U.S. patent application number 15/060106 was filed with the patent office on 2016-06-23 for on-body medical device securement.
The applicant listed for this patent is ABBOTT DIABETES CARE INC.. Invention is credited to Marc Barry Taub.
Application Number | 20160174881 15/060106 |
Document ID | / |
Family ID | 40509150 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160174881 |
Kind Code |
A1 |
Taub; Marc Barry |
June 23, 2016 |
ON-BODY MEDICAL DEVICE SECUREMENT
Abstract
Devices and methods for maintaining a medical device on-body are
provided. Embodiments include medical device securement systems
having first and second on-body securement elements. Also provided
are systems and kits for use maintaining a medical device
on-body.
Inventors: |
Taub; Marc Barry; (Mountain
View, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ABBOTT DIABETES CARE INC. |
Alameda |
CA |
US |
|
|
Family ID: |
40509150 |
Appl. No.: |
15/060106 |
Filed: |
March 3, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14279284 |
May 15, 2014 |
9326727 |
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15060106 |
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13118441 |
May 29, 2011 |
8734344 |
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14279284 |
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12610237 |
Oct 30, 2009 |
7951080 |
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13118441 |
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11344434 |
Jan 30, 2006 |
7736310 |
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12610237 |
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Current U.S.
Class: |
600/309 |
Current CPC
Class: |
A61B 5/145 20130101;
A61B 5/14865 20130101; A61B 5/6833 20130101; A61B 5/14532 20130101;
A61B 5/14546 20130101 |
International
Class: |
A61B 5/145 20060101
A61B005/145; A61B 5/00 20060101 A61B005/00 |
Claims
1-31. (canceled)
32. A method for positioning a device comprising a non-adhesive
backing having a first surface and a second surface, wherein the
first surface of the non-adhesive backing comprises an adhesive
forming an adhesive portion, and wherein the first surface also has
a non-adhesive portion, the method comprising: positioning the
non-adhesive portion over a medical device, wherein the
non-adhesive portion is sized and configured so that the medical
device is not contacted with the adhesive portion when the
non-adhesive portion is positioned over the medical device.
33. The method of claim 32, further comprising removing a release
layer adjacent to the adhesive portion.
34. The method of claim 32, further comprising removing a casting
layer adjacent to the second surface of the non-adhesive
backing.
35. The method of claim 32, wherein the adhesive portion is
opaque.
36. The method of claim 32, wherein the non-adhesive portion
comprises an opening and a transparent shield covering the
opening.
37. The method of claim 36, wherein the transparent shield is
compressible.
38. The method of claim 32, wherein the medical device includes one
or more of sensor electronics, an RF receiver unit, a data
monitoring device, an infusion device, or a remote control
unit.
39. A method, comprising: attaching a first side of a first
securement element to a body part and a second side of the first
securement element to an on-body control unit; and placing a second
securement element about the on-body control unit such that the
on-body control unit is secured in place on the body part with the
first securement element and the second securement element.
40. The method of claim 39, wherein the second securement element
comprises: a first side and a second side; a plurality of peelable
release layers adjacent to the first side; and a removable layer
adjacent to the second side.
41. The method of claim 40, further comprising peeling away a first
release layer with one or more other release layers still in
contact with the second securement element.
42. The method of claim 41, further comprising removing the one or
more other release layers after the second securement element is
positioned around the on-body control unit.
43. The method of claim 41, further comprising removing the
removable layer before or after removal of the one or more other
release layers.
44. The method of claim 39, wherein the second securement element
includes a hole configured to be positioned over the sensor
electronics.
45. The method of claim 39, wherein the second side of the second
securement element is opposite the first side of the second
securement element.
46. The method of claim 39, further comprising using a fastening
strap to tighten the second securement element.
47. The method of claim 39, further comprising providing mild
compression of the body part by the second securement element so
that the second securement element does not readily slip off.
48. A method, comprising: securing to a skin surface sensor
electronics having a housing and a sensor extending from the
housing; and positioning a device over a portion of the housing,
wherein the device comprises a non-adhesive backing having a first
surface and a second surface, and an adhesive disposed on at least
a portion of the first surface to form an adhesive portion, wherein
a non-adhesive portion is also present on the first surface, the
non-adhesive portion positionable over a medical device and sized
and configured so that the medical device is not contacted with the
adhesive portion when the non-adhesive portion is positioned over
the medical device, the non-adhesive portion including an opening
and a transparent shield covering the opening.
49. The method of claim 48, wherein the device includes one of a
patch, arm band, or strap.
50. The method of claim 48, wherein the transparent shield is
compressible.
51. The method of claim 48, wherein the adhesive portion is opaque.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 14/279,284, filed May 15, 2014, which is a
continuation of U.S. patent application Ser. No. 13/118,441, filed
May 29, 2011, now U.S. Pat. No. 8,734,344, which is a continuation
of U.S. patent application Ser. No. 12/610,237, filed Oct. 30,
2009, now U.S. Pat. No. 7,951,080, which is a continuation of U.S.
patent application Ser. No. 11/344,434, filed Jan. 30, 2006, now
U.S. Pat. No. 7,736,310, the disclosures of all of which are
incorporated herein by reference in their entireties for all
purposes.
BACKGROUND OF THE INVENTION
[0002] There are many instances in which it is necessary to
maintain a medical device "on-body", i.e., secured to a body part
of a patient, e.g., the arm, abdomen, or elsewhere. One such
instance is maintaining a component of an analyte monitoring
system, e.g., a continuous analyte monitoring system, on the skin
of a patient.
[0003] For example, monitoring of the level of glucose or other
analytes, such as lactate or oxygen or the like, in certain
individuals is vitally important to their health. The monitoring of
glucose level 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 sugar is needed
to raise the level of glucose in their bodies. In this regard,
devices and systems have been developed for continuous or automatic
monitoring of analytes, such as glucose, in the blood stream or in
interstitial fluid. Many of these analyte measuring devices include
a glucose sensor that is configured so that at least a portion of
the sensor is positioned below the epidermis, e.g., in a blood
vessel or in the subcutaneous tissue of a patient. The sensor
communicates information about the glucose level to a component
positioned above the skin, where in certain embodiments the
component is intended to be maintained on the skin of the
patient.
[0004] Despite techniques that have been developed to maintain
analyte monitoring components and other medical devices on-body,
the component may still become dislodged from its fixed position on
the skin, e.g., during vigorous exercise, or the by weakening of
the adhesive attaching the components on-body over time, and the
like. This dislodgement may be a mere inconvenience, or may have
severe consequences, e.g., if the dislodgement goes unnoticed for a
substantial period of time during which glucose information is
prevented from being obtained. Furthermore, the mere possibility of
dislodgement is a constant worry to the user.
[0005] As interest in maintaining medical devices, e.g., continuous
analyte monitoring devices, in a fixed position on a skin surface
continues, there is interest in devices and methods for attaching
such device to skin.
SUMMARY OF THE INVENTION
[0006] Generally, the present invention relates to methods and
devices for maintaining a medical device on-body. In certain
embodiments, the present invention relates to the continuous and/or
automatic in vivo monitoring of the level of an analyte using an
analyte sensor and more specifically, devices and methods for
maintaining a component of a continuous or automatic analyte
sensing system adjacent a body part of a patient, where the analyte
sensors include those in which at least a portion of the sensor is
positioned partially beneath the epidermal layer of skin. The
subject invention is further described with respect to analyte
monitoring devices (also referred to herein as "sensors", "analyte
sensing devices", and the like) and analyte monitoring systems for
exemplary purposes only, where such description is in no way
intended to limit the scope of the invention. It is understood that
the subject invention is applicable to any medical device in which
at least a portion of the device is intended to be maintained in
place on a patient.
[0007] Embodiments include devices and methods for maintaining
medical devices, e.g., on-body analyte sensor control units, in
place and include one or more on-body securement elements. In
certain embodiments, first and second on-body securement elements
are employed, where the two elements are used together to maintain
a medical device such as an on-body sensor control unit in place on
a patient. First and second on-body securement elements may be used
in a layered construction such that at least a portion of a medical
device of interest is sandwiched between the two securement
elements to hold the medical device on a body part.
[0008] One or both elements may include adhesive for attachment to
skin and/or to the other element and/or the medical device (e.g.,
an on-skin sensor control unit). In certain embodiments, an on-body
securement element includes an adhesive area and a non-adhesive
area. The non-adhesive area may be an opening in the securement
element, a pocket or other surface or the like that does not have
adhesive. The area that does not include adhesive may approximate
the size and shape of at least a portion of the medical device to
be maintained in place with the securement element so that the
non-adhesive area may encompass the medical device. In embodiments
that include an opening, the opening is positionable around the
medical device so as not to completely cover it.
[0009] Embodiments include on-body securement elements that are
easy to use, e.g., that are easy to position on a body part even in
instances in which the area of the body part on which it is desired
to position the medical device is not within the direct line of
site of the individual performing the positioning. In certain
embodiments, a securement element may include one or more release
liners adapted to facilitate ease of use, where in some embodiments
a plurality of release liners are included and arranged for easy
removal from, and positioning of, the securement element.
[0010] Also provided are systems and kits.
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 shows a block diagram of an exemplary embodiment of
an analyte monitor using an implantable analyte sensor, according
to one embodiment of the invention;
[0013] FIG. 2 is a cross-sectional view of an embodiment of an
on-skin sensor control unit, according to one embodiment of the
invention;
[0014] FIG. 3 is a top view of a base of the on-skin sensor control
unit of FIG. 2;
[0015] FIG. 4 is a bottom view of a cover of the on-skin sensor
control unit of FIG. 2;
[0016] FIG. 5A is a block diagram of an embodiment of an on-skin
sensor control unit, according to one embodiment of the
invention;
[0017] FIG. 5B is a block diagram of an embodiment of an on-skin
sensor control unit, according to one embodiment of the
invention;
[0018] FIG. 6 is a perspective view of the on-skin sensor control
unit of FIG. 2 on the skin of a patient;
[0019] FIG. 7A is a top view of one embodiment of an on-skin sensor
control unit, according to one embodiment of the invention;
[0020] FIG. 7B is a top view of one embodiment of a mounting unit
of the on-skin sensor control unit of FIG. 7A;
[0021] FIG. 8A is a top view of another embodiment of an on-skin
sensor control unit and a sensor, according to one embodiment of
the invention;
[0022] FIG. 8B is a top view of one embodiment of a mounting unit
of the on-skin sensor control unit of FIG. 8A;
[0023] FIG. 8C 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. 8A;
[0024] FIG. 8D is a bottom view of the housing of FIG. 8C;
[0025] FIG. 9A is an exemplary embodiment of an on-body securement
patch according to one embodiment of invention;
[0026] FIG. 9B is an exemplary embodiment of an on-body securement
patch that includes a medical device placement area according to
one embodiment of the invention;
[0027] FIG. 10A is an exemplary embodiment of an on-body securement
band according to one embodiment of the subject invention;
[0028] FIG. 10B is an exemplary embodiment of an on-body securement
band that includes a medical device placement area, according to
one embodiment of the subject invention;
[0029] FIG. 11 is an exemplary embodiment of an on-body securement
band or cuff, according to one embodiment of the subject
invention;
[0030] FIG. 12A is an exemplary embodiment of a release liner
protective system protecting an adhesive containing a body
securement element, according to one embodiment of the subject
invention, and FIG. 12B shows the adhesive containing-securement
element with release liner system thus removed, positioned about an
on-body control unit mount;
[0031] FIG. 13 is a top view of one embodiment of an analyte
sensor, according to one embodiment of the invention;
[0032] FIG. 14A is a cross-sectional view of the analyte sensor of
FIG. 13;
[0033] FIG. 14B is a cross-sectional view of another embodiment of
an analyte sensor, according to one embodiment of the
invention;
[0034] FIG. 15A is a cross-sectional view of another embodiment of
an analyte sensor, according to one embodiment of the
invention;
[0035] FIG. 15B is a cross-sectional view of a fourth embodiment of
another embodiment of a sensor, according to one embodiment of the
invention;
[0036] FIG. 16 is a cross-sectional view of another embodiment of
an analyte sensor, according to one embodiment of the
invention;
[0037] FIG. 17 is an expanded top view of a tip-portion of the
analyte sensor of FIG. 16;
[0038] FIG. 18 is an expanded bottom view of a tip-portion of the
analyte sensor of FIG. 16;
[0039] FIG. 19 is a side view of the analyte sensor of FIG. 13;
and
[0040] FIG. 20 is a block diagram of one embodiment of a
receiver/display unit, according to one embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Before the present invention is described, it is to be
understood that this invention is not limited to particular
embodiments described, as such may, of course, vary. It is also to
be understood that the terminology used herein is for the purpose
of describing particular embodiments only, and is not intended to
be limiting, since the scope of the present invention will be
limited only by the appended claims.
[0042] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limit of that range and any other stated or intervening
value in that stated range, is encompassed within the invention.
The upper and lower limits of these smaller ranges may
independently be included in the smaller ranges as also encompassed
within the invention, subject to any specifically excluded limit in
the stated range. Where the stated range includes one or both of
the limits, ranges excluding either or both of those included
limits are also included in the invention.
[0043] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can also be used in the practice or testing of the present
invention, the preferred methods and materials are now
described.
[0044] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise.
[0045] "May" refers to optionally, and when two or more items (for
example, elements or processes) are referenced by an alternative
"or", this indicates that either could be present separately or any
combination of them could be present together except where the
presence of one necessarily excludes the other or others.
[0046] Any recited method can be carried out in the order of events
recited or in any other order which is logically possible.
Reference to a singular item, includes the possibility that there
are plural of the same item present.
[0047] As will be apparent to those of skill in the art upon
reading this disclosure, each of the individual embodiments
described and illustrated herein has discrete components and
features which may be readily separated from or combined with the
features of any of the other several embodiments without departing
from the scope or spirit of the present invention.
[0048] The figures shown herein are not necessarily drawn to scale,
with some components and features being exaggerated for
clarity.
[0049] As summarized above, the present invention is related to
devices and methods for maintaining a medical device in place on
the body of a patient. The invention is primarily described herein
with respect to maintaining an analyte sensing device and more
particularly an on-body analyte control unit adapted for use with
an analyte sensor in place on a patient for exemplary purposes
only, where such description is in no way intended to limit the
scope of the invention. It is to be understood that the invention
may be used with a variety of medical devices intended to be
maintained in place on a patient. For example, the subject
invention may be used to secure an infusion set, e.g., of an
insulin pump or the like, in place on the body of a patient.
[0050] The present invention is applicable to any analyte
monitoring system such as those using a sensor wherein at least a
portion of the sensor is positionable beneath the skin of the user
for the in vivo determination of a concentration of an analyte,
such as glucose, lactate, and the like, in a body fluid. Additional
analytes that may be determined include but are not limited to, for
example, acetyl choline, amylase, bilirubin, cholesterol, chorionic
gonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA,
fructosamine, glucose, glutamine, growth hormones, hormones,
ketones, lactate, peroxide, prostate-specific antigen, prothrombin,
RNA, thyroid stimulating hormone, and troponin. The concentration
of drugs, such as, for example, antibiotics (e.g., gentamicin,
vancomycin, and the like), digitoxin, digoxin, drugs of abuse,
theophylline, and warfarin, may also be determined.
[0051] A sensor may be, for example, subcutaneously positionable in
a patient for the continuous or periodic monitoring of an analyte
in a patient's interstitial fluid. This may be used to infer the
glucose level in the patient's bloodstream. The sensors also
include in vivo analyte sensors insertable into a vein, artery, or
other portion of the body containing fluid. These sensors may be
configured for monitoring the level of the analyte over a time
period which may range from minutes, hours, days, weeks, or longer.
Of interest are analyte sensors, such as glucose sensors, that are
capable of providing analyte data for about one hour or more, e.g.,
about a few hours or more, e.g., about a few days of more, e.g.,
about three or more days, e.g., about five days or more, e.g.,
about seven days or more, e.g., about several weeks or months.
[0052] Analyte monitoring systems generally include, at a minimum,
an analyte sensor and a control unit, where in many embodiments the
control unit is intended to be held in place on a body part of the
patient. In certain embodiments, a system may only include a sensor
and control unit. These analyte monitoring systems may be utilized
under a variety of conditions. The particular configuration of a
sensor and other units used in an analyte monitoring system may
depend on the use for which the sensor and system are intended and
the conditions under which the sensor and system will operate. As
noted above, embodiments include a sensor configured for
positioning into the body of a patient or user. The term
"positioning" is meant broadly to include wholly implantable
sensors and sensors in which only a portion of which is positioned
under the skin and a portion of which resides above the skin, e.g.,
for contact to a transmitter, receiver, transceiver, processor,
etc.
[0053] For example, positioning of a sensor may be made in the
arterial or venous systems for direct testing of analyte levels in
blood. Alternatively, a sensor may be positioned 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. Sensors may also be
positioned in other regions of the body to determine analyte levels
in other fluids. Examples of suitable sensors for use in the
analyte monitoring systems of the invention are described herein
and in, for example, U.S. Pat. Nos. 6,134,461, 6,175,752, and
elsewhere.
[0054] FIG. 1 illustrates in block diagram form, an exemplary
embodiment of an analyte monitoring system 40. Analyte monitoring
system 40 includes, at minimum, a sensor 42, at least a portion of
the sensor which is configured for positioning (e.g., subcutaneous,
venous, or arterial positioning) into a patient, and a sensor
control unit 44. Sensor 42 is coupleable to sensor control unit 44
which, as noted above, is intended to be worn by the patient.
Sensor control unit 44 operates sensor 42, including, for example,
providing a voltage across the electrodes of the sensor and
collecting signals from the sensor. In certain embodiments, the
control unit is shaped and sized to be concealable. For example, in
certain embodiments, on-skin sensor control unit 44 has a thin,
oval shape to enhance concealment, as illustrated in FIGS. 3 and 4.
However, other shapes and sizes may be used. On-skin sensor control
unit 44 includes a housing 45, as illustrated in FIGS. 2-4 for
example.
[0055] Sensor control unit 44 may evaluate the signals from sensor
42 and/or transmit the signals to one or more optional
receiver/display units 46, 48 for evaluation. Sensor control unit
44 and/or receiver/display units 46, 48 may display or otherwise
communicate the current level of the analyte. Furthermore, sensor
control unit 44 and/or 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, an electrical shock
may 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] Sensor 42 and the electronic components within on-skin
sensor control unit 44 are coupled via conductive contacts 80. The
one or more working electrodes 58, counter electrode 60 (or
counter/reference electrode), optional reference electrode 62, and
optional temperature probe 66 (see for example FIGS. 13-17) are
attached to individual conductive contacts 80. In some embodiments,
the conductive contacts are provided on the exterior of the housing
(see for example FIGS. 7A and 7B) and in other embodiments the
conductive contacts are provided on the interior of the housing,
e.g., within a hollow or recessed region. In the illustrated
embodiment of FIGS. 2-4, the conductive contacts 80 are provided on
the interior of the on-skin sensor control unit 44.
[0057] The on-skin sensor control unit may include at least a
portion of the electronic components that operate the sensor and
the analyte monitoring device system. One embodiment of the
electronics in the on-skin control unit 44 is illustrated as a
block diagram in FIG. 5A. The electronic components of on-skin
sensor control unit 44 may include a power supply 95 for operating
the on-skin control unit and the sensor, a sensor circuit 97 for
obtaining signals from and operating the sensor, a measurement
circuit 96 that converts sensor signals to a desired format, and a
processing circuit 109 that, at minimum, obtains signals from the
sensor circuit 97 and/or measurement circuit 96 and provides the
signals to an optional transmitter 98. In some embodiments,
processing circuit 109 may also partially or completely evaluate
the signals from the sensor and convey the resulting data to the
optional transmitter 98 and/or activate an optional alarm system 94
(see FIG. 5B) if the analyte level exceeds a threshold. Processing
circuit 109 often includes digital logic circuitry.
[0058] On-skin sensor control unit 44 may optionally contain a
transmitter or transceiver 98 for transmitting the sensor signals
or processed data from processing circuit 109 to a receiver (or
transceiver)/display unit 46, 48; a data storage unit 102 for
temporarily or permanently storing data from processing circuit
109; a temperature probe circuit 99 for receiving signals from and
operating a temperature probe 66; a reference voltage generator 101
for providing a reference voltage for comparison with
sensor-generated signals; and/or a watchdog circuit 103 that
monitors the operation of the electronic components in the on-skin
sensor control unit. Moreover, sensor control unit 44 may include a
bias current generator 105 to correctly bias analog and digital
semiconductor devices, an oscillator 107 to provide a clock signal,
and a digital logic and timing component to provide timing signals
and logic operations for the digital components of the circuit.
[0059] FIG. 5B illustrates a block diagram of another exemplary
on-skin sensor control unit 44 that also includes optional
components such as a receiver (or transceiver) 110 to receive, for
example, calibration data; a calibration storage unit (not shown)
to hold, for example, factory-set calibration data, calibration
data obtained via the receiver 110 and/or operational signals
received, for example, from a receiver/display unit 46, 48 or other
external device; an alarm system 94 for warning the patient; and a
deactivation switch 111 to turn off the alarm system.
[0060] The electronics in the on-skin sensor control unit 44 and
the sensor 42 may be operated using a power supply 95. Sensor
control unit 44 may also optionally include a temperature probe
circuit 99. The output from sensor circuit 97 and optional
temperature probe circuit is coupled into a measurement circuit 96
that obtains signals from sensor circuit 97 and optional
temperature probe circuit 99 and, at least in some embodiments,
provides output data in a form that, for example can be read by
digital circuits.
[0061] In some embodiments, the data from processing circuit 109 is
analyzed and directed to an alarm system 94 (see FIG. 5B) to warn
the user. For example, an alarm may notify a patient of a hypo- or
hyperglycemic event.
[0062] In some embodiments, the data (e.g., a current signal, a
converted voltage or frequency signal, or fully or partially
analyzed data) from processing circuit 109 is transmitted to one or
more receiver/display units 46, 48 using a transmitter 98 in
on-skin sensor control unit 44. The transmitter has an antenna 93,
such as a wire or similar conductor, formed in housing 45.
[0063] In addition to a transmitter 98, an optional receiver 110
may be included in the on-skin sensor control unit 44. In some
cases, transmitter 98 is a transceiver, operating as both a
transmitter and a receiver. Receiver 110 (and/or receiver
display/units 46, 48) may be used to receive calibration data for
the sensor 42. The calibration data may be used by processing
circuit 109 to correct signals from sensor 42. This calibration
data may be transmitted by receiver/display unit 46, 48 or from
some other source such as a control unit in a doctor's office. The
on-skin sensor control unit 44 may include an optional data storage
unit 102 which may be used to hold data (e.g., measurements from
the sensor or processed data).
[0064] In certain embodiments, on-skin sensor control unit 44
includes a sensor port through which a sensor enters the
subcutaneous tissue of the patient. A sensor may be inserted into
the subcutaneous tissue of the patient through the sensor port. The
on-skin sensor control unit may then be placed on the skin of the
patient with a sensor being threaded through the sensor port. If
the housing of the sensor has, for example, a base and a cover,
then the cover may be removed to allow the patient to guide the
sensor into the proper position for contact with conductive
contacts 80. Alternatively, if the conductive contacts are within
the housing the patient may slide the sensor into the housing until
contact is made between the contact pads of the sensor and the
conductive contacts. The sensor control unit may have a structure
which obstructs the sliding of the sensor further into the housing
once the sensor is properly positioned with the contact pads in
contact with the conductive contacts. In other embodiments, the
conductive contacts are on the exterior of the housing. In these
embodiments, the patient guides the contacts pads of the sensor
into contact with the conductive contacts of the control unit. In
some cases, a guiding structure may be provided on the housing
which guides the sensor into the proper position. An example of
such a structure includes a set of guiding rails extending from the
housing and having the shape of the sensor.
[0065] One or more receiver/display units 46, 48 may be provided
with the analyte monitoring device 40 for easy access to the data
generated by the sensor 42 and may, in some embodiments, process
the signals from the on-skin sensor control unit 44 to determine
the concentration or level of analyte in the subcutaneous tissue.
The receiver may be a transceiver. Receivers may be palm-sized
and/or may be adapted to fit on a belt or within a bag or purse
that the patient carries.
[0066] The receiver/display units 46, 48, as illustrated in block
form at FIG. 20, typically include a receiver 150 to receive data
from the on-skin sensor control unit 44, an analyzer 152 to
evaluate the data, a display 154 to provide information to the
patient, and an alarm system 156 to warn the patient when a
condition arises. The receiver/display units 46, 48 may also
optionally include a data storage device 158, a transmitter 160,
and/or an input device 162. Data received by the receiver 150 may
then be sent to an analyzer 152.
[0067] The output from the analyzer 152 may be provided to a
display 154. The receiver/display units 46, 48 may also include a
number of optional items such as a data storage unit 158 to store
data, a transmitter 160 which can be used to transmit data, and an
input device 162, such as a keypad or keyboard.
[0068] In certain embodiments, the receiver/display unit 46, 48 is
integrated with a calibration unit (not shown). For example, the
receiver/display unit 46, 48 may, for example, include a
conventional blood glucose monitor. Devices may be used including
those that operate using, for example, electrochemical and
colorimetric blood glucose assays, assays of interstitial or dermal
fluid, and/or non-invasive optical assays. When a calibration of
the implanted sensor is needed, the patient uses the integrated in
vitro monitor to generate a reading. The reading may then, for
example, automatically be sent by the transmitter 160 of the
receiver/display unit 46, 48 to calibrate the sensor 42.
[0069] In certain embodiments, analyte data (processed or not) may
be communicated, e.g., forwarded (such as by communication) to a
remote location such as a doctor's office if desired, and received
there for further use (such as further processing).
[0070] As described, on-skin sensor control unit 44 is intended to
be worn "on-body" by the patient, e.g., attached directly or
indirectly to the skin 75 of the patient, as illustrated for
example in FIG. 6. The subject invention provides methods and
devices for such on-body placement and securement. As described in
greater detail below, certain embodiments include only one on-body
securement element and certain embodiments include at least a first
on-body securement element and a second on-body securement element.
A first securement element may be adapted for attachment to a skin
surface, e.g., may be an adhesive-containing element or the like,
and also to on-skin control unit. For example, a first side may
include adhesive for attachment to skin and a second side may be
adapted for mating with a control unit. A second securement element
may be adapted to be positionable over at least a portion of the
first element, including a first element/control unit structure. In
some embodiments, only one on-body securement elements may be used
or one may be used in certain instances and the other or both may
be used in certain other instances. For example, a first element
may be used for everyday use, and the second element may be
included and used with the first (or used alone) in certain
instances, e.g., vigorous activities such as exercising and the
like.
[0071] Referring again to FIG. 6, on-skin sensor control unit 44
may be attached 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 or by suturing the on-skin
sensor control unit 44 to the skin 75 through suture openings (not
shown) in the sensor control unit 44.
[0072] In other embodiments, a mounting unit 77 is employed to
attach the housing 45 of the on-skin sensor control unit 44 to the
skin 75. Mounting unit 77 may be part of the on-skin sensor control
unit 44 or may be separate. One example of a suitable mounting unit
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 sensor 42 through opening 79 for
electrical contact with the control unit. Alternatively, the sensor
may be inserted through a thin adhesive and into the skin.
[0073] 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. An
adhesive is usually 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, e.g., may be
hypoallergenic adhesive. 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, may 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. Adhesives that may be
used includes, but is not limited to acrylic adhesives, and the
like, e.g., a polyurethane membrane coated with a layer of an
acrylic adhesive such as TEGADERM from 3M Corporation.
[0074] Another embodiment of a mounting unit 77 that may be used in
an on-skin sensor control unit 44 is illustrated in FIGS. 7A and
7B. Mounting unit 77 and housing 45 of on-skin sensor control unit
44 are mounted together in, for example, an interlocking manner, as
shown in FIG. 7A. Mounting unit 77 is formed, for example, using
plastic or polymer materials, including, for example,
polycarbonate, 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.
[0075] The mounting unit 77 may include an adhesive on a bottom
surface to adhere to the skin of the patient or mounting unit 77
used in conjunction with, for example, double-sided adhesive tape
or the like. The mounting unit 77 may include an opening 79 through
which the sensor 42 is inserted, as shown for example in FIG. 7B.
Mounting unit 77 may also include a support structure 220 for
holding a sensor in place and against the conductive contacts 80 of
the on-skin sensor control unit. Mounting unit 77, also,
optionally, includes a positioning structure 222, such as an
extension of material from the mounting unit, that corresponds to a
structure (not shown), such as an opening, on a sensor 42 to
facilitate proper positioning of the sensor, for example, by
aligning the two complementary structures.
[0076] 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 housing 45 of the on-skin sensor control unit 44, as
illustrated in FIG. 8A. The optional cover may contain an adhesive
or other mechanism for attachment to the housing 45 and/or mounting
unit 77. Mounting unit 77 typically includes an opening 49 through
which a sensor 42 is disposed, as shown in FIG. 8B. Opening 49 may
optionally be configured to allow insertion of the sensor 42
through the opening using an insertion device or insertion gun.
Housing 45 of on-skin sensor control unit 44 has a base 74 and a
cover 76, as illustrated in FIG. 8C. A bottom view of housing 45,
as shown in FIG. 8D, illustrates ports 230 through which conductive
contacts (not shown) extend to connect with contact pads on the
sensor 42. A board (not shown) for attachment of circuit components
may optionally be provided within on-skin sensor control unit
44.
[0077] In some embodiments, the adhesive on an on-skin sensor
control unit 44 and/or on any of the embodiments of 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 to the skin of the patient and, at least in
some embodiments, preventing water from penetrating into the sensor
control unit. The use of a water resistant or waterproof adhesive
combined with a water resistant or waterproof housing 45 protects
the components in sensor control unit 44 and the contact between
conductive contacts 80 and sensor 42 from damage or corrosion. An
example of a non-irritating adhesive that repels water is
TEGADERM.
[0078] As described above, in certain embodiments an on-body
securement element may be adapted to be positionable about at least
a portion of the control unit and may be used in addition to, or
instead of, any securement element described herein. For example, a
first on-body securement element may be used that is attachable to
a body part, e.g., includes an adhesive for attachment to the skin.
The adhesive may be directly on the control unit or may be a
separate component, e.g., a mounting unit or an adhesive patch to
which a mounting unit/control unit is attachable, etc. The on-body
securement element, if it includes adhesive, may be adapted to
adhesively attach to the skin and/or mount and/or control unit,
and/or a first adhesive patch positioned adjacent the skin and upon
which the mount and/or control unit resides, e.g., in certain
embodiments with a control unit held therebetween.
[0079] A second securement element may be included and may be a
securement patch or band and may or may not include adhesive. FIGS.
9-11 show exemplary embodiments of on-body securement elements.
Securement elements 300 and 310 of FIGS. 9A and 9B, respectively,
are in the form of securement patches, e.g., adhesive patches. The
adhesive patches may include adhesive on a backing layer.
Securement elements 400 and 410 of FIGS. 10A and 10B, respectively,
are in the form of securement bands and embodiment 500 of FIG. 11
is in the form of a securement strap or cuff. Elements 300 and 400
of FIGS. 9A and 10A, respectively, are substantially the same as
elements 310 and 410 of FIGS. 9B and 10B, respectively, except the
embodiments of FIGS. 9A and 10A do not include a control unit area
315 and 415, respectively (it is understood that embodiment 500 of
FIG. 11 may also include a control unit area (not shown)), which
may include one or more of: a hole, a covering such as a
transparent shield (e.g., non-adhesive), a recess or pouch, or is
otherwise a non-adhesive area. In those embodiments in which
control unit area 315 is an opening in the securement element, the
opening provides an area through which a control unit may be
positioned so that the control unit is not completely covered by
the on-body securement element. In certain embodiments, the
securement element may be opaque except for an opening covered with
a transparent shield, the shield configured to be positioned over a
control unit. The shield may be compressible to allow a user to
actuate buttons, knobs, thumbwheels, etc., if provided on the
control unit and which may be positioned beneath the shield.
[0080] A non-adhesive-including area may be particularly relevant
if an on-body securement element includes an adhesive-including
area. An opening (or otherwise non-adhesive surface) provides an
adhesive-free area which prevents accumulation of adhesive residue
on the control unit surface, improving moisture transmission rates
and eliminating entrapped pockets that may serve as potential sites
for water accumulation. An opening or recess provides a further
advantage of providing an easily identifiable reference point for
registering the securement element with a control unit so that it
may be correctly and easily positioned about the control unit even
in instances in which the control unit is not within the direct
line of site of the patient. This may be particularly important for
patients with diminished hand-eye coordination and/or manual
dexterity and/or visual capabilities.
[0081] In certain embodiments, an on-body securement element
provides mild compression of a body part so that the element does
not readily slip off of the patient. The on-body securement element
may be further tightened using a fastening strap or other mechanism
which cinches the element tighter onto the arm.
[0082] In embodiments in which the on-body securement element is a
patch, e.g., an adhesive-including patch, as shown for example in
FIGS. 9A and 9B, securement patches 300 and 310 include support
312. Certain embodiments may include adhesive. For example, a first
on-body securement element in the form of a first adhesive patch
attachable to the skin may be employed. The first patch may be
adapted for retaining a mounting unit and/or control unit and may
be sized to include an extended edge so that once a mount and/or
control unit is positioned thereupon, a perimeter edge is available
for attachment to a second adhesive patch. Accordingly, a second
adhesive patch is positioned either completely over the control
unit, e.g., in the case of the embodiments of FIG. 9A, or
positioned around the control unit rather than over it (but
positioned about the mounting unit or adhesive patch carrying a
mounting unit)--using the extended edge of the first adhesive patch
as a point of attachment between the first and second patches.
[0083] Other securement embodiments may be in the form of an arm
band or strap that partially or completely encircle a body part
such as an arm, leg, wrist, abdomen, etc., as shown for example in
FIGS. 10A, 10B and 11. Analogous to a patch securement element, an
arm band or strap securement, if inclusive of adhesive, may be
adapted to adhesively attach to the skin and/or mount and/or
control unit, and/or a first adhesive patch positioned adjacent the
skin and upon which the mount and/or control unit resides.
[0084] In certain embodiments, an on-body securement element may be
a tubular structure such as securement bands 400 and 410 having
supports 412, as shown in FIGS. 10A and 10B, e.g., elasticized
tubular elements. In certain embodiments, a securement element may
be in the form of a strap or cuff such as securement element 500
having support 512, as shown in FIG. 11. Securement element 500 may
include joinable ends 502 and 504 for forming a tubular structure.
Opposing ends 502 and 504 may include fasteners 510 to connect the
opposing ends together to form a tubular structure and surround a
body part of a patient. Fasteners that may be used include but are
not limited to snaps, buttons, zippers, hook-and-loop fastener,
laces, Velcro.RTM., latches, etc. The fastening system may bring
the opposing ends of a securement element in proximity to permit
coaptation.
[0085] In addition to the support layer and adhesive layer (if
present), additional layers may be included. For example, a
removable layer may be positioned adjacent to one or more surfaces
(e.g., adjacent an adhesive layer surface and/or casting layer
surface) of a securement element for protection of the securement
element from the environment. For example, a securement element
having an adhesive surface may include a peelable release liner
adjacent the adhesive surface to maintain the integrity of the
adhesive until use and/or a casting layer. In certain embodiments,
a securement element may be in the form of a sandwich configuration
such as a laminate or the like. A securement element may include
adhesive disposed on a backing, the adhesive/backing structure may
be sandwiched between two removable layers: a removable release
liner adjacent the adhesive and a removable casting layer adjacent
the backing. The materials thereof may be any suitable materials,
including materials described herein and others. Any suitable
materials may be used, where in certain embodiments a release liner
is a polyester such as PET or PP, and the like, or siliconized
paper (e.g., siliconized Kraft paper), or the like, an adhesive is
polyacrylate, silicone, PIB, natural or synthetic rubber or the
like, a backing is a polyurethane film, or the like, in the form of
films, foams, nonwovens, etc., and the casting layer is PE, or the
like.
[0086] In certain embodiments, the removable layer(s) may have
greater rigidity than the securement element with which it is
employed. This relative rigidity may provide structural stability
and facilitate peeling-away of the layer from the securement
element by the patient. A removable layer such as a release liner
may include tabs or the like graspable by a patient.
[0087] In certain embodiments, a plurality of release liners is
used. A plurality of release liners may increase the ease of
removal of the release liners from the securement element and the
ease of use of the securement element by providing one-handed,
self-application of a securement element.
[0088] An embodiment of a release liner system 600 having a
plurality of release liners 604a, 604b, 604c, and 604d is shown in
FIGS. 12A and 12B. FIG. 12A shows a release liner protective system
600 protecting a surface an adhesive surface 310b of securement
element 310, e.g., adhesive 310b may be present on backing layer
310a, according to the subject invention. Front and back faces are
shown in FIG. 12B, right and left figures respectively.
Accordingly, left FIG. 12B shows securement element 310 with
release liner system 600 thus removed and positioned about mounting
unit 77, and more specifically the adhesive of securement element
310 is adhered to an adhesive patch (not shown) that retain
mounting unit 77. Mounting unit 77 is positioned within control
unit area 315.
[0089] Release liner system 600 may be used with any securement
element, herein shown in FIGS. 12A and 12B as used with element 310
of FIG. 9B for exemplary purposes. Removable system 600 of peelable
release layers 604 are adjacent one (adhesive) side 310b of element
310 and removable layer 602 is adjacent a second, opposite
(backing) side 310a. Side 310b includes a plurality of release
liners 604a, 604b, 604c and 604d, wherein more or less may be
used.
[0090] In use, an on-body control unit may be first attached to a
body part of a patient, e.g., using a first securement element in
the form of an adhesive patch which, at one side, is attached to a
body part and at a second side is attached to a mounting unit and
control unit. To secure the control unit in place, a patient may
hold second securement element 310 carrying release liner system
600 with one hand, e.g., with a right hand to apply to the left
arm, and vice versa. A first release liner (e.g., release liner
604a) may be peeled away from securement element 310, e.g., using a
tab or the like, and securement element 310, with the other release
liners still in contact therewith, may be positioned about the
control unit so that the hole of the securement element/release
liner system is positioned around the control unit. Once positioned
over the control unit, remaining release liners 604b, 604c . . .
may be easily removed from securement element 310. Removable layer
602, if present, may be removed at any convenient time, e.g.,
before or after removal of release liner 604.
[0091] First and/or second on-body securement elements may be made
from any suitable material where in many embodiments the material
is selected for prolonged contact with skin with minimal skin
irritation, as noted above. The material may be conformable to a
patient's body part. Materials include but are not limited to those
described herein and polyurethane; polyolefin, such as polyethylene
and polypropylene; polyvinylchloride; ethylene vinyl acetate; woven
fabrics; nonwoven fabrics; and the like, and may be perforated or
non-perforated. In certain embodiments, the material may be
perspiration-absorbing material. For example, elements may include
a backing with an adhesive layer thereon. The backing may be
fabricated from one or more of these materials.
[0092] As described, the subject invention, in accordance with
various embodiments, may be used to secure any medical device to a
body part and has been described primarily with reference to
securing on-body analyte sensor control units to a body part. In
such embodiments, any suitable analyte sensor may be employed,
where exemplary analyte sensors are now described, where such
description is in no way intended to limit the scope of the
invention as it will be apparent that the subject invention is
applicable to any analyte sensor and sensor system.
[0093] FIG. 13 shows an exemplary embodiment of an analyte sensor
42. Sensor 42 includes at least one working electrode 58 and a
substrate 50. The sensor 42 may also include at least one counter
electrode 60 (or counter/reference electrode) and/or at least one
reference electrode 62 (see for example FIG. 18). The counter
electrode 60 and/or reference electrode 62 may be formed on the
substrate 50 or may be separate units. For example, the counter
electrode and/or reference electrode may be formed on a second
substrate which is also implantable in the patient or, for some
embodiments of the sensors, the counter electrode and/or reference
electrode may be placed on the skin of the patient with the working
electrode or electrodes being implanted into the patient. The use
of an on-the-skin counter and/or reference electrode with an
implantable working electrode is described in, e.g., U.S. Pat. No.
5,593,852.
[0094] The working electrode or electrodes 58 are formed using
conductive materials 52. The counter electrode 60 and/or reference
electrode 62, as well as other optional portions of the sensor 42,
such as a temperature probe 66 (see for example FIG. 18), may also
be formed using conductive material 52. The conductive material 52
may be formed over a smooth surface of the substrate 50 or within
channels 54 (see FIG. 14A) formed by, for example, embossing,
indenting or otherwise creating a depression in the substrate
50.
[0095] A sensing layer 64 (see for example FIGS. 14A and 14B) may
be provided proximate to or on at least one of the working
electrodes 58 to facilitate the electrochemical detection of the
analyte and the determination of its level in the sample fluid,
particularly if the analyte cannot be electrolyzed at a desired
rate and/or with a desired specificity on a bare electrode.
[0096] In addition to the electrodes 58, 60, 62 and the sensing
layer 64, the sensor 42 may also include optional components such
as one or more of the following: a temperature probe 66 (see for
example FIGS. 16 and 18), a mass transport limiting layer 74, e.g.,
a matrix such as a membrane or the like, (see for example FIG. 19),
a biocompatible layer 75 (see for example FIG. 19), and/or other
optional components, as described below. Each of these optional
items enhances the functioning of and/or results from sensor 42, as
discussed below.
[0097] The substrate 50 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 may be determined, at least in part, based on the
desired use of the sensor and properties of the materials.
[0098] In addition to considerations regarding flexibility, it is
often desirable that a sensor 42 should have a substrate 50 which
is non-toxic. Substrate 50 may be one that is approved by one or
more appropriate governmental agencies or private groups for in
vivo use. Although substrate 50 in at least some embodiments has
uniform dimensions along the entire length of the sensor, in other
embodiments substrate 50 has a distal end 67 and a proximal end 65
with different widths 53, 55, respectively, as illustrated for
example in FIG. 13.
[0099] At least one conductive trace 52 may be formed on the
substrate for use in constructing a working electrode 58. In
addition, other conductive traces 52 may be formed on the substrate
50 for use as electrodes (e.g., additional working electrodes, as
well as counter, counter/reference, and/or reference electrodes)
and other components, such as a temperature probe. The conductive
traces 52 may extend most of the distance along a length 57 of the
sensor 42, as illustrated for example in FIG. 13, although this is
not necessary. The placement of the conductive traces 52 may depend
on the particular configuration of the analyte monitoring system
(e.g., the placement of control unit contacts and/or the sample
chamber in relation to the sensor 42). For implantable sensors,
particularly subcutaneously implantable sensors, the conductive
traces may extend close to the tip of the sensor 42 to minimize the
amount of the sensor that must be implanted.
[0100] The conductive traces may be formed using a conductive
material 56 such as carbon (e.g., graphite), a conductive polymer,
a metal or alloy (e.g., gold or gold alloy), or a metallic compound
(e.g., ruthenium dioxide or titanium dioxide), and the like.
Conductive traces 52 (and channels 54, if used) may be formed with
relatively narrow widths. In embodiments with two or more
conductive traces 52 on the same side of the substrate 50, the
conductive traces 52 are separated by distances sufficient to
prevent conduction between the conductive traces 52. The working
electrode 58 and the counter electrode 60 (if a separate reference
electrode is used) may be made using a conductive material 56, such
as carbon.
[0101] Reference electrode 62 and/or counter/reference electrode
may be formed using conductive material 56 that is a suitable
reference material, for example silver/silver chloride or a
non-leachable redox couple bound to a conductive material, for
example, a carbon-bound redox couple.
[0102] The electrical contact 49 may be made using the same
material as the conductive material 56 of conductive traces 52 or
alternatively, may be made from a carbon or other non-metallic
material, such as a conducting polymer.
[0103] A number of exemplary electrode configurations are described
herein, however, it will be understood that other configurations
may also be used. In certain embodiments, e.g., illustrated in FIG.
14A, the sensor 42 includes two working electrodes 58a, 58b and one
counter electrode 60, which also functions as a reference
electrode. In another embodiment, the sensor includes one working
electrode 58a, one counter electrode 60, and one reference
electrode 62, as shown for example in FIG. 14B. Each of these
embodiments is illustrated with all of the electrodes formed on the
same side of the substrate 50.
[0104] Alternatively, one or more of the electrodes may be formed
on an opposing side of the substrate 50. In another embodiment, two
working electrodes 58 and one counter electrode 60 are formed on
one side of the substrate 50 and one reference electrode 62 and two
temperature probes 66 are formed on an opposing side of the
substrate 50, as illustrated in FIG. 16. The opposing sides of the
tip of this embodiment of the sensor 42 are illustrated in FIGS. 17
and 18.
[0105] Some analytes, such as oxygen, may be directly
electrooxidized or electroreduced on the working electrode 58.
Other analytes, such as glucose and lactate, require the presence
of at least one electron transfer agent and/or at least one
catalyst to facilitate the electrooxidation or electroreduction of
the analyte. Catalysts may also be used for those analytes, such as
oxygen, that can be directly electrooxidized or electroreduced on
the working electrode 58. For these analytes, each working
electrode 58 has a sensing layer 64 formed proximate to or on a
working surface of the working electrode 58. In many embodiments,
the sensing layer 64 is formed near or on only a small portion of
the working electrode 58, e.g., near a tip of sensor 42.
[0106] The sensing layer 64 includes one or more components
designed to facilitate the electrolysis of the analyte. Sensing
layer 64 may be formed as a solid composition of the desired
components (e.g., an electron transfer agent and/or a catalyst).
These components may be non-leachable from the sensor 42 and may be
immobilized on the sensor 42. For example, the components may be
immobilized on a working electrode 58. Alternatively, the
components of the sensing layer 64 may be immobilized within or
between one or more membranes or films disposed over the working
electrode 58 or the components may be immobilized in a polymeric or
sol-gel matrix. Examples of immobilized sensing layers are
described in, e.g., U.S. Pat. Nos. 5,262,035; 5,264,104; 5,264,105;
5,320,725; 5,593,852; and 5,665,222; and PCT Patent Application No.
U.S. 1998/002403 entitled "Electrochemical Analyte Sensors Using
Thermostable Soybean Peroxidase", filed on Feb. 11, 1998, published
as WO-1998/035053.
[0107] Sensors having multiple working electrodes 58a may also be
used, e.g., and the signals therefrom may be averaged or
measurements generated at these working electrodes 58a may be
averaged. In addition, multiple readings at a single working
electrode 58a or at multiple working electrodes may be
averaged.
[0108] In many embodiments, sensing layer 64 contains one or more
electron transfer agents in contact with the conductive material 56
of working electrode 58, as shown for example in FIGS. 14A and 14B.
Useful electron transfer agents and methods for producing them are
described in, e.g., U.S. Pat. Nos. 5,264,104; 5,356,786; 5,262,035;
5,320,725; 6,175,752; 6,329,161; and elsewhere. The sensing layer
64 may also include a catalyst which is capable of catalyzing a
reaction of the analyte. The catalyst may also, in some
embodiments, act as an electron transfer agent.
[0109] To electrolyze the analyte, a potential (versus a reference
potential) is applied across the working and counter electrodes 58,
60. When a potential is applied between the working electrode 58
and the counter electrode 60, an electrical current will flow.
Those skilled in the art will recognize that there are many
different reactions that will achieve the same result; namely the
electrolysis of an analyte or a compound whose level depends on the
level of the analyte.
[0110] A variety of optional items may be included in a sensor. One
optional item is a temperature probe 66 (see for example FIG. 18).
One exemplary temperature probe 66 is formed using two probe leads
68, 70 connected to each other through a temperature-dependent
element 72 that is formed using a material with a
temperature-dependent characteristic. An example of a suitable
temperature-dependent characteristic is the resistance of the
temperature-dependent element 72. The temperature probe 66 can
provide a temperature adjustment for the output from the working
electrode 58 to offset the temperature dependence of the working
electrode 58.
[0111] The sensors of the subject invention are biocompatible.
Biocompatibility may be achieved in a number of different manners.
For example, an optional biocompatible layer 73 may be formed over
at least that portion of the sensor 42 which is inserted into the
patient, as shown in FIG. 19.
[0112] An interferant-eliminating layer (not shown) may be included
in the sensor 42. The interferant-eliminating layer may include
ionic components, such as Nafion.RTM. or the like, incorporated
into a polymeric matrix to reduce the permeability of the
interferant-eliminating layer to ionic interferants having the same
charge as the ionic components.
[0113] A mass transport limiting layer 71 may be included with the
sensor to act as a diffusion-limiting barrier to reduce the rate of
mass transport of the analyte, for example, glucose or lactate,
into the region around the working electrodes 58. Exemplary layers
that may be used are described for example, in U.S. Pat. No.
6,881,551, and elsewhere.
[0114] A sensor of the subject invention may be adapted to be a
replaceable component in an in vivo analyte monitor, and
particularly in an implantable analyte monitor. As described above,
in many embodiments the sensor is capable of operation over a
period of days or more, e.g., a period of operation may be at least
about one day, e.g., at least about three days, e.g., at least
about five days, e.g., at least about one week or more, e.g., one
month or more. The sensor may then be removed and replaced with a
new sensor.
[0115] The various embodiments of the present invention may also be
employed to maintain a therapeutic agent delivery system on-body,
e.g., an infusion device and/or infusion sets. Embodiments includes
analyte monitoring systems used in sensor-based therapeutic agent
(e.g., insulin) delivery systems, wherein the subject invention is
included to secure one or more components thereof on a body part of
a patient.
[0116] The system may provide a therapeutic agent to counteract the
high or low level of an analyte in response to the signals from one
or more sensors. Alternatively, the system may monitor the drug
concentration to ensure that the drug remains within a desired
therapeutic range. The system may include one or more (e.g., two or
more) sensors, an on-skin sensor control unit and one or more
on-body securement elements, a receiver/display unit, a data
storage and controller module, and a drug administration system. In
some cases, the receiver/display unit, data storage and controller
module, and drug administration system may be integrated in a
single unit. The sensor-based therapeutic agent delivery system may
use data from the one or more sensors to provide necessary input
for a control algorithm/mechanism in the data storage and
controller module to adjust the administration of therapeutic
agent. As an example, a glucose sensor may be used to control and
adjust the administration of insulin.
[0117] Finally, kits for use in practicing the various embodiments
of the subject invention are also provided. The subject kits may
include one or more on-body securement elements as described
herein. Embodiments may also include a sensor and/or a sensor
control unit.
[0118] In addition to one or more of the above-described
components, the subject kits may also include written instructions
for using a sensor and/or on-body securement elements. The
instructions may be printed on a substrate, such as paper or
plastic, etc. As such, the instructions may be present in the kits
as a package insert, in the labeling of the container of the kit or
components thereof (i.e., associated with the packaging or
sub-packaging) etc. In other embodiments, the instructions are
present as an electronic storage data file present on a suitable
computer readable storage medium, e.g., CD-ROM, diskette, etc. In
yet other embodiments, the actual instructions are not present in
the kit, but means for obtaining the instructions from a remote
source, e.g., via the Internet, are provided. An example of this
embodiment is a kit that includes a web address where the
instructions can be viewed and/or from which the instructions can
be downloaded. As with the instructions, this means for obtaining
the instructions is recorded on a suitable substrate.
[0119] In many embodiments of the subject kits, the components of
the kit are packaged in a kit containment element to make a single,
easily handled unit, where the kit containment element, e.g., box
or analogous structure, may or may not be an airtight container,
e.g., to further preserve the one or more sensors and additional
reagents (e.g., control solutions), if present, until use.
[0120] In accordance with one embodiment of the present invention,
mounting units with adhesive skin patches mated with control units
and positioned on body surfaces (such as arm or abdomen) may be
used in conjunction with second on-body securement elements
retained substantially in its original position on the body surface
for approximately 110 hours without substantial dislodgment. In the
aforementioned embodiment, second on-body securement elements in
the form of overbandages may be used. The overbandages include a
casting layer, backing film, adhesive and release liner system, for
example, as shown in to FIG. 12A, where a central through-hole is
provided and sized to accommodate the control unit with a small
clearance to facilitate application.
[0121] The overbandages may be designed to adhere only to the
extended ring of the skin patch of the mounting unit and to provide
increased adhesive area for skin adhesion. In this manner, the
control units remained uncovered by the overbandages, reducing the
likelihood of leaving adhesive residue on the control units.
Moreover, this embodiment provides easier applications (with one
hand and without line-of-sight) as compared to the other bandages.
This may be achieved by the control units serving as lead-ins for
positioning the overbandages, the tabs thereof exposing the
"tack-in-place" spot of adhesive, and the easily removable release
liner peel features.
[0122] In this manner, in one embodiment of the present invention,
easy application and/or removal of overbandages for securing
medical devices such as, for example, analyte sensor in combination
with on-body securement elements is provided. Moreover, in
accordance with the various embodiments of the present invention,
there are provided devices and methods for maintaining a medical
device on-body that provides, among others, ease of use, even in
instances in which the medical device is to be maintained on a body
part that is not within the direct line of site of the patient, and
comfort. Furthermore, the subject invention in various embodiments
provides a patient with a high degree of confidence that the
medical device is securely maintained in position on a body
part.
[0123] While the present invention has been described with
reference to the specific embodiments thereof, it should be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted without departing from the
true spirit and scope of the invention. In addition, many
modifications may be made to adapt a particular situation,
material, composition of matter, process, process step or steps, to
the objective, spirit and scope of the present invention. All such
modifications are intended to be within the scope of the claims
appended hereto.
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