U.S. patent application number 12/537245 was filed with the patent office on 2009-11-26 for sensor inserter assembly.
This patent application is currently assigned to Abbott Diabetes Care Inc.. Invention is credited to Stephen J. Flynn, Jeffery V. Funderburk, Bradley D. Kelemen, Brian VanHiel, Duane O. Yamasaki.
Application Number | 20090292184 12/537245 |
Document ID | / |
Family ID | 32685148 |
Filed Date | 2009-11-26 |
United States Patent
Application |
20090292184 |
Kind Code |
A1 |
Funderburk; Jeffery V. ; et
al. |
November 26, 2009 |
Sensor Inserter Assembly
Abstract
An analyte monitor includes a sensor, a sensor control unit, and
a display unit. The sensor control unit typically has a housing
adapted for placement on skin and is adapted to receive a portion
of an electrochemical sensor. The sensor control unit also includes
two or more conductive contacts disposed on the housing and
configured for coupling to two or more contact pads on the sensor.
A transmitter is disposed in the housing and coupled to the
plurality of conductive contacts for transmitting data obtained
using the sensor. The display unit has a receiver for receiving
data transmitted by the transmitter of the sensor control unit and
a display coupled to the receiver for displaying an indication of a
level of an analyte, such as blood glucose. An inserter having a
retractable introducer is provided for subcutaneously implanting
the sensor in a predictable and reliable fashion.
Inventors: |
Funderburk; Jeffery V.;
(Fremont, CA) ; Yamasaki; Duane O.; (El Cerrito,
CA) ; VanHiel; Brian; (Marietta, GA) ; Flynn;
Stephen J.; (Peachtree City, GA) ; Kelemen; Bradley
D.; (Longmont, CO) |
Correspondence
Address: |
JACKSON & CO., LLP
6114 LA SALLE AVENUE, #507
OAKLAND
CA
94611-2802
US
|
Assignee: |
Abbott Diabetes Care Inc.
Alameda
CA
|
Family ID: |
32685148 |
Appl. No.: |
12/537245 |
Filed: |
August 6, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11899917 |
Sep 6, 2007 |
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12537245 |
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10703214 |
Nov 5, 2003 |
7381184 |
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11899917 |
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60424099 |
Nov 5, 2002 |
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Current U.S.
Class: |
600/309 |
Current CPC
Class: |
G16H 50/30 20180101;
A61M 2230/201 20130101; A61B 5/1473 20130101; A61B 5/6849 20130101;
G16H 10/60 20180101; A61B 5/1451 20130101; A61B 5/14542 20130101;
A61M 2205/3507 20130101; A61B 5/6833 20130101; A61N 1/05 20130101;
G16H 10/40 20180101; A61B 5/14532 20130101; A61B 17/3468 20130101;
A61B 2560/045 20130101; A61B 5/14546 20130101; G16H 50/00 20180101;
A61B 5/14503 20130101 |
Class at
Publication: |
600/309 |
International
Class: |
A61B 5/145 20060101
A61B005/145 |
Claims
1. (canceled)
2. A method for inserting a transcutaneous analyte sensor into a
host using an applicator, the method comprising the steps of:
pushing on a first component of an applicator for inserting a
transcutaneous analyte sensor into a host, so as to insert an
introducer and the sensor into the skin of the host; and pulling on
a second component of the applicator so as to retract the
introducer from the skin of the host, while leaving the sensor in
the host; wherein the first component and the second component of
the applicator are configured to interact so as to enable insertion
of the sensor and retraction of the introducer using a motion
provided by a user.
3. The method of claim 2 wherein the motion provided the user
includes a continuous motion.
4. The method of claim 2 wherein the motion provided the user
includes a single motion.
5. The method of claim 2 wherein the motion provided the user
includes a single continuous motion.
6. The method of claim 2, wherein the pushing step comprises
pushing on a plunger.
7. The method of claim 2, wherein the pulling step comprises
pulling on a body portion of the second component of the
applicator.
8. The method of claim 2, wherein the applicator is configured to
insert the sensor and retract the introducer by a force provided by
a user's hand.
9. The method of claim 2 wherein the applicator is configured to
insert the sensor and retract the introducer solely by a force
provided by a user's hand.
10. The method of claim 2, wherein the applicator is configured to
insert the sensor and retract the introducer responsive to a
squeezing motion between a user's thumb and fingers.
11. The method of claim 2, wherein the applicator is configured to
sequentially insert the sensor and retract the introducer
responsive to a squeezing motion between a user's thumb and
fingers.
12. The method of claim 2, wherein the applicator is configured to
sequentially insert the sensor and retract the introducer
responsive to a downward force provided by the user.
13. The method of claim 2, wherein the applicator is configured to
sequentially insert the sensor and retract the introducer
responsive to a continuous downward force provided by the user.
14. The method of claim 2, wherein the user is the host.
15. A method for inserting a transcutaneous analyte sensor into a
host using an applicator, the method comprising the steps of:
placing an applicator system against a skin of a host, the
applicator system comprising a housing configured for placement
against the skin of the host, a sensor configured for
transcutaneous placement through the skin of a host, and an
applicator configured for inserting the sensor through the housing
and into the skin of the host; and inserting the sensor into the
host.
16. The method of claim 15 wherein inserting the sensor into the
host includes inserting the sensor into the host by applying a
force to a component of the applicator.
17. A method of using an electrochemical sensor, the method
comprising: adhering a mounting unit to a skin of a patient,
wherein the mounting unit comprises an applicator coupled thereto,
the applicator having an electrochemical sensor disposed therein;
inserting an electrochemical sensor into the skin of the patient
using the applicator; releasing the applicator; and coupling an
electronics unit body to the mounting unit, whereby the mounting
unit is coupled with a plurality of conductive contacts disposed on
the electronics unit body.
18. The method of claim 17 wherein a contact disposed on the
mounting unit is coupled with the plurality of conductive contacts
disposed on the electronics unit body.
19. The method of claim 18 wherein the contact includes a plurality
of conductive contacts.
20. A method, comprising the step of: retaining an analyte sensor
within an introducer during the sensor insertion into a patient
such that the sensor is positioned at a relatively fixed position
with respect to the introducer.
21. The method of claim 20, further including the step of:
positioning the sensor to be in fluid contact with a biological
fluid of a patient.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This non-provisional application is related to and claims
priority based on U.S. Provisional Application No. 60/424,099,
entitled "Sensor Inserter Device and Methods of Use," filed on Nov.
5, 2002, which is incorporated herein in its entirety by this
reference.
FIELD OF THE INVENTION
[0002] The present invention is, in general, directed to devices
and methods for the in vivo monitoring of an analyte, such as
glucose or lactate, using a sensor to provide information to a
patient about the level of the analyte. More particularly, the
present invention relates to devices and methods for inserting a
subcutaneously implantable electrochemical sensor in a patient for
such monitoring.
BACKGROUND OF THE INVENTION
[0003] The monitoring of the level of glucose or other analytes,
such as lactate or oxygen, in certain individuals is vitally
important to their health. High or low levels of glucose or other
analytes may have detrimental effects. The monitoring of glucose is
particularly important to individuals with diabetes, as they must
determine when insulin is needed to reduce glucose levels in their
bodies or when additional glucose is needed to raise the level of
glucose in their bodies.
[0004] A conventional technique used by many diabetics for
personally monitoring their blood glucose level includes the
periodic drawing of blood, the application of that blood to a test
strip, and the determination of the blood glucose level using
colorimetric, electrochemical, or photometric detection. This
technique does not permit continuous or automatic monitoring of
glucose levels in the body, but typically must be performed
manually on a periodic basis. Unfortunately, the consistency with
which the level of glucose is checked varies widely among
individuals. Many diabetics find the periodic testing inconvenient
and they sometimes forget to test their glucose level or do not
have time for a proper test. In addition, some individuals wish to
avoid the pain associated with the test. These situations may
result in hyperglycemic or hypoglycemic episodes. An in vivo
glucose sensor that continuously or automatically monitors the
individual's glucose level would enable individuals to more easily
monitor their glucose, or other analyte, levels.
[0005] A variety of devices have been developed for continuous or
automatic monitoring of analytes, such as glucose, in the blood
stream or interstitial fluid. A number of these devices use
electrochemical sensors which are directly implanted into a blood
vessel or in the subcutaneous tissue of a patient. However, these
devices are often difficult to reproducibly and inexpensively
manufacture in large numbers. In addition, these devices are
typically large, bulky, and/or inflexible, and many can not be used
effectively outside of a controlled medical facility, such as a
hospital or a doctor's office, unless the patient is restricted in
his activities.
[0006] Some devices include a sensor guide which rests on or near
the skin of the patient and may be attached to the patient to hold
the sensor in place. These sensor guides are typically bulky and do
not allow for freedom of movement. In addition, the sensor guides
or the sensors include cables or wires for connecting the sensor to
other equipment to direct the signals from the sensors to an
analyzer. The size of the sensor guides and presence of cables and
wires hinders the convenient use of these devices for everyday
applications. The patient's comfort and the range of activities
that can be performed while the sensor is implanted are important
considerations in designing extended-use sensors for continuous or
automatic in vivo monitoring of the level of an analyte, such as
glucose. There is a need for a small, comfortable device which can
continuously monitor the level of an analyte, such as glucose,
while still permitting the patient to engage in normal activities.
Continuous and/or automatic monitoring of the analyte can provide a
warning to the patient when the level of the analyte is at or near
a threshold level. For example, if glucose is the analyte, then the
monitoring device might be configured to warn the patient of
current or impending hyperglycemia or hypoglycemia. The patient can
then take appropriate actions.
SUMMARY OF THE INVENTION
[0007] Generally, the present invention relates to methods and
devices for the continuous and/or automatic in vivo monitoring of
the level of an analyte using a subcutaneously implantable sensor.
Many of these devices are small and comfortable when used, thereby
allowing a wide range of activities. One embodiment includes a
sensor control unit having a housing adapted for placement on skin.
The housing is also adapted to receive a portion of an
electrochemical sensor. The sensor control unit includes two or
more conductive contacts disposed on the housing and configured for
coupling to two or more contact pads on the sensor. A transmitter
is disposed in the housing and coupled to the plurality of
conductive contacts for transmitting data obtained using the
sensor. The sensor control unit may also include a variety of
optional components, such as, for example, adhesive for adhering to
the skin, a mounting unit, a receiver, a processing circuit, a
power supply (e.g., a battery), an alarm system, a data storage
unit, a watchdog circuit, and a measurement circuit. The sensor
itself has at least one working electrode and at least one contact
pad coupled to the working electrode or electrodes. The sensor may
also include optional components, such as, for example, a counter
electrode, a counter/reference electrode, a reference electrode,
and a temperature probe. The analyte monitoring system also
includes a display unit that has a receiver for receiving data from
the sensor control unit and a display coupled to the receiver for
displaying an indication of the level of an analyte. The display
unit may optionally include a variety of components, such as, for
example, a transmitter, an analyzer, a data storage unit, a
watchdog circuit, an input device, a power supply, a clock, a lamp,
a pager, a telephone interface, a computer interface, an alarm or
alarm system, a radio, and a calibration unit. In addition, the
analyte monitoring system or a component of the analyte monitoring
system may optionally include a processor capable of determining a
drug or treatment protocol and/or a drug delivery system.
[0008] According to one aspect of the invention, an insertion kit
is disclosed for inserting an electrochemical sensor into a
patient. The insertion kit includes an introducer. A portion of the
introducer has a sharp, rigid, planer structure adapted to support
the sensor during insertion of the electrochemical sensor. The
insertion kit also includes an insertion gun having a port
configured to accept the electrochemical sensor and the introducer.
The insertion gun has a driving mechanism for driving the
introducer and electrochemical sensor into the patient, and a
retraction mechanism for removing the introducer while leaving the
sensor within the patient.
[0009] According to another aspect of the invention, a method of
using an electrochemical sensor is disclosed. A mounting unit is
adhered to skin of a patient. An insertion gun is aligned with a
port on the mounting unit. The electrochemical sensor is disposed
within the insertion gun and then the electrochemical sensor is
inserted into the skin of the patient using the insertion gun. The
insertion gun is removed and a housing of the sensor control unit
is mounted on the mounting base. A plurality of conductive contacts
disposed on the housing is coupled to a plurality of contact pads
disposed on the electrochemical sensor to prepare the sensor for
use.
[0010] The above summary of the present invention is not intended
to describe each disclosed embodiment or every implementation of
the present invention. The Figures and the detailed description
which follow more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention may be more completely understood in
consideration of the following detailed description of various
embodiments of the invention in connection with the accompanying
drawings, in which:
[0012] FIG. 1 is a block diagram of one embodiment of a
subcutaneous analyte monitor using a subcutaneously implantable
analyte sensor, according to the invention.
[0013] FIG. 2 is a top view of one embodiment of an analyte sensor,
according to the invention.
[0014] FIG. 3 is an expanded side view of one embodiment of a
sensor and an introducer, according to the invention.
[0015] FIGS. 4A, 4B, 4C are cross-sectional views of three
embodiments of the introducer of FIG. 3.
[0016] FIG. 5 is a cross-sectional view of one embodiment of a
on-skin sensor control unit, according to the invention.
[0017] FIG. 6 is a top view of a base of the on-skin sensor control
unit of FIG. 5.
[0018] FIG. 7 is a bottom view of a cover of the on-skin sensor
control unit of FIG. 5.
[0019] FIG. 8 is a perspective view of the on-skin sensor control
unit of FIG. 5 on the skin of a patient.
[0020] FIG. 9 is a perspective view of the internal structure of an
insertion gun, according to the invention.
[0021] FIG. 10A is a top view of one embodiment of an on-skin
sensor control unit, according to the invention.
[0022] FIG. 10B is a top view of one embodiment of a mounting unit
of the on-skin sensor control unit of FIG. 10A.
[0023] FIG. 11A is a top view of another embodiment of an on-skin
sensor control unit after insertion of an introducer and a sensor,
according to the invention.
[0024] FIG. 11B is a top view of one embodiment of a mounting unit
of the on-skin sensor control unit of FIG. 11A.
[0025] FIG. 11C is a top view of one embodiment of a housing for at
least a portion of the electronics of the on-skin sensor control
unit of FIG. 11A.
[0026] FIG. 11D is a bottom view of the housing of FIG. 11C.
[0027] FIG. 11E is a top view of the on-skin sensor control unit of
FIG. 11A with a cover of the housing removed.
[0028] FIG. 12 depicts an introducer, sensor, insertion gun and
mounting unit, which can be assembled and sold together in an
insertion kit.
[0029] FIG. 13 is a perspective view showing a preferred commercial
embodiment of a sensor inserter and adhesive mount constructed
according to the invention.
[0030] FIG. 14 is a perspective view of the adhesive mount and
sensor attached to the patient's skin.
[0031] FIG. 15 is a perspective view of the transmitter attached to
the adhesive mount.
[0032] FIG. 16 is an exploded perspective view of the preferred
commercial embodiment of FIG. 13.
[0033] FIG. 17 is a side elevation view of the preferred commercial
embodiment of FIG. 13.
[0034] FIG. 18 is an end elevation view of the preferred commercial
embodiment of FIG. 13.
[0035] FIG. 19 is a cross-sectional view taken along line 19-19 in
FIG. 18.
[0036] FIG. 20 is a cross-sectional view taken along line 20-20 in
FIG. 17.
[0037] FIG. 21 is a broken away view similar to FIG. 20, showing
the shuttle in the neutral position.
[0038] FIG. 22 is a broken away view similar to FIG. 20, showing
the shuttle in the cocked position.
[0039] FIG. 23 is a broken away view similar to FIG. 20, showing
the shuttle in the insertion position.
[0040] FIG. 24 is a cross-sectional view taken along line 24-24 in
FIG. 17.
[0041] FIG. 25 is a perspective view of a transcutaneously
implantable sensor.
[0042] FIG. 26A is a perspective view of a sensor introducer.
[0043] FIG. 26B is a bottom view of the introducer shown in FIG.
26A.
[0044] FIG. 27 is a perspective view of a shuttle member.
[0045] FIG. 28 is a top plan view of an oversized adhesive
tape.
[0046] FIG. 29 is a perspective view of the transmitter attached to
the adhesive mount and showing the sensor sandwiched
therebetween.
[0047] FIG. 30 is a perspective view of the interconnect on one end
of the transmitter.
[0048] FIG. 31 is an enlarged perspective view of the interconnect
of FIG. 30 with the seal and one spring removed for clarity.
[0049] FIG. 32 is an enlarged perspective view of the interconnect
seal.
[0050] FIG. 33A is a perspective view of an alternative embodiment
of a sensor inserter kit.
[0051] FIG. 33B is an exploded view of some of the components shown
assembled in FIG. 33A.
[0052] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0053] The present invention is applicable to an analyte monitoring
system using an implantable sensor for the in vivo determination of
a concentration of an analyte, such as glucose or lactate, in a
fluid. The sensor can be, for example, subcutaneously implanted in
a patient for the continuous or periodic monitoring an analyte in a
patient's interstitial fluid. This can then be used to infer the
glucose level in the patient's bloodstream. Other in vivo analyte
sensors can be made, according to the invention, for insertion into
a vein, artery, or other portion of the body containing fluid. The
analyte monitoring system is typically configured for monitoring
the level of the analyte over a time period which may range from
days to weeks or longer.
[0054] The analyte monitoring systems of the present invention can
be utilized under a variety of conditions. The particular
configuration of a sensor and other units used in the analyte
monitoring system may depend on the use for which the analyte
monitoring system is intended and the conditions under which the
analyte monitoring system will operate. One embodiment of the
analyte monitoring system includes a sensor configured for
implantation into a patient or user. For example, implantation of
the sensor may be made in the arterial or venous systems for direct
testing of analyte levels in blood. Alternatively, a sensor may be
implanted in the interstitial tissue for determining the analyte
level in interstitial fluid. This level may be correlated and/or
converted to analyte levels in blood or other fluids. The site and
depth of implantation may affect the particular shape, components,
and configuration of the sensor. Subcutaneous implantation may be
preferred, in some cases, to limit the depth of implantation of the
sensor. Sensors may also be implanted in other regions of the body
to determine analyte levels in other fluids. Examples of suitable
sensor for use in the analyte monitoring systems of the invention
are described in U.S. patent application Ser. No. 09/034,372 and
Ser. No. 09/753,746 (the complete parent application to this CIP),
both incorporated herein by reference.
[0055] One embodiment of the analyte monitoring system 40 for use
with an implantable sensor 42, and particularly for use with a
subcutaneously implantable sensor, is illustrated in block diagram
form in FIG. 1. The analyte monitoring system 40 includes, at
minimum, a sensor 42, a portion of which is configured for
implantation (e.g., subcutaneous, venous, or arterial implantation)
into a patient, and a sensor control unit 44. The sensor 42 is
coupled to the sensor control unit 44 which is typically attached
to the skin of a patient. The sensor control unit 44 operates the
sensor 42, including, for example, providing a voltage across the
electrodes of the sensor 42 and collecting signals from the sensor
42. The sensor control unit 44 may evaluate the signals from the
sensor 42 and/or transmit the signals to one or more optional
receiver/display units 46, 48 for evaluation. The sensor control
unit 44 and/or the receiver/display units 46, 48 may display or
otherwise communicate the current level of the analyte.
Furthermore, the sensor control unit 44 and/or the receiver/display
units 46, 48 may indicate to the patient, via, for example, an
audible, visual, or other sensory-stimulating alarm, when the level
of the analyte is at or near a threshold level. In some
embodiments, a electrical shock can be delivered to the patient as
a warning through one of the electrodes or the optional temperature
probe of the sensor. For example, if glucose is monitored then an
alarm may be used to alert the patient to a hypoglycemic or
hyperglycemic glucose level and/or to impending hypoglycemia or
hyperglycemia.
[0056] A sensor 42 includes at least one working electrode 58
formed on a substrate 50, as shown in FIG. 2. The sensor 42 may
also include at least one counter electrode 60 (or
counter/reference electrode) and/or at least one reference
electrode 62. The substrate 50 of the sensor may be formed using a
variety of non-conducting materials, including, for example,
polymeric or plastic materials and ceramic materials. Suitable
materials for a particular sensor 42 may be determined, at least in
part, based on the desired use of the sensor 42 and properties of
the materials.
[0057] In some embodiments, the substrate is flexible. For example,
if the sensor 42 is configured for implantation into a patient,
then the sensor 42 may be made flexible (although rigid sensors may
also be used for implantable sensors) to reduce pain to the patient
and damage to the tissue caused by the implantation of and/or the
wearing of the sensor 42. A flexible substrate 50 often increases
the patient's comfort and allows a wider range of activities.
Suitable materials for a flexible substrate 50 include, for
example, non-conducting plastic or polymeric materials and other
non-conducting, flexible, deformable materials. Examples of useful
plastic or polymeric materials include thermoplastics such as
polycarbonates, polyesters (e.g., Mylar.TM. and polyethylene
terephthalate (PET)), polyvinyl chloride (PVC), polyurethanes,
polyethers, polyamides, polyimides, or copolymers of these
thermoplastics, such as PETG (glycol-modified polyethylene
terephthalate).
[0058] In other embodiments, the sensors 42 are made using a
relatively rigid substrate 50 to, for example, provide structural
support against bending or breaking. Examples of rigid materials
that may be used as the substrate 50 include poorly conducting
ceramics, such as aluminum oxide and silicon dioxide. One advantage
of an implantable sensor 42 having a rigid substrate is that the
sensor 42 may have a sharp point and/or a sharp edge to aid in
implantation of a sensor 42 without an additional introducer.
[0059] It will be appreciated that for many sensors 42 and sensor
applications, both rigid and flexible sensors will operate
adequately. The flexibility of the sensor 42 may also be controlled
and varied along a continuum by changing, for example, the
composition and/or thickness of the substrate 50.
[0060] In addition to considerations regarding flexibility, it is
often desirable that implantable sensors 42 should have a substrate
50 which is non-toxic. Preferably, the substrate 50 is approved by
one or more appropriate governmental agencies or private groups for
in vivo use.
[0061] Although the substrate 50 in at least some embodiments has
uniform dimensions along the entire length of the sensor 42, in
other embodiments, the substrate 50 has a distal end 67 and a
proximal end 65 with different widths 53, 55, respectively, as
illustrated in FIG. 2. In these embodiments, the distal end 67 of
the substrate 50 may have a relatively narrow width 53. For sensors
42 which are implantable into the subcutaneous tissue or another
portion of a patient's body, the narrow width 53 of the distal end
67 of the substrate 50 may facilitate the implantation of the
sensor 42. Often, the narrower the width of the sensor 42, the less
pain the patient will feel during implantation of the sensor and
afterwards. The sensor 42 is designed to be a replaceable component
in an implantable analyte monitor. Typically, the sensor 42 is
capable of operation over a period of days. Preferably, the period
of operation is at least three days. The sensor 42 can then be
removed and replaced with a new sensor.
[0062] An introducer 120 can be used to subcutaneously insert the
sensor 42 into the patient, as illustrated in FIG. 3. The
introducer 120 is typically formed using structurally rigid
materials, such as metal or rigid plastic. Preferred materials
include stainless steel and ABS (acrylonitrile-butadiene-styrene)
plastic. In some embodiments, the introducer 120 is pointed and/or
sharp at the tip 121 to facilitate penetration of the skin of the
patient. A sharp, thin introducer may reduce pain felt by the
patient upon insertion of the sensor 42. In other embodiments, the
tip 121 of the introducer 120 has other shapes, including a blunt
or flat shape. These embodiments may be particularly useful when
the introducer 120 does not penetrate the skin but rather serves as
a structural support for the sensor 42 as the sensor 42 is pushed
into the skin.
[0063] The introducer 120 may have a variety of cross-sectional
shapes, as shown in FIGS. 4A, 4B, and 4C. The introducer 120
illustrated in FIG. 4A is a flat, planar, pointed strip of rigid
material which may be attached or otherwise coupled to the sensor
42 to ease insertion of the sensor 42 into the skin of the patient,
as well as to provide structural support to the sensor 42 during
insertion. The introducers 120 of FIGS. 4B and 4C are U- or
V-shaped implements that support the sensor 42 to limit the amount
that the sensor 42 may bend or bow during insertion. The
cross-sectional width 124 of the introducers 120 illustrated in
FIGS. 4B and 4C is typically 1 mm or less, preferably 700 .mu.m or
less, more preferably 500 .mu.m or less, and most preferably 300
.mu.m or less. The cross-sectional height 126 of the introducer 120
illustrated in FIGS. 4B and 4C is typically about 1 mm or less,
preferably about 700 .mu.M or less, and more preferably about 500
.mu.m or less.
[0064] The sensor 42 itself may include optional features to
facilitate insertion. For example, the sensor 42 may be pointed at
the tip 123 to ease insertion, as illustrated in FIG. 3. In
addition, the sensor 42 may include a barb 125 which helps retain
the sensor 42 in the subcutaneous tissue of the patient. The barb
125 may also assist in anchoring the sensor 42 within the
subcutaneous tissue of the patient during operation of the sensor
42. However, the barb 125 is typically small enough that little
damage is caused to the subcutaneous tissue when the sensor 42 is
removed for replacement. The sensor 42 may also include a notch 127
that can be used in cooperation with a corresponding structure (not
shown) in the introducer to apply pressure against the sensor 42
during insertion, but disengage as the introducer 120 is removed.
One example of such a structure in the insertion device is a rod
(not shown) between two opposing sides of an introducer 120 and at
an appropriate height of the introducer 120.
[0065] In operation, the sensor 42 is placed within or next to the
introducer 120 and then a force is provided against the introducer
120 and/or sensor 42 to carry the sensor 42 into the skin of the
patient. In one embodiment, the force is applied to the sensor 42
to push the sensor into the skin, while the introducer 120 remains
stationary and provides structural support to the sensor 42.
Alternatively, the force is applied to the introducer 120 and
optionally to the sensor 42 to push a portion of both the sensor 42
and the introducer 120 through the ski of the patient and into the
subcutaneous tissue. The introducer 120 is optionally pulled out of
the skin and subcutaneous tissue with the sensor 42 remaining in
the subcutaneous tissue due to frictional forces between the sensor
42 and the patient's tissue. If the sensor 42 includes the optional
barb 125, then this structure may also facilitate the retention of
the sensor 42 within the interstitial tissue as the barb catches in
the tissue.
[0066] The force applied to the introducer 120 and/or the sensor 42
may be applied manually or mechanically. Preferably, the sensor 42
is reproducibly inserted through the skin of the patient. In one
embodiment, an insertion gun is used to insert the sensor. One
example of an insertion gun 200 for inserting a sensor 42 is shown
in FIG. 9. The insertion gun 200 includes a housing 202 and a
carrier 204. The introducer 120 is typically mounted on the carrier
204 and the sensor 42 is pre-loaded into the introducer 120. The
carrier 204 drives the sensor 42 and, optionally, the introducer
120 into the skin of the patient using, for example, a cocked or
wound spring, a burst of compressed gas, an electromagnet repelled
by a second magnet, or the like, within the insertion gun 200. In
some instances, for example, when using a spring, the carrier 204
and introducer 120 may be moved, cocked, or otherwise prepared to
be directed towards the skin of the patient.
[0067] After the sensor 42 is inserted, the insertion gun 200 may
contain a mechanism which pulls the introducer 120 out of the skin
of the patient. Such a mechanism may use a spring, electromagnet,
or the like to remove the introducer 120.
[0068] The insertion gun may be reusable. The introducer 120 is
often disposable to avoid the possibility of contamination.
Alternatively, the introducer 120 may be sterilized and reused. In
addition, the introducer 120 and/or the sensor 42 may be coated
with an anticlotting agent to prevent fouling of the sensor 42.
[0069] In one embodiment, the sensor 42 is injected between 2 to 12
mm into the interstitial tissue of the patient for subcutaneous
implantation. Preferably, the sensor is injected 3 to 9 mm, and
more preferably 5 to 7 mm, into the interstitial tissue. Other
embodiments of the invention, may include sensors implanted in
other portions of the patient, including, for example, in an
artery, vein, or organ. The depth of implantation varies depending
on the desired implantation target.
[0070] Although the sensor 42 may be inserted anywhere in the body,
it is often desirable that the insertion site be positioned so that
the on-skin sensor control unit 44 can be concealed. In addition,
it is often desirable that the insertion site be at a place on the
body with a low density of nerve endings to reduce the pain to the
patient. Examples of preferred sites for insertion of the sensor 42
and positioning of the on-skin sensor control unit 44 include the
abdomen, thigh, leg, upper arm, and shoulder.
[0071] An insertion angle is measured from the plane of the skin
(i.e., inserting the sensor perpendicular to the skin would be a
90.degree. insertion angle). Insertion angles usually range from 10
to 90.degree., typically from 15 to 60.degree., and often from 30
to 45.degree..
On-Skin Sensor Control Unit
[0072] The on-skin sensor control unit 44 is configured to be
placed on the skin of a patient. The on-skin sensor control unit 44
is optionally formed in a shape that is comfortable to the patient
and which may permit concealment, for example, under a patient's
clothing. The thigh, leg, upper arm, shoulder, or abdomen are
convenient parts of the patient's body for placement of the on-skin
sensor control unit 44 to maintain concealment. However, the
on-skin sensor control unit 44 may be positioned on other portions
of the patient's body. One embodiment of the on-skin sensor control
unit 44 has a thin, oval shape to enhance concealment, as
illustrated in FIGS. 5-7. However, other shapes and sizes may be
used.
[0073] The particular profile, as well as the height, width,
length, weight, and volume of the on-skin sensor control unit 44
may vary and depends, at least in part, on the components and
associated functions included in the on-skin sensor control unit
44, as discussed below. For example, in some embodiments, the
on-skin sensor control unit 44 has a height of 1.3 cm or less, and
preferably 0.7 cm or less. In some embodiments, the on-skin sensor
control unit 44 has a weight of 90 grams or less, preferably 45
grams or less, and more preferably 25 grams or less. In some
embodiments, the on-skin sensor control unit 44 has a volume of
about 15 cm.sup.3 or less, preferably about 10 cm.sup.3 or less,
more preferably about 5 cm.sup.3 or less, and most preferably about
2.5 cm.sup.3 or less.
[0074] The on-skin sensor control unit 44 includes a housing 45, as
illustrated in FIGS. 5-7. The housing 45 is typically formed as a
single integral unit that rests on the skin of the patient. The
housing 45 typically contains most or all of the electronic
components, described below, of the on-skin sensor control unit 44.
The on-skin sensor control unit 44 usually includes no additional
cables or wires to other electronic components or other devices. If
the housing includes two or more parts, then those parts typically
fit together to form a single integral unit.
[0075] In some embodiments, conductive contacts 80 are provided on
the exterior of the housing 45. In other embodiments, the
conductive contacts 80 are provided on the interior of the housing
45, for example, within a hollow or recessed region.
[0076] In some embodiments, the housing 45 of the on-skin sensor
control unit 44 is a single piece. The conductive contacts 80 may
be formed on the exterior of the housing 45 or on the interior of
the housing 45 provided there is a port 78 in the housing 45
through which the sensor 42 can be directed to access the
conductive contacts 80.
[0077] In other embodiments, the housing 45 of the on-skin sensor
control unit 44 is formed in at least two separate portions that
fit together to form the housing 45, for example, a base 74 and a
cover 76, as illustrated in FIGS. 5-7. The two or more portions of
the housing 45 may be entirely separate from each other.
Alternatively, at least some of the two or more portions of the
housing 45 may be connected together, for example, by a hinge, to
facilitate the coupling of the portions to form the housing 45 of
the on-skin sensor control unit 44.
[0078] These two or more separate portions of the housing 45 of the
on-skin sensor control unit 44 may have complementary, interlocking
structures, such as, for example, interlocking ridges or a ridge on
one component and a complementary groove on another component, so
that the two or more separate components may be easily and/or
firmly coupled together. This may be useful, particularly if the
components are taken apart and fit together occasionally, for
example, when a battery or sensor 42 is replaced. However, other
fasteners may also be used to couple the two or more components
together, including, for example, screws, nuts and bolts, nails,
staples, rivets, or the like. In addition, adhesives, both
permanent or temporary, may be used including, for example, contact
adhesives, pressure sensitive adhesives, glues, epoxies, adhesive
resins, and the like.
[0079] Typically, the housing 45 is at least water resistant to
prevent the flow of fluids into contact with the components in the
housing, including, for example, the conductive contacts 80.
Preferably, the housing is waterproof. In one embodiment, two or
more components of the housing 45, for example, the base 74 and the
cover 76, fit together tightly to form a hermetic, waterproof, or
water resistant seal so that fluids can not flow into the interior
of the on-skin sensor control unit 44. This may be useful to avoid
corrosion currents and/or degradation of items within the on-skin
sensor control unit 44, such as the conductive contacts, the
battery, or the electronic components, particularly when the
patient engages in such activities as showering, bathing, or
swimming.
[0080] Water resistant, as used herein, means that there is no
penetration of water through a water resistant seal or housing when
immersed in water at a depth of one meter at sea level. Waterproof,
as used herein, means that there is no penetration of water through
the waterproof seal or housing when immersed in water at a depth of
ten meters, and preferably fifty meters, at sea level. It is often
desirable that the electronic circuitry, power supply (e.g.,
battery), and conductive contacts of the on-skin sensor control
unit, as well as the contact pads of the sensor, are contained in a
water resistant, and preferably, a waterproof, environment.
[0081] The on-skin sensor control unit 44 is typically attached to
the skin 75 of the patient, as illustrated in FIG. 8. The on-skin
sensor control unit 44 may be attached by a variety of techniques
including, for example, by adhering the on-skin sensor control unit
44 directly to the skin 75 of the patient with an adhesive provided
on at least a portion of the housing 45 of the on-skin sensor
control unit 44 which contacts the skin 75, by suturing the on-skin
sensor control unit 44 to the skin 75 through suture openings (not
shown) in the sensor control unit 44, or by strapping the on-skin
sensor control unit 44 to the skin 75.
[0082] Another method of attaching the housing 45 of the on-skin
sensor control unit 44 to the skin 75 includes using a mounting
unit, 77. The mounting unit 77 is often a part of the on-skin
sensor control unit 44. One example of a suitable mounting unit 77
is a double-sided adhesive strip, one side of which is adhered to a
surface of the skin of the patient and the other side is adhered to
the on-skin sensor control unit 44. In this embodiment, the
mounting unit 77 may have an optional opening 79 which is large
enough to allow insertion of the sensor 42 through the opening 79.
Alternatively, the sensor may be inserted through a thin adhesive
and into the skin.
[0083] A variety of adhesives may be used to adhere the on-skin
sensor control unit 44 to the skin 75 of the patient, either
directly or using the mounting unit 77, including, for example,
pressure sensitive adhesives (PSA) or contact adhesives.
Preferably, an adhesive is chosen which is not irritating to all or
a majority of patients for at least the period of time that a
particular sensor 42 is implanted in the patient. Alternatively, a
second adhesive or other skin-protecting compound may be included
with the mounting unit so that a patient, whose skin is irritated
by the adhesive on the mounting unit 77, can cover his skin with
the second adhesive or other skin-protecting compound and then
place the mounting unit 77 over the second adhesive or other
skin-protecting compound. This should substantially prevent the
irritation of the skin of the patient because the adhesive on the
mounting unit 77 is no longer in contact with the skin, but is
instead in contact with the second adhesive or other
skin-protecting compound.
[0084] Returning to FIG. 8, when the sensor 42 is changed, the
on-skin sensor control unit 44 may be moved to a different position
on the skin 75 of the patient, for example, to avoid excessive
irritation. Alternatively, the on-skin sensor control unit 44 may
remain at the same place on the skin of the patient until it is
determined that the unit 44 should be moved.
[0085] Another embodiment of a mounting unit 77 used in an on-skin
sensor control unit 44 is illustrated in FIGS. 10A and 10B. The
mounting unit 77 and a housing 45 of an on-skin sensor control unit
44 are mounted together in, for example, an interlocking manner, as
shown in FIG. 10A. The mounting unit 77 is formed, for example,
using plastic or polymer materials, including, for example,
polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS
polymers, and copolymers thereof. The mounting unit 77 may be
formed using a variety of techniques including, for example,
injection molding, compression molding, casting, and other molding
methods.
[0086] The mounting unit 77 typically includes an adhesive on a
bottom surface of the mounting unit 77 to adhere to the skin of the
patient or the mounting unit 77 is used in conjunction with, for
example, double-sided adhesive tape or the like. The mounting unit
77 typically includes an opening 79 through which the sensor 42 is
inserted, as shown in FIG. 10B. The mounting unit 77 may also
include a support structure 220 for holding the sensor 42 in place
and against the conductive contacts 80 on the on-skin sensor
control unit 42. The mounting unit 77, also, optionally, includes a
positioning structure 222, such as an extension of material from
the mounting unit 77, that corresponds to a structure (not shown),
such as an opening, on the sensor 42 to facilitate proper
positioning of the sensor 42, for example, by aligning the two
complementary structures.
[0087] In another embodiment, a coupled mounting unit 77 and
housing 45 of an on-skin sensor control unit 44 is provided on an
adhesive patch 204 with an optional cover 206 to protect and/or
confine the housing 45 of the on-skin sensor control unit 44, as
illustrated in FIG. 11A. The optional cover may contain an adhesive
or other mechanism for attachment to the housing 45 and/or mounting
unit 77. The mounting unit 77 typically includes an opening 49
through which a sensor 42 is disposed, as shown in FIG. 11B. The
opening 49 may optionally be configured to allow insertion of the
sensor 42 through the opening 49 using an introducer 120 or
insertion gun 200 (see FIG. 9). The housing 45 of the on-skin
sensor control unit 44 has a base 74 and a cover 76, as illustrated
in FIG. 11C. A bottom view of the housing 45, as shown in FIG. 11D,
illustrates ports 230 through which conductive contacts (not shown)
extend to connect with contact pads on the sensor 42. A board 232
for attachment of circuit components may optionally be provided
within the on-skin sensor control unit 44, as illustrated in FIG.
11E.
[0088] In some embodiments, the adhesive on the on-skin sensor
control unit 44 and/or on any of the embodiments of the mounting
unit 77 is water resistant or waterproof to permit activities such
as showering and/or bathing while maintaining adherence of the
on-skin sensor control unit 44 to the skin 75 of the patient and,
at least in some embodiments, preventing water from penetrating
into the sensor control unit 44. The use of a water resistant or
waterproof adhesive combined with a water resistant or waterproof
housing 45 protects the components in the sensor control unit 44
and the contact between the conductive contacts 80 and the sensor
42 from damage or corrosion. An example of a non-irritating
adhesive that repels water is Tegaderm (3M, St. Paul, Minn.).
[0089] In one embodiment, the on-skin sensor control unit 44
includes a sensor port 78 through which the sensor 42 enters the
subcutaneous tissue of the patient, as shown in FIGS. 5 to 7. The
sensor 42 may be inserted into the subcutaneous tissue of the
patient through the sensor port 78. The on-skin sensor control unit
44 may then be placed on the skin of the patient with the sensor 42
being threaded through the sensor port 78. If the housing 45 of the
sensor 42 has, for example, a base 74 and a cover 76, then the
cover 76 may be removed to allow the patient to guide the sensor 42
into the proper position for contact with the conductive contacts
80.
[0090] Alternatively, if the conductive contacts 80 are within the
housing 45 the patient may slide the sensor 42 into the housing 45
until contact is made between the contact pads 49 and the
conductive contacts 80. The sensor control unit 44 may have a
structure which obstructs the sliding of the sensor 42 further into
the housing once the sensor 42 is properly positioned with the
contact pads 49 in contact with the conductive contacts 80.
[0091] In other embodiments, the conductive contacts 80 are on the
exterior of the housing 45 (see e.g., FIGS. 10A-10B and 11A-11E).
In these embodiments, the patient guides the contacts pads 49 of
the sensor 42 into contact with the conductive contacts 80. In some
cases, a guiding structure may be provided on the housing 45 which
guides the sensor 42 into the proper position. An example of such a
structure includes a set of guiding rails extending from the
housing 45 and having the shape of the sensor 42.
[0092] In some embodiments, when the sensor 42 is inserted using an
introducer 120 (see FIG. 3), the tip of the introducer 120 or
optional insertion gun 200 (see FIG. 9) is positioned against the
skin or the mounting unit 77 at the desired insertion point. In
some embodiments, the introducer 120 is positioned on the skin
without any guide. In other embodiments, the introducer 120 or
insertion gun 200 is positioned using guides (not shown) in the
mounting unit 77 or other portion of the on-skin sensor control
unit 44. In some embodiments, the guides, opening 79 in the
mounting unit 77 and/or sensor port 78 in the housing 45 of the
on-skin sensor control unit 44 have a shape which is complementary
to the shape of the tip of the introducer 120 and/or insertion gun
200 to limit the orientation of the introducer 120 and/or insertion
gun 200 relative to the opening 79 and/or sensor port 78. The
sensor can then be subcutaneously inserted into the patient by
matching the complementary shape of the opening 79 or sensor port
78 with the introducer 120 and/or insertion gun 200.
[0093] In some embodiments, the shapes of a) the guides, opening
79, or sensor port 78, and (b) the introducer 120 or insertion gun
200 are configured such that the two shapes can only be matched in
a single orientation. This aids in inserting the sensor 42 in the
same orientation each time a new sensor is inserted into the
patient. This uniformity in insertion orientation may be required
in some embodiments to ensure that the contact pads 49 on the
sensor 42 are correctly aligned with appropriate conductive
contacts 80 on the on-skin sensor control unit 44. In addition, the
use of the insertion gun, as described above, may ensure that the
sensor 42 is inserted at a uniform, reproducible depth.
[0094] An exemplary on-skin sensor control unit 44 can be prepared
and used in the following manner. A mounting unit 77 having
adhesive on the bottom is applied to the skin. An insertion gun 200
(see FIG. 9) carrying the sensor 42 and the introducer 120 is
positioned against the mounting unit 77. The insertion gun 200 and
mounting unit 77 are optionally designed such that there is only
one position in which the two properly mate. The insertion gun 200
is activated and a portion of the sensor 42 and optionally a
portion of the introducer 120 are driven through the skin into, for
example, the subcutaneous tissue. The insertion gun 200 withdraws
the introducer 120, leaving the portion of the sensor 42 inserted
through the skin. The housing 45 of the on-skin control unit 44 is
then coupled to the mounting unit 77. Optionally, the housing 45
and the mounting unit 77 are formed such that there is only one
position in which the two properly mate. The mating of the housing
45 and the mounting unit 77 establishes contact between the contact
pads 49 (see e.g., FIG. 2) on the sensor 42 and the conductive
contacts 80 on the on-skin sensor control unit 44. Optionally, this
action activates the on-skin sensor control unit 44 to begin
operation.
[0095] The introducer, sensor, insertion gun and mounting unit can
be manufactured, marketed, or sold as a unit. For example, FIG. 12
depicts an introducer 270, sensor 272, insertion gun 274 and
mounting unit 276, which can be assembled (as indicated by the
arrows) and sold together in an insertion kit. In such an
embodiment of an insertion kit, the insertion gun 274 can be
packaged in a pre-loaded fashion, with an introducer 270 and sensor
272 mated or otherwise coupled, the mated sensor 272 and introducer
270 loaded upon the carrier 278 of the insertion gun, and with a
mounting unit 276 already mated with the end of the insertion gun
274.
[0096] In one embodiment, the insertion gun 274 is packaged in a
state where it is ready to thrust the sensor 272 (and perhaps
introducer 270) into subcutaneous tissue. For example, the
insertion gun 274 can be packaged in a "cocked" state, such that
the thrusting force used to introduce the sensor 272 into the
subcutaneous tissue is stored in the device as potential energy (in
the case of the embodiment depicted in FIG. 12, the insertion gun
274 would be "cocked" by compressing its spring 280, thus storing
potential energy within the coils of the spring). Preferably, an
insertion gun 274 packaged in such a manner employs a "safety", a
barrier to prevent the release of the stored potential energy. The
barrier is removed in order to permit the potential energy to be
released. Within the context of the embodiment presented in FIG.
12, an example of a safety is a pin (not pictured) that impedes the
spring from expanding, once compressed. Thus, an insertion kit so
embodied can be obtained at a place of purchase, removed from its
package, and used after removal of the safety, without
necessitating additional steps. Alternatively, the insertion gun
274 can be packaged in the above-described pre-loaded
configuration, but without being "cocked". Thus, an insertion kit
with an "uncocked" insertion gun 274 can be obtained at a place of
purchase, removed from its package, cocked, and used. To facilitate
the insertion kit being ready to use with minimal user-exercised
steps, the insertion kit can be sterilized prior to packaging.
Examples of acceptable sterilizing techniques include exposing the
elements of the insertion kit to gamma radiation or an e-beam.
[0097] Referring to FIGS. 13-33, preferred commercial embodiments
of a sensor inserter constructed according to the invention will
now be described. FIG. 13 shows an overall perspective view of a
sensor inserter kit 300 comprising a single-use sensor inserter 310
and a single-use adhesive mount 312 removably attached to the
bottom thereof.
[0098] As an overview of the operation of inserter kit 300, the kit
comes packaged generally as shown in FIG. 13 with a sensor 314
(best seen in FIGS. 16 and 25) preloaded within inserter 310 and
with inserter 310 in a "cocked" state. After preparing an insertion
site on the skin, typically in the abdominal region, the patient
removes upper liner 316 and lower liner 318 from adhesive mount 312
to expose the bottom surface and a portion of the top surface of an
adhesive tape 320 (best seen in FIG. 16) located beneath mount 312.
Mount 312, with inserter 310 attached, is then applied to the
patient's skin at the insertion site. Safety lock tabs 322 are
squeezed together to allow actuator button 324 to be pressed
causing inserter 310 to fire, thereby inserting sensor 314 into the
patient's skin with a predetermined velocity and force. Once sensor
314 has been inserted into the skin, the patient removes inserter
310 from mount 312 by pressing release tabs 326 on opposite sides
of inserter 310 and lifting inserter 310 away from mount 312.
[0099] Referring to FIG. 14, mount 312 is shown adhered to a
patient's skin 328 with sensor 314 already inserted. Once inserter
310 is removed from mount 312, transmitter 330 can be slid into
place. The circuitry of transmitter 330 makes electrical contact
with the contact pads on sensor 314 after transmitter 330 is fully
seated on mount 312. Once initialization and synchronization
procedures are completed, electrochemical measurements from sensor
314 can be sent wirelessly from transmitter 330 to a portable
receiver 332, as shown in FIG. 15. Sensor 314, mount 312 and
transmitter 330 remain in place on the patient for a predetermined
period, currently envisioned to be three days. These components are
then removed so that sensor 314 and mount 312 can be properly
discarded. The entire procedure above can then be repeated with a
new inserter 310, sensor 314 and mount 312, reusing transmitter 330
and receiver 332.
[0100] Referring to FIG. 16, the preferred inserter kit 300 is
assembled as shown from the following components: housing 334,
actuator button 324, drive spring 336, shuttle 338, introducer
sharp 340, sensor 314, retraction spring 342, inserter base 344,
upper liner 316, adhesive mount 312, adhesive tape 320, and lower
liner 318.
[0101] Sensor 314 has a main surface 346 slidably mounted between
U-shaped rails 348 of introducer sharp 340 and releasably retained
there by sensor dimple 350 which engages introducer dimple 352.
Introducer sharp 340 is mounted to face 354 of shuttle 338, such as
with adhesive, heat stake or ultrasonic weld. Sensor 314 also has a
surface 356 that extends orthogonally from main surface 346 and
just beneath a driving surface 358 of shuttle 338 when mounted
thereon (details of these features are better shown in FIGS. 19 and
25-27.)
[0102] Shuttle 338 is slidably and non-rotabably constrained on
base 344 by arcuate guides 360. As best seen in FIGS. 19, 24 and
27, shuttle 338 is generally formed by an outer ring 362 and an
inner cup-shaped post 364 connected by two bridges 366. Bridges 366
slide between the two slots 368 formed between guides 360 and allow
shuttle 338 to travel along guides 360 without rotating. Retraction
spring 342 is captivated at its outer circumference by guides 360,
at its bottom by the floor 370 of base 344, at its top by bridges
366, and at its inner circumference by the outer surface of shuttle
post 364. Drive spring 336 is captivated at its bottom and outer
circumference by the inside surface of shuttle post 364, at its top
by the ceiling 372 inside actuator button 324, and at its inner
circumference by stem 374 depending from ceiling 372. When drive
spring 336 is compressed between actuator button 324 and shuttle
338 it urges shuttle 338 towards base 344. When retraction spring
342 is compressed between shuttle 338 and base 344, it urges
shuttle 338 towards actuator button 324.
[0103] Actuator button 324 is slidably received within housing 334
from below and resides in opening 376 at the top of housing 334
with limited longitudinal movement. Arms 378 on each side of
actuator button 324 travel in channels 380 along the inside walls
of housing 334, as best seen in FIG. 20. Longitudinal movement of
actuator button 324 is limited in one direction by the base 378 of
arms 378 contacting the edge of opening 376 at the top of housing
334, and in the other direction by the distal ends 384 of arms 378
contacting stops 386 in channels 380. Slots 388 are preferably
provided in the top of housing 334 for ease of housing manufacture
and so tools can be inserted to inwardly compress arms 378 beyond
stops 386 to allow actuator button 324 to be removed from housing
334 if needed.
[0104] When sensor 314, introducer 340, shuttle 338, retraction
spring 342, drive spring 336 and actuator button 324 are assembled
between base 344 and housing 334 as shown in FIG. 16 and described
above, housing 334 is snapped into place on base 344. Base 344 is
held onto housing 334 by upper base barbs 390 that engage upper
openings 392 in housing 334, and lower base barbs 394 (best seen in
FIG. 17) that engage lower openings 396 in housing 334. Slots 398
and 400 are provided for ease of manufacture of housing 334, and
base 344 is preferably removable from housing 334 with tools if
needed.
[0105] Referring to FIG. 19, actuator button 324 is preferably
provided with safety lock tabs 322 hingedly formed on opposite
ends. Tabs 322 can be urged from a relaxed outward position to a
flexed inward position. When in the normal outward position,
shoulders 402 on the outer surfaces of tabs 322 engage the rim 404
of opening 376 to prevent the actuator button 324 from being
depressed, thereby avoiding accidental firing of inserter 310. Tabs
322 can be squeezed inward just enough to clear the rim 404 of
opening 376 while pressing the actuator button 324 down to fire the
inserter. Alternatively, tabs 322 can be squeezed further inward so
that barbs 406 on the inside edges can engage catches 408 located
on a center portion of actuator button 324, thereby defeating the
safety lock to allow later firing by simply pressing down on the
actuator button 324. Preferably, upwardly extending grips 410 are
provided on tabs 322 for better visual indication of safety lock
status and actuation control.
[0106] Referring to FIG. 20, shuttle 338 is provided with laterally
extending barbed fingers 412 which travel in channels 380 along the
inside walls of housing 334. When shuttle 338 is inserted up into
housing 334 far enough, barbed fingers 412 momentarily deflect
inward and then snap outward again to catch on stops 386. In this
"cocked" position as shown, drive spring 336 is compressed and
urging shuttle 338 towards base 344, but barbed fingers 412
catching on stops 386 prevent such travel.
[0107] Referring to FIGS. 21-23, the sequence of loading, cocking,
arming, firing, and automatic retraction of inserter 310 will be
described. It is envisioned that in production, inserters 310 will
be fabricated and fully assembled by one vender except for sensor
314, which will be supplied and installed by a second vendor in a
sterile environment. Accordingly, inserter 310 will be manufactured
and shipped to the sensor vendor in a neutral state, as shown in
FIG. 21. A hole 414 provided through the center of actuator button
324 allows the sensor vendor to insert a pin (manually or by
automated machinery, not shown) through hole 414 to drive shuttle
338 towards base 344 in a controlled fashion and hold it there
against the force of retraction spring 342. This will cause
introducer sharp 340 to be extended through base 344 (as shown in
FIG. 23) so that sensor 314 can be loaded into introducer 340. When
the pin is removed, shuttle 338, introducer 340 and sensor 314 will
retract to the neutral position. The sensor vendor can then cock
the loaded inserter 310 before shipment by pushing another pin (not
shown) from the opposite direction through a central hole 416 in
base 344 (with mount 312 removed) until the pin contacts dimple 418
formed in the bottom of shuttle 338. By pushing shuttle 338 towards
actuator button 324 until barbed fingers 412 clear stops 386, the
inserter 310 is cocked (as shown in FIG. 22.)
[0108] Referring to FIG. 22, inserter 310 is preferably received by
the patient in the cocked position as shown. To use inserter 310,
the patient applies mount 312 to the mounting site and disables the
safety mechanism as previously described, and then pushes actuator
button 324 against the force of drive spring 336. As actuator
button 324 travels toward base 344, drive cam surfaces 420 on arms
378 contact ramped surfaces 422 of barbed fingers 412 and urge them
inward. When fingers 412 are driven inward enough to clear stops
386, shuttle 338 is driven by drive spring 336 with a predetermined
speed and force to an insertion position, as shown in FIG. 23.
[0109] Referring to FIG. 23, inserter 310 is shown in the insertion
position with the tail 424 of introducer sharp 340 extending
through base 344 and mount 312 into the skin of the patient. FIG.
23 shows shuttle 338 in a fully extended position with its lower
surface 426 bottomed out on base 344. However, the lower orthogonal
surface 356 of sensor 314 will contact an exposed sensor contact
portion 428 (best seen in FIGS. 14 and 16) on top of adhesive tape
320 supported from below by the patient's skin, and therefore will
typically stop traveling before reaching the fully bottomed out
position shown. Tail 424 of introducer sharp 340 provides rigidity
and a skin piercing edge 430 for allowing the flexible tail 431 of
sensor 314 to be implanted in the patient's skin. After providing
this function, introducer sharp 340 is immediately removed from the
patient and retracted into a safe position inside housing 334 as
retraction spring 342 (which has been compressed by the travel of
the shuttle) pushes shuttle 338 back towards actuator cap. Sensor
314 is pulled from introducer 340 and held in place by the sensor
contact portion 428 on top of adhesive tape 320 adhering to
orthogonal surface 356 of sensor 314. The geometries of sensor
dimple 350 and mating introducer dimple 352 are chosen to create a
separation force between them that is less than the adhesion force
of tape 320 on orthogonal surface 356, but great enough to retain
sensor 314 in introducer 340 during typical shipping and product
handling shock loads. Driving surface 358 beneath shuttle 338
presses down on top of orthogonal surface 356 to ensure good
contact with adhesive tape 320 before shuttle 338 retracts with
introducer 340. As discussed above with previous embodiments,
barb(s) on sensor tail 431 can be employed to further anchor the
sensor in its operating position.
[0110] Referring again to FIG. 21, retraction spring 342 will
return shuttle 338 to the neutral position as shown after firing,
but without sensor 314 which remains inserted in patient's skin
(not still in introducer 340 as shown here.) Drive spring 336 is
preferably designed to be stiffer than retraction spring 342 so
that shuttle 338 oscillations are quickly dampened out, and so
introducer sharp 340 does not return to sensor 314 or the patient
to cause injury. With sensor 314 now inserted in the patient's
skin, inserter 310 can be removed from mount 312 by inwardly
flexing release tabs 326 on opposite sides of inserter 310 to
remove latch hooks 432 from mount channels 434 and then lifting
inserter 310 away from mount 312. Introducer sharp 340 remains
protected inside housing 334 during disposal of inserter 310.
Transmitter 330 can now be slid into place on mount 312 as
previously described.
[0111] Referring to FIG. 28, an alternative embodiment of adhesive
tape 320' is shown. This oversized tape 320' has the advantage of
holding transmitter 330 in place even when fairly large forces are
placed on it. In this embodiment adhesive tape 320' has a
double-sided portion 436 (adhesive on both top and bottom sides)
residing between mount 312 and the patient's skin, and a
single-sided portion 438 outwardly extending from the double-sided
portion 436, preferably in all directions, for adhering just to the
patient's skin. In the previous embodiment, it is difficult to
separate mount 312 from the skin merely with tension forces, but
applying a force to just one side of mount 312 results in a high
peeling force being applied to that edge of the adhesive tape 320
which causes tape 320 to peel off of the skin. In contrast, any
force applied to transmitter 330 in this alternative embodiment
results in a tension force rather than a peeling force being
applied to tape 320', inhibiting inadvertent removal until an edge
of tape 320' is intentionally peeled up. Preferably, single-sided
portion 438 has a width roughly double the width of double-sided
portion 436. In the preferred embodiment, theses widths are 2.14
and 1.14 inches, respectively. Preferably, the length that
single-sided portion 438 extends beyond double-sided portion 436 is
roughly equivalent to the combined height of transmitter 330
attached to mount 312, in this case about 0.5 inches.
[0112] In the preferred embodiment, sensor 314 is made from a 0.005
inch thick Mylar substrate, such as Dupont Melinex ST-505, print
treated both sides, heat stabilized and bi-axially oriented. Main
surface 346 is 0.315 tall by 0.512 wide, and orthogonal surface 356
is 0.374 wide by 0.202 deep. Sensor tail 431 is 0.230 long by 0.023
wide. Semispherical sensor dimple 350 is 0.050 inches wide and
0.026 inches deep. Introducer 340 is made from SUS 301 medical
grade stainless steel, 0.004 inches thick, having a surface
roughness less than or equal to 0.5 micrometers. The height of the
main portion of introducer 340 is 0.614 inches, and the inside
width is 0.513 inches. The overall thickness of rolled rails 348 is
0.026 inches. The length and width of introducer tail 424 are 0.354
and 0.036 inches, respectively. The preferred angle of the sharp
340 is 21 degrees. Preferably, semispherical introducer dimple 352
has a radius of 0.024 inches. In the preferred embodiment, shuttle
338 has an average speed of at least 1 meter/second, and has a
momentum at its end of travel of about 2.65 lb-m/sec.
[0113] Preferably, housing 334, button 324, shuttle 338, base 344
and mount 312 are all injection molded from G.E. Lexan PC. Inside
and outside working surfaces of arms 378 on button 324 are
preferably lubricated with Dow Corning 360 Medical Fluid. Drive
spring 336 has a free length of 1.25 inches, a working length of
1.00 inch, and a rate between 20 and 30 pounds per inch. Retraction
spring 342 has a free length of 1.5 inches, a working length of
0.35 inches, and a rate between 0.15 and 0.35 pounds per inch.
Adhesive tape 320 preferably is medical grade acrylic adhesive on
polyester film (such as Acutek 0396013) with a semi-bleached kraft
liner having silicon release.
[0114] Referring to FIG. 29, an interconnect 440 is shown for
providing waterproof electrical connections between sensor 314 and
transmitter 330. Interconnect 440 includes a seal 442 mounted on an
end of transmitter 330 that contacts one side of sensor 314 when
transmitter 330 is slid onto mount 312. When transmitter 330 is
locked into place on mount 312, seal 442 is compressed between
transmitter 330 and sensor 314 and urges sensor 314 against raised
end stop 444 of mount 312.
[0115] Referring to FIG. 30, further details of interconnect 440
are shown. Seal 442 has an exterior wall 446 for surrounding
electrical contacts 448 (in this case four), and interior walls 450
for isolating electrical contacts 448 from each other. Rim 452
formed on the transmitter housing 330 surrounds the base 454 of
seal 442 to prevent it from collapsing outward when compressed.
[0116] Referring to FIG. 31, an enlarged partial view of FIG. 30 is
shown with seal 442 and one spring removed for clarity. Electrical
contacts 448 are preferably constructed from compression springs
456 mounted on connector lugs 458. Lugs 458 are stamped rearward on
their edges to form protrusions 460 that retain springs 456.
Alternately or in conjunction with this stamping, plastic rings
(not shown) can be melted over the base of each spring 456 for
attaching it to its respective lug 458. Connector lugs 458 can
protrude through slots in transmitter housing 330, or be insert
molded integral with the plastic housing 330 when it is molded.
[0117] Referring to FIG. 32, and enlarged perspective view of the
seal 442 is shown. It has been discovered through experimentation
that two lips 462 of equal height along the distal edge of exterior
wall 446 provide the best seal from exterior elements. Good
isolation between electrical contacts 448 is best achieved by
having interior walls 450 with a height equal to that of lips 462.
Recesses 464 should be sized large enough so that seal 442 does not
interfere with the movement of springs 456 when seal 442 and
springs 456 are compressed. In the preferred embodiment, the distal
face of seal 442 defined by lips 462 is formed at a 1 degree angle
to match the draft angle of mount end stop 444.
[0118] Seal 442 is preferably made of shore A 30 durometer
compression molded silicone. It is envisioned that seal 442 can be
shortened in the axial direction (parallel to springs 456) to
reduce the force required to compress it when attaching transmitter
330 to mount 312. Best results for fastening seal 442 to
transmitter housing 330 have been achieved with double sided
adhesive tape 320, silicone adhesive on one side and acrylic
adhesive on the other for sticking to the PC-ABS blend of the
transmitter housing 330, such as product number 9731 manufactured
by 3M Company of St. Paul, Minn. Springs 456 are preferably made
from gold-plated beryllium copper so as to deter galvanic current
effects. Preferably, main surface 346 of sensor 314 that contacts
seal 442 has a uniform thickness dielectric coating with a window
in it (i.e. no dielectric) where springs 456 contact sensor 314. An
interconnect 440 constructed as described above remains water proof
when submerged to a depth of at least 1 meter for 45 minutes.
[0119] To increase the reliability of sensor insertion, the
following enhancements can be added to the inserter kit 300
described above. First, a sensor flap 466, as shown in FIG. 25, can
be formed along the top edge of sensor 314. When sensor 314 reaches
the extended, delivered position as shown in FIG. 23, flap 466
catches on bottom edge 468 of base 344, shown in FIG. 19, to ensure
that sensor 314 separates from introducer 340 as shuttle 338
returns upward to the retracted position. Adhesive can also be
located on the bottom of orthogonal sensor surface 356 to ensure
that sensor 314 adheres to the sensor contact portion 428 on the
top of adhesive mount tape 320, as shown in FIG. 16.
[0120] Referring to FIGS. 33A and 33B, actuator button 324' can be
made easier for elderly patients to push by anchoring the upper end
of drive spring 336 on a housing bridge 470 instead of button 324.
This change also makes the insertion force of inserter 310 more
consistent, and allows stronger spring forces to be used if
desired. Bridge 470 spans across opening 376' and divides it into
two openings 472 in the top of housing 334'. The top portion of
button 324' is bifurcated into two protrusions 474 that each extend
through an opening 472. A clearance hole (not shown) is provided
through the center of button 324' to allow drive spring 336 to pass
through and secure around a post (not shown) depending from the
bottom center of bridge 470.
[0121] Safety lock key 476 can be provided to prevent actuator
button 324' from being pressed until key 476 is removed. Aperture
478 is provided in the top center of bridge 470 for receiving boss
480 located at the bottom of key 476, thereby allowing key 476 to
rotate. When key handle 482 is rotated perpendicular to button
protrusions 474 as shown, two opposing perpendicular fins 484 on
key 476 swing into inwardly facing slots (not shown) on the inside
of protrusions 474 and prevent button 324' from being actuated.
When key handle 482 and fins 484 are rotated parallel to button
protrusions 474 such that fins 484 disengage therefrom, key 476 can
be removed and button 324' can then be actuated. Other than these
modifications, this inserter kit 300' functions the same as the
embodiment previous described.
[0122] To provide an easier and more consistent release of shuttle
338 by actuator button 324 or 324', it is envisioned that less
aggressive finger engagement with stops 386 can be employed, or the
above designs can be modified to have a single, more centrally
located shuttle release finger (not shown) instead of the two
outboard fingers 412 shown.
[0123] The present invention should not be considered limited to
the particular examples described above. Various modifications,
equivalent processes, as well as numerous structures to which the
present invention may be applicable and which fall within the
general scope of the invention will be readily apparent to those of
skill in the art to which the present invention is directed upon
review of the instant specification.
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