and give
a signal corresponding to the state.
[0111] The metals or compounds are connected to a measurement means
in the control logic 208 (FIG. 11) and can be a voltmeter,
potentiostat/galvanostat, electronic switch or other means to
measure or gauge the voltage and report if and/or when the target
electronic reading is reached in the target solution. If the sensor
284 is not in the target solution, the voltage will not change
appreciably as no chemical transformation will proceed. Thus, the
voltages or an indicator of location can be transmitted via the tag
15 to the reader 11 or 111 to confirm the location of the pill 14
or capsule 17, 46. Such chemicals transformations include silver
phosphate and other silver compounds, including silver chloride,
silver sulfate, silver carbonate, or even silver metal itself.
Transformation can occur on the anode or cathode of the galvanic
cell. In the preferred embodiment of FIG. 11, a silver phosphate
electrode 280 is attached to a zinc or magnesium electrode 282, and
the silver phosphate transforms to silver chloride and silver metal
while the zinc or magnesium oxidizes to metal or forms a compound
with anions in solution. Accompanying the silver materials
transformation is a voltage differential (from high-to-low or
low-to-high state). The voltage/current differential is affected by
the selection of the two metals or compounds (or mix thereof),
whereby a silver phosphate-zinc system differs in output
voltage/current from that of a silver-phosphate-copper or silver
sulfate-zinc system. Furthermore, a dissolvable or protective
coating 281, 283 may be applied to the electrodes 280,282 such that
the electrodes are not exposed to the fluid until a certain
external condition exists, such as when the tag 15 is exposed to
the high chlorine content of the stomach. Coatings on each
electrode 281, 283 can be the same or different, providing
flexibility in the voltages and currents produced in different
transit times and locations in the body 16.
[0112] FIG. 12A is a chart describing the voltages measured from
the silver phosphate electrode 280 of FIG. 11 formed by applying 9V
to a silver chloride electrode in KH2PO4 solution with a silver
electrode return path 282. The silver phosphate electrode 280 was
tested at loads of 20 kOhm and 1 kOhm. The charts in FIGS. 12A, 12B
and 12C show the time course of voltages of the electrodes with
differing amounts of phosphate (exposure time to the KH2PO4
solution), differing loads, and differing solutions. The gastric
sensor 284 has a substantially different voltage in HCl, the
primary component of stomach fluid, versus sulfuric acid
solution.
[0113] In alternate embodiments, the tag 15 is modified to include
sensors to measure various attributes of the pill's surroundings.
For instance, the tag 15 can have a pH monitor, temperature probe,
or other sensors 42 (FIG. 2B) to verify compliance. In addition, it
may be beneficial to use a system that can also provide a readout
of the in-link signal strength. This signal strength is beneficial
for optimizing the communication protocol dynamically as well as
providing potentially discriminating information relating to the
location of the tag 15.
[0114] In addition to determining when the pill 14 or capsule 17,
46 is ingested and where it resides, it is important to detect that
the pill is ingested by the appropriate person. As such, a variety
of biometrics are utilized to detect that the reader 11 or 111 and
pill 14 or capsule 17, 46 are located on or in the correct person
16.
[0115] In one embodiment, an electronic pill monitors physiologic
signals inside the body 16 that are typically difficult to mimic
outside the body. For example, the patient's electrocardiogram
(ECG) is detected and measured by the electrical contacts, galvanic
sensor, or antenna of the tag 15. The tag 15 either processes the
signal or passes the signal via the out-link 52 to the reader 11
for further processing. Detecting the presence of a valid ECG
signal indicates that the tag 15 is inside the body 16. Detection
of a periodic pulse between 30 and 120 BPM is sufficient to detect
that the tag 15 is inside the body. Furthermore, a wide variety of
parameters can be extracted from the physiologic signals detectable
inside the body 16. In a preferred embodiment, the processing
system (either in the tag 15, reader 11, or elsewhere downstream)
detects parameters of the electrical characteristics of signals
received inside the body 16 including but not limited to:
periodicity, amplitude, signal shape (including peak geometry,
relative height), and signal to noise ratio. In addition, the
signal detected inside the body can be transmitted to the reader 11
and verified against a preloaded signature of the ECG or other
physiologic signal recorded earlier, for example, during the
initial administration of the system 10. Additionally, the reader
11 can record the same signal outside the body 16 and ensure that
the tag 15 is in the same person 11 that is wearing the reader and
also checked against the stored signature. These features of the
ECG and other physiologic signals measured at the tag 15 or reader
11 are also capable of biometric identification.
[0116] In another embodiment, physiologic signals inside the body
16 are used to modify the timing of the out-link 52 signal. For
example, the out-link signal 52 can be timed such that it is sent a
prescribed time after the detection of the peak of the ECG signal.
Thus, if the reader 11 detects the same ECG external to the body
and determines that the out-link signal 52 timing is synced to the
physiologic signal, then the pill must be not only inside the body
16 but also inside the SAME body that the reader 11 is attached
to.
[0117] These physiologic features and their dynamic features
(changes in the signals over time) are useful to identify the
patient 16, ensure ingestion, or determine the location of the tag
15 in the digestive tract M,E,S,D,I,R. The dynamic features include
but are not limited to heart rate variability, changes in signal
strength as the tag moves through the body 16 and muscle activity
in different parts of the body. For example, the ECG will be quite
strong as the pill passes the heart in the esophagus E and then
gradually get weaker as it moves farther from the heart in the GI
tract S,D,I,R.
[0118] In an embodiment, the external reader 11 is used to monitor
and assess a given patient's 16 ECG output (periodicity, peak
geometry). This information is used for a first calibration step
and recorded as the baseline ECG output. The later measurement of
the ECG by the reader 11 validates that the same person is using
the reader. Additional, the measurement by the tag 15 can be
checked against this calibration to ensure that the proper person
is taking the medication. In this case, if either the medication or
the external reader is switched to a different person 16, the
results can be checked against the calibration data. Calibration
can take place in the presence of proper supervising personnel,
including doctors, nurses, etc., and the calibration can be locked
to those who either have calibration codes or calibration
devices.
[0119] These biometric capabilities can also be used to help guard
against improper medication (type or dose) being taken. Each tag 15
can be programmed to be taken by a specific patient. The patient
specificity will be recorded by certain physiologic signals that
can identify individual patients, such as parameters of the ECG.
The reader 11 or interface 54 can first be programmed to register
the kind and frequency of medication to be taken for a given
patient ECG. The reader 11 or interface 54 then alerts the patient
or proper personnel if the medication taken was given to the wrong
person (pill ECG does not match reader ECG) or if the medication
was taken at improper time intervals (over- or
under-medication).
[0120] Maximizing power efficiency is desirable to maximize the
reading distance between the reader 11 and the tag 15 as well as
power output and detectability. Advanced low-voltage and low-power
circuit design topologies and a suitable process technology are
required to achieve operation with small input power levels from
radiated electromagnetic fields.
[0121] Referring to FIG. 13, the preferred embodiment of the
integrated circuit 20 for the tag 15 includes: protocol logic 306
having a random bit generator for robust two-way communication and
control, data acquisition subsystem 304 and sensor 314 to determine
the strength of the in-link signal 50, in-link subsystem 302,
out-link subsystem 308, and energy harvesting and storage system
310. The IC 20 is designed with fallback operating modes, including
a chirp mode and a beacon mode. In the chirp mode, the protocol is
suspended and the IC 20 transmits data whenever it has sufficient
power from the energy harvesting and storage system 310. In beacon
mode, the IC 20 transmits a periodic burst pattern with no data
(bypassing all digital logic). In one embodiment, the energy
harvesting and storage system 310 extracts power from induced
currents generated from the external reader 11 via the in-link
subsystem 302 or directly via the in-link antennas 50. In a second
embodiment, a galvanic cell, GI sensor, thermocouple, or other
method of generating power from the digestive tract M,E,S,D,I,R or
motion through it provides primary or supplemental power via the
energy harvesting subsystem 310 to enable the IC 20. The out-link
subsystem 308 drives the out-link signal 52 under control of the
protocol logic and control subsystem 306. The protocol and control
system 306 contains all the logic to control the IC, the
communications protocol, the data acquisition, synchronization, and
data storage and output, including the preprogrammed information
about the medication, patient, study and other information.
Minimizing the power usage of all these subsystems and in
particular the out-link subsystem 308 is of utmost importance.
[0122] Preferably, the IC 20 is fabricated using industry standard
CMOS manufacturing processes in class 10 or better clean rooms. The
physical dimensions of the IC 20 are expected to be very small,
less than 1 mm.times.1 mm.times.0.1 mm. When affixed to the tag 15,
the IC 20 is encapsulated in biocompatible epoxy to cover any hard
edges and to prevent interaction between the IC 20 and the
patient's body 16. The preferred IC 20 is a custom designed
microchip that stores the medication information, reads the GI
sensor, and implements the signaling and communications protocol.
The IC is designed to operate with extremely low power and to
provide reliable deep in vivo communications.
[0123] In addition to integrated circuit implementations for the
various logic and systems of the tag 15, another embodiment
includes printed electronic circuits created with various inks
including metallic, dielectric, and organic materials. The creation
of complex printed electronics requires the creation of multilayer
electronic devices such as transistors and capacitors, silver
conductive ink and dielectric materials are typically loaded into
separate ink cartridges. For example, In the case of capacitors,
fabrication can be achieved by first printing a single line of
nanoparticles onto a substrate that is heated until the inks are
metalized. Next, a dielectric of polymer is printed directly over
the line. Finally, a second conductive line is printed
perpendicular to the original conductive line. In this way, the
overlapping cross-section of the two conductive lines--with a
dielectric between them-creates a capacitor whose capacitance is
defined by the overlap area and the dielectric material and
thickness Thus, if an antenna is printed simultaneously and
attached to each conductive line, a simple 3-step inking procedure
is enough to begin creating simple inductor-capacitor antennas that
can resonate at a tuned frequency.
[0124] Many generally recognized as safe (GRAS) materials are
available for use as dielectrics, for example
polytetrafluoroethylene (PTFE), polyimide (from precursors) and
PVP. In the preferred embodiment, enteric coatings are used as a
dielectric material.
[0125] The radiation efficiency of a typical loop antenna increases
with loop area and is inversely proportional to the excitation
signal wavelength. Since the loop area is limited, it is desirable
to operate at higher frequencies to improve the antenna efficiency.
In typical RF applications, operating at higher frequencies can
improve the aperture efficiencies of small antennae to maximize the
received power. However, in biological systems, the operating
frequency is a tradeoff between increased path loss in tissue and
antenna efficiency. Indeed, RF signal attenuation behavior of the
in-link 50 and out-link 52 in bodily fluids and body tissue to and
from an ingested tag 15 is complex and difficult to model.
[0126] The tag 15 may be coded with a variety of information
including but not limited to data about medication, the patient 16,
the reader 11, or the drug trial the patient is participating in.
Additionally, the tag 15 can have a unique ID that is utilized with
a database of other information tagged to each tag ID to obtain
similar information without storing it on the tag 15. Upon
detecting the tag 15, any of the readers 11, 111, 211 or 311 can
store a time-stamped reading of a medication event. If the tag 15
is not detected, failed compliance can be signaled, for example, to
the patient 16 and/or to a second party such as a health care
provider or other agency 54 via input and output signals 56,
58.
[0127] It is preferred that the communication between each reader
11, 111, 211 or 311 and the tag 15 provides two way communication,
with the communication from the reader to the tag 15 being
preferably through a conductive in-link channel 50 and the
communication from the tag 15 to the reader being preferably
through a radiative out-link channel 52. The in-link channel 50 is
preferentially in the range of 1-20 MHz; this frequency range
produces efficient data transfer from outside the body to deep
inside the body 16 and can travel through the body conductively,
requiring very small antennas or pads only to receive the signal.
Because the in-link transmissions 50 travel conductively, the
signaling attenuates very rapidly outside the body 16 thus
providing for increased privacy for the in-link channel 50. Skin
surface contacts with the reader, as readers 111, 211 and 311,
maximizes the efficiency of the in-link transmission 50 from the
reader. The in-link channel 50 communicates a variety of
information to the tag 15, including but not limited to querying
for the presence of the tag 15, turning the tag's transmitter on or
off, collision avoidance, and various other protocol-based
communications. The in-link channel 50 also provides
synchronization signals between the reader and tag 15.
Synchronization between the reader 11 and tag 15 are particularly
important when the out-link signal 52 is very small (as is expected
when coming from inside the body) and/or when the out-link signal
is transmitted in very short bursts for better energy
efficiency.
[0128] In an embodiment, the tag 15 is powered using the RF energy
received by its coil or antenna or in another embodiment where
power is generated by energy harvesting means. As described
previously, this power can be stored temporarily and then used to
transmit a pulse or signal to the reader 11. Storing the energy
internally in the tag 15 helps alleviate two distinct problems.
First, it allows for the storage and amplification of the
instantaneous power received from the in-link 50 or energy input
312 to create higher powered but shorter bursts of out-link
transmissions 52. Second, when transmitting into the body 16, the
external powering signal (in-link 50) creates significant noise
that may make detection of the out-link signal 52 from the tag 15
very difficult.
[0129] One method to create more detectable signals for out-link
signal 52 is to utilize different frequencies for power
transmission and data signaling. This allows the external receiver
12 of the reader 11 to be frequency-isolated from its transmitter.
A frequency selective filter may then remove the noise from the
transmitter to allow for high quality reception of the data signal.
Lower frequency signals typically have lower losses in the human
body. As such, the power transmission signal 50 may necessarily be
lower in frequency than the data transmission signal 52 which can
be much lower in power.
[0130] Another method involves the use of dual antennas on one or
both of the tag 15 and receiver 12; that is one antenna or set of
probes/contacts for the transmission/reception of the in-link or
power transmission, the other for transmission/reception of the
out-link signal.
[0131] As discussed in greater detail below with reference to FIGS.
15-18, another method involves the time multiplexing of the signals
such that the power transmission ceases during predefined time
periods to allow tag 15 to start transmitting data. The circuitry
of tag 15 can be designed to utilize this cessation of power
transmission as a marker to determine when to start transmitting
data. Additionally, that circuitry may store the power during the
"power cycle" for a period of time typically longer than the
transmission cycle to provide a power multiplication to improve the
signal strength of the data transmission.
[0132] It is preferred that the communications to and from the tag
15 and to and from the readers 11,111, . . . are protected,
encrypted, encoded, or made secure in a way to prevent
interpretation by other devices and have software and/or hardware
required to protect the data and support privacy or data security
requirements of the communication system.
[0133] Many of the tag 15 embodiments support IDs and other stored
data that can be transmitted back to the reader 11 via the out-link
channel 52. IDs and other data can be transmitted via pulsatile
signals (information in the pulse duration, pulse spacing, pulse
frequency, etc.) or via digital encoding. To increase
signal-to-noise ratio, it is preferable to have a transmit/receive
event wherein the tag 15 responds to a request from the reader 11
with a predetermined signal. This signal is repeated and then
synchronously averaged over multiple transmit/receive events to
produce a better signal-to-noise ratio. Synchronization of the
transmissions from and to the reader 11 and tag 15 also improves
the ability of the reader 11 to detect faint signals 52 from the
tag 15 in the body 16.
[0134] An embodiment of an efficient communication and protocol
approach is demonstrated in FIG. 14. The approach is based on a
unique communication path between the tag 15 and the associated
reader 11. The reader 11 transmits data to the tag 15 by way of the
conductive in-link 50 communication channel. The tag 15 transmits
data to the reader 11 through the out-link radiative channel 52. An
electromagnetic transmitter block 320 provides the interface to the
radiative channel 52 at the tag 15 and a corresponding reader RX
322 extracts the signal at the reader 11. A tag 15 for a patient 16
is linked directly to the patient reader 11 similar to a key and
lock. Only data with the proper key or data word are recognized by
the reader 11 as valid patient data. As an extra measure of
protection, the out-link TX carrier 320 is phase locked to the
reader in-link signal 50 to provide means for synchronization of
data. Phase lock also allows coherent detection of the tag data at
the reader 11, thereby enabling use of phase modulation and reduced
error rates. Since the in-link signal 50 is propagated by direct
body contact (in-link conductive channel), only the reader 11
attached to the patient's body 16 can properly demodulate the
return tag out-link 52 data. This feature makes external
eavesdropping of the data very difficult. Hence, this approach
enhances security of the data. As will be appreciated, this
communication protocol also allows several tags to be consumed and
data read without the need for individual tag identification bits,
thus reducing significantly the amount of data that needs to be
stored.
[0135] The protocol is composed of the communication link timing
and the associated in-link 50 and out-link 52 data fields. FIG. 15
depicts the relative communication link timing of the data for the
in-link 50 and out-link 52. The process begins with the reader 11
sending an FM modulated signal, or "in-link header" 330 to the tag
15 with information necessary for proper tag operation. The header
is sent periodically every T seconds. On ingestion, a random bit
generator in the circuit 20 for the tag 15 begins operation. On
completion of the in-link header field 330, the value of the random
bit generator is latched. This latched value is used to set the
time, t.sub.o at which the tag 15 responds to the reader 11 by
sending a data burst 332. The data burst 332 contains a subset of
the data stored on the tag 15 to be sent to the reader 11. Several
bursts 332 in sequence make up the full data transmission through
out-link 52. The latched random generator value becomes the pill ID
or address for this specific tag. Since the ID is random, each tag
swallowed will have a unique ID. As will be appreciated by those
skilled in the art, the algorithm may be as simple or complex as
necessary to assure no two tags randomly end up with the same
address. Each tag swallowed will send a pulse 332 delayed in time
from the end of the header 330 proportional to the value of the
random address. In this fashion, no two tags 15 can transmit at the
same time, thus preventing interference but also allowing multiple
ingestion of tags. Also, since the tag address is set randomly,
there is less need for special tag identification bits to be stored
on each tag, thus reducing significantly the number of bits of
memory required on the tag 15. This reduces cost and complexity of
the tag 15 significantly.
[0136] Referring to FIG. 16, a representative efficient in-link
data field 342 and corresponding definitions are shown. Field
selection can be used to improve the robustness of the
communications between the reader 11 and the tag 15. For example,
the field N defines the number of data bursts 332 that the tag 15
uses to define a single tag information bit. Thus, it is
appropriate to use a mechanism by which the system 10 assigns more
data bursts 332 per bit for situations where the signal to noise
ratio may be poor (very large patients for example). This allows
for more integration time and improved reliability. Such a system
is adaptable for broader utility.
[0137] Referring to FIG. 17, a representative efficient out-link
data field 352 is configured to allot two data bursts 332 for a
single bit 354. Depending on the total number of bits J of
information transmitted, N.times.J data bursts are generated. For
example, if the total number of bits 354 is J=16 and N=2, then 32
data bursts 332 are transmitted. As a further example of the
utility of this protocol, the reader 11 may be preprogrammed to
only accept out-link data with the proper patient ID. This along
with the fact that the data is coherently linked to the reader 11
essentially reduces the likelihood of data not associated with this
patient 16 being received as valid data.
[0138] FIG. 18 shows the timing for the case of three tags taken
together to further illustrate the efficiency of the protocol. Tag
1 362 transmits at a random slot after the in-link header 330 and
transmits multiple bursts 332 per bit 354. Similarly, Tag 2 364 and
Tag 3 366 transmit their multiburst per bit transmission in
different time slots after the in-link header 330.
[0139] As has been previously discussed, a communication network
utilizing a phase based modulation scheme is known to have
advantages of reduced bit error rate (BER) for the same
transmission power compared to simple modulation schemes such as
Amplitude Shift Keying (ASK). Since power is extremely limited in
in-vivo communication systems, minimizing BER is a challenge.
Implementing a phase-based modulation scheme requires that the
reader 11 be able to coherently demodulate the signal 52 for each
tag 15. This normally requires that the frequency stability of each
tag 15 be within a tight tolerance (20-40 ppm) to permit the reader
11 to phase lock and demodulate the received signal. Such frequency
tolerance requires that the tag 15 transmit frequency be based on a
crystal reference. Size and safety constraints prohibit the use of
crystals to generate the transmit signal for the tag 15. Further,
since the tag transmission burst is short in duration, there may be
issues in proper settling which may cause demodulation errors.
Another solution is for the reader 11 to have an independent
receiver for each tag 15 and preferably use a phase lock loop based
approach to lock to the incoming signal. There are issues with this
approach as well. First, the burst durations are short making the
design of such a receiver extremely difficult. Second, the tag 15
still requires some measure of frequency tolerance to assure
regulatory or system specifications are achieved. This may require
the need for tag frequency trimming which adds to the manufacturing
and test costs of each tag 15. Hence, a method is required to
eliminate the need for a tight frequency tolerance on the tag 15 as
well as a complex reader 11 receiver design.
[0140] A preferred approach takes advantage of the fact that the
reader 11 is connected via the conductive in-link 50 communication
channel to each tag 15. Hence, by using the reader 11 as the
initial frequency reference and locking each tag 15 to the
reference signal for reader 11, a self-synchronized coherent
communication system is realized. FIG. 14 illustrates this concept
in detail. First, the reader 11 generates a reference signal (shown
here for example with frequency of 4 MHz). This signal is passed to
the conductive channel 50 through an interface circuit 372 and
propagated to any tag 15 within the channel. At the same time, the
4 MHz reference 376 is frequency multiplied within the reader 11 to
the tag 15 burst frequency (400 MHz by way of example). This signal
is ultimately used to coherently demodulate data from any tag 15.
In the tag 15, the 4 MHz reference frequency is extracted,
amplified and passed to the input of a PLL demodulator and TX
carrier generation circuit (Tag PLL) 374. This circuit has several
modes of operation including the tag burst mode. During the tag
burst mode, the signal is frequency multiplied to the TX frequency
of 400 MHz. This signal is subsequently passed through the out-link
52 channel where it is extracted at the reader 11. The reader local
oscillator 378 derived from the original 4 MHz reference is used to
demodulate the received tag signal 52. The system is self coherent.
Thus, the tag 15 achieves a tight transmission frequency tolerance
by virtue of the phase lock loop 374 and does not require any
internal crystal reference.
[0141] Other advantages of this embodiment may be seen by referring
to FIG. 19. This figure shows the timing relationship between the
in-link 50 and out-link 52 burst signal and defines the three modes
of operation of the tag PLL 374 network. The in-link data is sent
at a periodic rate of T seconds, typically on the order of 1 ms. As
described earlier, the tag 15 responds some time later (less than 1
ms) with a TX burst. The TX burst also repeats at the same 1 ms
interval. A single period is expanded in FIG. 20 to further
highlight the modes of operation of the tag PLL. The tag PLL
operates continuously. During mode 0 382, the reader sends a fixed
reference signal of frequency Fref (4 MHz). The tag PLL locks to
this frequency and remains locked until progressing to mode 1 384.
During mode 1, the tag PLL remains locked; also during mode 1, the
reader 11 frequency modulates the 4 MHz reference signal with any
required information or configuration data for the tag 15. Since
the tag PLL is still locked to the reader signal, the modulated
data can directly be extracted from the VCO control voltage 375 on
the tag PLL. Hence, during mode 1 384, the tag PLL is acting as a
demodulation block. The tag PLL then returns to mode 0 382 and
stabilizes. Finally, during mode 2 386, the PLL is given the
command to frequency multiply the 4 MHz reference signal,
generating the 400 MHz TX burst signal. This is an efficient
realization using the same circuitry for both in-link demodulation
and TX carrier generation.
[0142] FIG. 20 shows more detail of the tag PLL 374. One key to its
operation is the dual frequency VCO 392. During modes 0 and 1, the
VCO 392 operates at 4 MHz. During mode 2 the VCO 392 is switched to
400 MHz (with VCO gain parameters changed accordingly) at the same
time a divide by N (100 for this example) is enabled within the
loop. The frequency of the phase detector 394 remains unchanged and
the loop dynamics remain the same. As a result the loop quickly
settles to a precise 400 MHz and the TX burst is transmitted. Once
the TX burst 332 is sent, the PLL 374 is returned to mode 0 and the
process repeats.
[0143] It will be appreciated by those skilled in the art that this
implementation has several advantages. Using fine lithography
integrated circuit technology, the power requirements for the VCO
392 during mode 0 and 1 are very minimal. Simple ring oscillator
approaches may be used for the VCO 392 requiring just a few
micro-amps of current. This allows the tag PLL 374 to operate
continuously which then permits a very frequency tolerant
transmission burst. The tag PLL 374 will stabilize with each
subsequent burst. The same circuitry is used for both transmit and
receive and area requirements are very small leading to a low cost
solution.
[0144] Wrapped tag embodiments are shown in FIGS. 5A and 5B. Noting
FIG. 5B, the wrapping process is typically partially around or
completely around the outer surface of capsule 46, soft gelcap, or
other medication carrying device as shown in FIG. 5B. The recent
invention includes the method of attaching the tag 43 to the inside
surface of the capsule 46 as shown in FIG. 5A.
[0145] Referring again to FIG. 5B, to avoid the accidental or
purposeful removal of the tag 43 from the outside of the capsule
46, prevent tampering, avoid damage to the tag 43, substrate 45,
chip 47, or antennas 44 from handling and environmental issues and
to increase the aesthetic appeal of capsules (and minimize patient
hesitation in taking an electronically-tagged medication), it is
prudent to conceal and protect all electronic devices, including
antenna 44 and chip 47, under a protective coating 48. The
protective coating 48 can be colored to match the capsule 46 or an
additional layer 42 can be included to cover the tag 43 or the
entire capsule 46 to further obscure the presence of the tag.
[0146] Now noting FIG. 5A, placing the tag 43 inside the capsule 46
obscures the tag from view, prevents tampering, and also provides
protection to the tag as the capsule 46 must dissolve or be
disassembled before the tag is exposed. Placing the tag 43 inside
the capsule 46 also maintains a minimal change in capsule volume,
and simplifies tag attachment and functionality. When the pill 14
is in the form of capsule 46 and the tag is inserted into the
capsule 46, the tag 43 operates similar to when the tag 43 is
placed on the outside of the pill. As the capsule 46 begins to
absorb fluids or the capsule begins to dissolve, the tag 43 will
come in contact with the GI fluids and begin to operate normally. A
tag 43 using leads that make contact with the interior wall of the
gelatin capsule 46 and activates upon wetting of the capsule can
react with the environment to identify location, chemistry, or
otherwise. The tag 43 can then use the gelatin capsule itself as a
protective system in non-aqueous environments. The diffusion time
of fluid through the capsule wall is the limiting factor for
detection of body fluids or transmission/reception of conductive
signaling within the body itself. To make contact with the outside
environment in an expedient manner, however, the receiving pads
must be in direct contact with the capsule as some pills swell
outwardly when exposed to fluid. Thus, for this approach an
adhesive for attaching the tag 43 to the inside wall of the capsule
46 is desirable.
[0147] In many cases, placing the tag 43 inside the capsule 46
works well. In some cases, the delay between ingestion and
activation of the sensor system on the tag 43 may be problematic.
Fitting the tag 43 with external exposed sensor or pads would be
advantageous for quick analysis of the body environment and for
advanced location discernment. Transit from mouth to stomach
typically takes place in less than 8 seconds, which is faster than
most gelatin capsules can absorb fluid and begin to break down.
Having an external lead or sensor minimizes this delay in sensing
time for an internally-placed tag 43. The number of pads that need
to be exposed can be as few as one, depending on configuration.
[0148] Referring to FIGS. 21A and B, a trace or foil 49 that runs
from inside the gelatin capsule to its exterior allows for
electronic transmission from within a capsule or power harvesting
from outside the capsule. Certain portions of the antennas or leads
remain exposed 79, 44 on the tag 43 allowing for electrical contact
between the tag on inside of the capsule and the interior-exterior
lead 49 on the capsule 43. The interior-exterior lead 49 is
preferably constructed such that an elongated pad 86,87 is included
to make contact with the antennas or leads 79,44,81 of the tag 43.
The tags 43 are constructed with coatings such that only the leads
or antennas that need to be connected to the interior-exterior
leads are exposed while all other electrical components and
antennas are coated in a protective and/or dielectric substance.
The elongated pads 79,87 and the design of the exposed areas of the
antennas or leads 44,79 allow for easy alignment of the tag 43 and
the internal/external leads 49. For example, in FIGS. 21A and 21B
each elongated pad 86,87 and exposed pad 44, 79 has a distinct
depth inside the capsule which provides for very simple alignment
of the tag 43 and leads 49. To make the interior-exterior
connection, the metal film 49 is thin enough to allow a 2-part
gelatin capsule to still snap together. The tag 43 itself, being
composed only of thin components (antenna, chip, substrate, etc.),
takes up a minimal amount of volume within the capsule 46 and
should not impair drug loading amounts.
[0149] Referring to FIG. 22, in one embodiment, the tag 43 is
inserted partially into the cap 110 of the capsule 46 and is
partially exposed as the capsule body 112 is inserted into the cap
110 but under the tag 43. The leads 44, 79 are thus exposed to the
outside of the capsule and can be made to appear innocuous.
Likewise, the tag 43 can be attached to the outside of the body 112
and partially covered once the cap 110 is placed on top of the
body/tag combination. Again, leaving leads 44,79 exposed for proper
sensing and/or power generation. Referring to the top portion of
FIG. 23, the tag 43 is inserted into the cap 110 and external leads
are printed, built into, or attached via a second printed antenna
substrate on the capsule body 112. When the cap 110 and tag 43
combination are inserted on top of the body 112 with external
antennas, 44,79, electrical contact is made between the internal
tag 43 and the external leads 44,79. This embodiment also allows
for "hot-swapping" of internal and external components of the tag
70. Different geometric designs of an external antenna can be
accommodated by a single or few internal tags by creating a system
that simply needs alignment of antennas with external traces. This
way, a number of antennas/sensor probes can be produced that have
specific applications (frequency, power transmission properties,
size, complexity) for a specific drug, creating a modular design
that can have certain unique or complex components placed on the
exterior of the capsule and maintain a communication pathway. This
embodiment also makes the process of creating multi-metal antennas
or sensors simpler as only small strips of material need be placed
on the outside of the capsule 70.
[0150] Referring to the bottom portion of FIG. 23, the tag 43 is
inserted into the body of the capsule 112 and the external leads
44, 79 are attached, built-into, or printed on the outside of the
capsule body 112. Vias, 87 or other methods are then used to
connect the tag 43 to the external leads 44,79.
[0151] FIGS. 24A and 24B illustrate an alternative embodiment where
the tag 43 substrate is built with elongated portions that contain
external antenna or lead components 44,79 such that when the tag 43
is inserted into one end of the capsule 46 the elongated portions
can be folded back and adhered to the outside of the capsule
46.
[0152] Referring to FIG. 25, in the preferred embodiment, the main
components of the tag 15 are a very small integrated circuit (IC)
47, a metal antenna 44, a gastrointestinal (GI) sensor/energy cell
composed of a specially coated GI sensor pad that doubles as an
in-link antenna 79 and a second metalic GI sensor pad 81, and a
substrate 45.
[0153] The substrate 45 is composed of a specially coated paper or
other inert material. Non-whitened, low-weight papers are non-toxic
and become softened in the GI tract M,E,S,D,I,R to allow for easy
passage without risk of lodging as it passes. In one embodiment,
these papers will then be coated with a pharmaceutical enteric
coating known as "Eudragit" or similar material that is inert and
biocompatible, which provides a smooth surface to allow printing of
antennas. Eudragit is also a pH-sensitive material that will
dissolve in the colon I, allowing the tag 15 to remain active long
enough to be detected before disintegrating.
[0154] The antennas 44,79 are printed on the substrate and
preferentially coated with Eudragit as described above to protect
the antenna and prevent interaction with the antenna materials
until the tag passes into the colon I where it begins to
disintegrate.
[0155] In one embodiment, the GI sensor/energy cell includes the
use of a zinc or magnesium electrode 81 and silver electrode 79
with special coatings as described previously. The GI sensor is
designed to restrict the bioavailability of the materials to levels
far below FDA, EPA, and/or recommended daily intakes. The simple GI
sensor produces induced voltages from the voltaic battery when
different metals interact with the acidic GI fluids. An analog to
digital converter within data acquisition block 304 in the chip 20
is used to uniquely detect the sensor's response to GI fluid.
[0156] FIGS. 25 and 26 show the preferred embodiment of the tag,
its size, and its approximate location of features. The tag 15
consists of four logical components: the in-link antenna system 79,
the GI sensor 85, the tag integrated circuit (IC) 47, and the
out-link TX antenna 44. The in-link antenna system 79 includes two
in-link 50 pads (body contact pads) that are 1-2 mm by 4 mm. The GI
sensor includes a pad 81 that is approximately 1 mm.times.5 mm. The
out-link antenna 44 utilizes the rest of the available space. The
tag IC 47 is shown in the inlay of the figure. On the right of FIG.
23 is a diagram of the tag 15 after it is wrapped around a
cylindrical object. The in-link antenna pads are separated by the
maximum available distance, which is 180 degrees across the capsule
once the tag is wrapped around it. The out-link antenna is
optimized for the required three dimensional geometry of the
capsule (or pill) after attachment. The tag 15 materials and
construction conforms to all safety, regulatory, and manufacturing
requirements. The physical structure of the tag 15 and its
relationship to a medication capsule is shown in FIG. 27. Target
Tag sizes are shown such as to conform to a size 0 capsule. Future
generations are expected to support smaller capsule geometries and
tablets.
[0157] To minimize the size and power requirements of the external
reader 11, in one embodiment it may not include the capabilities to
transmit information via a cell system, wi-fi, or other wireless
network. However, in another embodiment, the reader 11 can transmit
data to a standard cell phone, pager, or other device as shown in
FIG. 1 and as described below with reference to FIG. 3, to allow
for real-time updating of patient compliance and monitoring. Using
a two part reader system allows for a miniaturized on-body receiver
19 and a more powerful mobile device 54 with a more sophisticated
user interface for messaging and transmission to a global database.
In such a two-part reader system, an on-body reader 11 has two
communication systems, one 50, 52 to communicate with the tag 15
and one 56, 58 to communicate with the mobile device (for example a
bluetooth; see FIGS. 3 and 31 and discussion below). In such a
system, the mobile device only requires special software to operate
as both a standard mobile device and a front-end user interface and
wide area network (WAN) transmission interface.
[0158] The external reader 11 can be embodied in several forms. For
example, the reader can be the wristband 111 of FIG. 28, or the
patch 211 of FIG. 29 that can be adhered to the skin like a
bandage, an arm band, a handheld device or the like. Another format
is a pendant or similar device that hangs around the neck. In some
embodiments, it is advantageous for the reader to have contact with
the skin during a medication event. It is also advantageous to
design the reader to be readily available and/or worn to ensure it
is present with the patient 16 for all medication events. Another
form is the pill container 311 shown in FIG. 30 with contacts 313
on the bottle holder 311 for skin contact during the ingestion of
the medication. A minimal user interface exists on the bottle
holder 311 with a button to indicate ingestion has taken place 312
and an indicator 313 to determine when the pill was detected. The
patient 16 removes the medication from the container 311, ingests
it, presses button 312 and holds the pill container 311 against the
skin until the ingestion event is detected at the contacts 313 and
the indicator 314 confirms that the tag 15 was detected in the body
16. In other forms, the reader is also built into a mobile device
such as a cell phone, PDA, wrist watch, or into a memory card,
dongle, or other add-on device that can be attached or inserted
into a mobile unit. In yet another embodiment, the reader can be
built into a cell phone case, potentially borrowing power from the
cell phone.
[0159] Noting FIG. 31, each reader 11, 111, 211 and 311 has a small
user interface 227 that presents indicators of ingested medication
being detected and/or the capabilities to indicate when medication
should be ingested. The readers are disposable or reusable, or
contains portions that are disposable and reusable. The readers
also preferably contain means for storing the recorded data for
downloading via USB or other means directly to a PC or other
computing device. The readers are also preferentially rechargeable.
In addition, for those applications where the readers do not need
to be mobile, they may be built into a dongle or other means into a
standard computer or laptop.
[0160] Continuing with FIG. 31, the reader comprises several
RF/analog front-end components interconnected with a digital
processing core to handle the communication protocols. The body
interface or antenna subsystem 220 interfaces with the body 16 or
media surrounding the body (e.g. air). It contains the antenna and
or contact points to transmit the in-link 50 data to the tag 15 and
receive the out-link 52 data from the tag 15. In addition, the body
interface subsystem 220 includes the sensors, contacts, or antennas
necessary to acquire physiologic or biometric data required to
ensure the reader 11 is on the right patient 16 and the tag 15 has
been ingested by the right patient. The receive subsystem 221 and
transmission subsystem 222 contain the electronics to drive the
antennas and/or receive data from the body interface and antenna
subsystem 220. The uplink receive 225 and uplink transmit 226
subsystems transmit data to and from either a mobile device for
wide area communication or directly to a wide area communication
system such as cell phone, wifi, or paging networks. The protocol
and control subsystem 224 manages the communications of the
out-link 52, in-link 50, uplink 56, and downlink 58 transmissions,
controls the user interface 227 and processes all data coming in
and out of the reader 11. The user interface system 227 provides
information to the patient about when a tag 15 has been detected,
allows the patient 16 to initiate a manual detection, provides
indicators of when the pill 14 should be taken, and provides other
information to the patient.
[0161] The transmission subsystem 220 consists of a multiple
modules. The first module contains a high voltage modulator stage
with a programmable low frequency carrier to conductively couple RF
signals into the body 16. The supply voltage of the modulator can
be dynamically varied to superimpose in-link telemetry data to
communicate with the tag on the pill. Digital input signals will be
derived from the protocol and control subsystem 224 tasked to
handle communication protocols to and from the tag and also to and
from a uplink/downlink transceiver 225,226 that wirelessly
interconnects mobile devices to the reader 11. The second module is
a UHF receiver chipset used to demodulate out-link 52 data from the
tag 15. The receiver is used to downconvert the detected out-link
RF signals 52 for data extraction by the baseband processor.
Preferably, all communication protocols between reader 11, tag 15
and mobile devices 54 are be synchronized to a master clock
generation module to ensure proper timing control.
[0162] Additional adherence improvement is likely when the patient
16 is motivated to follow the prescribed regimen. By connecting the
patient with the medication, the pharmacodynamics (PD) and
pharmacokinetics (PK), dose/response data, and their own reaction
to the medications, patients become more interested in their
regimen and become more adherent. The software system is
preferentially implemented in a smart phone application that is
linked to the reader 11 and the information provided by the
uplink/downlink data. In a preferred embodiment, the software shows
estimated blood levels of the drug of interest based on the known
patient information and medical information stored in the system,
as well as the exact timing and doses of the medication taken by
the patient. The software shows the patients how missing doses or
improperly taking their medication affects their simulated blood
levels, drug effectiveness, and how it changes their physical
responses to the medication.
[0163] Other embodiments include personalized calendars that list
each medication and dosage listed under the following four time
periods: Morning, Noon, Evening, and Bedtime. If a patient does not
take their medicine, they are asked to write the reason. It also
lists any special instructions to help prevent adverse effects
resulting in decreased medication adherence. The software also
contains a list of abbreviated instructions on how to use and
monitor each drug so that the patient understands the benefit and
risk of each drug. The software also allows the pharmacist to enter
how many days late the patient comes to the pharmacy for a refill
of chronically taken medication. If the adherence rate is
unsatisfactory, the pharmacist is presented with various options on
how to enhance adherence through patient education programs
designed from well documented motivational interview
techniques.
[0164] The Personalized Medication Adherence Registry (PMAR) is a
mobile software system that receives medication adherence data from
the patient and device links, then presents it to the patient and
healthcare providers in an extremely quick and easy to understand
format. The largest group that will benefit from PMAR are those
patients taking multiple chronically administered medications that
are essential to wellness. Another important population are
patients who are receiving medications that create frequent or
severe adverse drug reactions (ADRs). Typical examples of
healthcare providers are all physicians, pharmacists, nurse
practitioners, physician assistants, clinical trial personnel, and
any other health related professions who advise, monitor or treat
patients with medications.
[0165] When patients visit their physician or other health care
providers, they are usually asked to produce a comprehensive,
up-to-date, and accurate list of all their medications including
the name of the drug, the dosage strength, and the directions for
use. This list can become extremely complex very quickly and
difficult to recall. This list is immensely valuable when a patient
is traveling and in an accident. It may be life saving if this
medication list can be produced as quickly as possible with all the
required details. Having an electronic copy immediately available
can save the patient time and money while improving their health
and possibly preventing an inappropriate drug related catastrophe.
A common example is when one of over 20 million Americans with
diabetes becomes extremely weak in a public place. If he/she has
recently taken his blood sugar lowering agent, a liquid with
concentrated sugar e.g. a soft drink or orange drink may save their
life. The patient must provide their username and password to allow
others access to this encrypted information. Since this protected
information resides on their cell phone, access to cellular service
is not required. A back-up of all this protected information can
also be accessed by the patient and any healthcare provider, family
member or close friend who has access.
[0166] If the patient has access to the Internet via their cell
phone or personal computer, they will be able to click a drug from
their drug list and be linked to drug-specific information in
Wikipedia. They will be reminded to print the information and have
it validated for its accuracy and personalized application to their
situation based upon various factors that are relevant, e.g., all
their existing disease stated, medication list, age, sex, weight,
diet, and exercise program.
[0167] The Reminder feature of PMAR provides a timely visual and
auditory notice to the patient via their mobile phone allowing the
customer to be alerted for each of their scheduled medications.
PMAR is easily customizable as to each patient's preference as to
how they are to be reminded and the sound/vibrate/visual
notification rules governing the reminder system. They can reminded
to take all their prescription medications (Rx's), OTCs, herbal
medications, and nutritional supplements.
[0168] PMAR will also remind the patient several days prior to
completing their medication that it is time to obtain a new refill
or if they are probably almost out of their OTC, herbal, and
nutrition supplement. This prevents one of the leading causes of
proper medication adherence. These reminders are based upon the
date of the last refill and whether they received a weekly,
monthly, or quarterly refill.
[0169] Although reminder systems are not uncommon, when coupled to
compliance monitoring systems, additional features become possible.
For example, if medications are not ingested when requested, a
series of reminders or alerts can be sent starting with the patient
and following up with family, care givers, doctors, pharmacists,
drug trial monitors and administrators. If necessary, the system or
support personnel can call or visit the patient to ensure that
there are no problems and that the patient is taking the medication
regularly.
[0170] In addition, the real-time recording of every ingestion
uniquely enables various advantageous patient reward systems that
can be included in PMAR. For example, when patient's take their
medication according to their regimen, they may be provided with
coupons for free or discounted services or products. These coupons
could be funded by any number of parties with a vested interest in
ensuring medication adherence, including the pharmacy, the
pharmaceutical company, the insurance company or government agency.
For children and young adults, gaming coupons or online money or
points for online games, music downloads, etc. can be provided for
good or improving adherence.
[0171] Other incentives or rewards can include currency, services
such as free airtime, text messages, or data from a cellular
provider, and discounts or credits towards the purchase of a
product or next refill of the medication. Because each dosage can
be individually verified as taken in real-time, currency or
discounts can be incrementally added directly to a bank account or
online account. The online account can be displayed on the user
interface or on a web page. Gifts can be delivered directly by an
online retailer automatically when the patient reaches a certain
compliance level. The medication of interest can include
prescription medicine, over the counter medicine, vitamins,
supplements, food item, or any other ingestible that can have a tag
attached to it.
[0172] When the patient is reminded to take their medication, one
of their options will be to choose from a list of common side
effects and ADRs to document if they have experienced a recent ADR
and if they stopped taking their medication secondary to the ADR.
This often happens without the pharmacist or physician being aware.
This will assist healthcare providers in determining the cause of
patient non-adherence and prompt them to possibly decrease the dose
or select an alternative medication. This feature alone can help
decrease many avoidable hospitalizations.
[0173] Referring again to FIG. 1, as an alternate to detection of
the pill in the gastrointestinal system, it is also possible to
detect a pill 30 as it passes through the esophagus E using a
sensor 32 designed to fit around the neck 33. Preferably, this
sensor 32 takes the form of a complete circle around the neck 33, a
partial, horseshoe-like enclosure, or a simple device held against
the neck 33. The sensor 32 detects all embodiments of the pill 30
described elsewhere as it passes through the esophagus E into the
stomach S. The embodiments in which the sensor 32 forms a semi- or
full circle around the neck 33 also improve the signal-to-noise
ratio over a sensor that is simply held in front of the patient.
There is also less dependence on digestive mechanisms, providing
less design restrictions on the pill itself.
[0174] The neck sensor operates in all the same ways as the
gastrointestinal reader 11, but also allows for other, possibly
advantageous, protocols. For the case in which multiple pills must
be detected, a protocol in which the patient takes one pill at a
time can be employed. In this approach, only one pill will occupy
the esophagus E at any time, which improves the sensor's capability
to identify and tally dosage.
[0175] A biometric identification aspect is now described with
reference to FIGS. 32-34. In some instances, it is important to
know that the electronic pill 14 is inside the body of the person
wearing the reader device 111. This may be accomplished by both the
pill 14 and reader 111 measuring a known physiologic signal and
communicating attributes of this signal between them. The knowledge
that the reader 111 and pill 14 devices are measuring the same
physiologic signal indicates that the pill 14 is inside the same
person that the reader 111 is attached to.
[0176] The pill 14 may include a compliance monitoring device (404)
attached or inside. This compliance monitoring device 404 measures
a biometric signal such as the patient's ECG 405 after being
ingested and sends a signal corresponding to the ECG signal 405 to
the reader 111 attached to the patient. The reader 111 also
measures the ECG signal 405 of the patient and can compare its
signal to that measured by the compliance monitoring device 404. If
the two signals match, the pill 14 is confirmed to have been
ingested by the person wearing the reader 111.
[0177] In order to reduce the amount of information that needs to
be transmitted, certain characteristics of the ECG signal are
calculated and transmitted between the pill 14 and reader 111. Many
characteristics are possible, but a preferred characteristic is the
timing of the peaks in the ECG signal 405. This timing, sometimes
called the R-R time because the peak of the ECG 405 is often
described by the letters QRS, can be easily calculated at both the
pill 14 and reader 111 and compared, without the need to transmit
the entire ECG signal 405. Other characteristics of the ECG that
can be measured include: heart rate, ratio of P to QRS or T to QRS
amplitudes, duration P-R or R-T timing, QRS duration, among
others.
[0178] In addition to ECG, other physiologic signals may be used,
including but not limited to breath rate, muscle activity, acoustic
information, and blood flow measurements such as pulse oximetry, or
body movements read with an accelerometer or similar sensors.
[0179] In certain communication schemes, synchronizing the
transmitter and receiver provides advantages including but not
limited to higher signal to noise ratios, lower power transmission,
and better reception. The use of the physiologic signal to
synchronize the in vivo and ex vivo transmitter and receiver
provides both a mechanism for synchronization and also ensuring
that only pills ingested by the person wearing the reader 111 are
detected. If a person other than the person wearing the reader 111
ingests the pill 14, the physiologic synchronization cannot take
place since each device will have a different synchronization
signal. Only if the same person who is wearing the ex vivo reader
111 also ingests the pill 14 can the two devices properly
synchronize. In addition to this advantage, synchronizing to the
physiologic signal prevents the need for either device to broadcast
a synchronization signal, thus saving power in the communication
system. In one embodiment, as described previously, instead of
transmitting the ECG or parameters of the ECG, the outlink signal
52 is timed relative to a feature of the ECG such as the peak of
the QRS. Thus, the reader 111 and pill 14 can only synchronize when
the ECG signal is measured in the same body, without the need to
actually transmit the parameters of the ECG.
[0180] Another use of monitoring the physiologic signal is
biometric identification. By measuring attributes of the ECG 405 or
other physiologic signal of the patient, identification of the
person actually wearing the reader 111 can be achieved. The
physiologic signal may be measured by the pill 14 or reader 111
when the device is first provisioned. Thus, the device records the
important attributes of the physiologic signal and then
continuously compares the attributes of the physiologic signal
throughout its use. If the attributes change significantly, this
indicates that the person wearing the reader 111 is probably not
the same as the person who was originally provisioned the reader
111. This prevents people from swapping readers 111 or having other
people take their pills 14 for them.
[0181] In one embodiment, principal component analysis (PCA) is
used for feature extraction from the vector of data points
representing a single pulse of ECG. For this algorithm, the
fiduciary points are projected with PCA into a subset of features.
For the classifier portion of the biometric signal, a linear model
is used to match the PCA features to each person. In experimental
trials, this method achieved an identification rate of 93% with ECG
data sets from 60 different people.
[0182] The algorithm averages the individual pulses and then
applies a similarity measure that compares the vector of PCA
features from one subject to the vector of PCA features of other
subjects. The similarity metric (for example mean squared error or
Mahalanobis distance) calculates the distance between the vector
under study and the average vectors from each subject in the
database. For example, individual beats are aggregated and pruned
for training the model. Pruning is determined by the similarity
between beats. The similarity is calculated as follows:
n .SIGMA. x i y i - .SIGMA. x i y i n .SIGMA. x i 2 - ( .SIGMA. x i
) 2 n .SIGMA. y i 2 - ( .SIGMA. y i ) 2 ##EQU00001##
[0183] This similarity measure is also used to determine patient
X's distance with respect to either patient Y or a model that
represents the world (averaged across all other patients) i.e. a
cohort vs World model. In experimental trials, this model was able
to correctly identify 98.67% of the patients (including the
multi-day recordings).
[0184] As known in the art, many other methods can be used to
compare the physiologic signals such as ECG to previously recorded
signals. For example hidden markov models, correlation, neural
networks, clustering, and other methods.
[0185] Multiple biometric methods can be used simultaneously. To
obtain a good ECG signal, the data must be collected near or across
the heart. Optical sensors on one arm or hand can detect blood flow
and thus heart rate, but good ECG signals on the arm/hand require
either both arms/hands or one arm/hand and a reference elsewhere on
the body. In one embodiment, both an ECG system as described
previously and a finger print system are used. In one
implementation, an armband/wristband style reader is used with a
fingerprint sensor. (PROBABLY NEED A FIGURE). On the top face of
the armband/wristband is a fingerprint sensor. The fingerprint
sensor is also connected to an electrode (typically metallic). On
the underside of the armband/wristband is a second electrode to
allow ECG collection during capture of the fingerprint, since the
subject is touching the electrode on top of the reader with one
hand and the electrode on the bottom of the reader with the other
hand/arm simultaneously. The electrode on the bottom of the reader
can also be used as an impedance monitor to detect when the reader
is removed. By detecting removal of the reader, the fingerprint may
only be required once as long as the reader is not removed.
Secondarily, the impedance monitor can be used with both the top
and bottom electrode to verify that the person swiping their
fingerprint is the same person who is wearing the device. The
impedance between one arm and the other hand/finger is much lower
than an open connection that would be detected if a person not
wearing the reader did a fingerprint scan.
[0186] The use of continuous data available on a reader 111 that is
worn for extended periods of time provides a methodology for a much
more robust biometric identification. Methods to remove noisy data
during motion or other artifacts while still matching only the
clean signals provides great flexibility in the identification
system. In addition, the ability to detect when the signals are
lost can be useful in determining when the reader 111 is removed
and replaced on the body. As long as the signal does not change
dramatically or cease to be collected, it can be assumed that the
same person is wearing the reader 111.
[0187] When multiple pills 14 are ingested it is desirable for the
reader 111 to be able to detect each device independently. In cases
where the pills 14 are not in communication or synchronized by some
other means, it is desirable to have a communication telemetry
system that may operate asynchronously. Pills 14 provide telemetry
data by sending amplitude based bursts of radio frequency (RF)
energy at a frequency of fc Hz. These bursts are separated by a
period of TB seconds. For multiple devices the frequency fc may be
different for each device, either by design or due to process
variations. Similarly, the period of bursts will be different for
each device.
[0188] Asynchronous operation may be used to assure a relationship
between the burst separation period and the burst frequency. The
reader 111 may then perform frequency analysis on the incoming
pulse stream and sift out the individual pieces of telemetry from
each communication device.
[0189] An example of this is illustrated in FIG. 32. An individual
communication device generates a burst separation and carrier
frequency from a common clock generator. By determining the burst
separation period at the reader 111, the burst frequency may be
calculated.
[0190] FIG. 33 shows a reader receive architecture which
accomplishes this. The input signal to the receiver includes bursts
from up to N individual communication devices. The bursts contain
information from each device 1 through N represented by signals S1,
S2, . . . . SN. The ensemble burst telemetry is down-converted and
filtered to a first Intermediate frequency, IF1. This signal is
digitized by the analog to digital converter (ADC). A Fast Fourier
Transform (FFT) is carried out which finds the periodicity of the
pulse period for each communication device. Because the pulse
period is directly related to the carrier frequency, this
information is binned and used to digitally control oscillator
blocks that generate local down conversion signals to bring each
individual in-vivo signal to baseband. The converted signal is
optimally filtered and passed to a signal processing block that
extracts the information signals S1 . . . SN.
[0191] An alternative approach is to use fixed oscillator signals
for c1 . . . cN and down-convert directly.
[0192] An example of a power source for the chip 47 is now
described with reference to FIGS. 35 and 36. Two forms of creating
one half of a galvanic cell on the backside of a semiconductor die
450 are presented here. The metalized sections are used as a power
source for the die 450 upon immersion of the device in a fluid and
when paired with an appropriate cathode/anode.
[0193] A metalized material section 452 connects the front side 454
of the die where the bond pads have been created to the typically
bare backside 456 of the die which is eventually metalized with the
appropriate cathode/anode material. In the example shown, the
backside is metalized with a magnesium film 458.
[0194] In FIG. 35, the metalized material section 452 is applied to
the side of the semiconductor die 450. This provides a conductive
pathway between the bond pads and the backside metallization, which
in this case is the magnesium film 458. This metalized material
section 452 may be deposited similarly to the backside
metallization or using conventional patterning techniques such as
lithography.
[0195] In FIG. 36, the metalized material section 452 is applied
through a hole that passes through the die 450. This also provides
a conductive pathway between the bond pads and the backside
metallization, which in this case is the magnesium film 458. The
hole is formed, for example, by etching.
[0196] While the examples in FIGS. 35 & 36 show only one
metallization (and therefore will need a cathode somewhere outside
of the die), an alternative embodiment includes both the cathode
and anode material deposited on the backside with a physical space
between them that may or may not be filled with a solid
material.
[0197] Backside metallization may be achieved by sputtering, vapor
depositing, laser depositing, bombarding, condensing, or physically
attaching the metalizing material thereto.
[0198] Additional examples of capsule designs are now described
with reference to FIGS. 37-45.
[0199] If desired, the tag 15 may be built into the capsule 17,
which may