WO2016205098A1

WO2016205098A1 - Wearable sensor devices using isoprene based adhesives

Info

Publication number: WO2016205098A1
Application number: PCT/US2016/037129
Authority: WO
Inventors: Ben Vanmarcke
Original assignee: Avery Dennison Corp
Current assignee: Avery Dennison Corp
Priority date: 2015-06-16
Filing date: 2016-06-13
Publication date: 2016-12-22
Anticipated expiration: 2017-12-16

Abstract

Wireless sensor patches utilizing particular adhesives are described. The patches utilize one or more isoprene based adhesives to adhesively join components of the patch together and form a resulting patch that is resistant to ingress of water or moisture.

Description

Wearable Sensor Devices Using Isoprene Based Adhesives

Cross-Reference to Related Application

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 62/180,157 filed June 16, 2015, which is incorporated herein by reference in its entirety.

Field

[0002] The present subject matter relates to wireless sensor patches and methods of manufacturing and, more particularly, to wireless sensor patches including one or more isoprene based adhesives.

Background

[0003] A wearable sensor device provides information to a user that can be used for assessment of the user's lifestyle in terms of general physical activity, sleep, etc. During wear of a disposable self-adhesive patch, the device will be subjected to various sources of water, including showering, rain, sweat, etc. This requires the various materials and their interfaces within the patch to exhibit a sufficient resistance towards water ingress. Especially when openings are present in the materials, such as when Galvanic Skin Response (GSR) electrodes are exposed along the underside of the device, channels along the perimeter of the electrodes (resulting primarily from surface roughness) will allow water to enter into the device, thereby damaging the electronics. It is therefore desirable to reduce the potential of water ingress into the device.

[0004] Hot melt pressure sensitive adhesives have been used in joining components and manufacturing wearable sensor devices. Hot melt pressure sensitive adhesives can be forced to flow and thereby increase surface area of bonding to a substrate through heat and/or pressure. However, minor changes in the viscosity of the adhesive (typically caused by chemical crosslinking and degradation of the adhesive) may render the heat and/or pressure treatment ineffective. This has been found to be the case with styrene butadiene styrene (SBS) based hot melt adhesives, which are prone to chemical crosslinking upon exposure to excessive heat. Such crosslinking can significantly increase the viscosity of the adhesive and in some applications render the adhesive unable to flow and thereby effectively seal the device. Accordingly, a need remains for new strategies and adhesives for use in forming wearable sensor devices.

Summary

[0005] The difficulties and drawbacks associated with previous approaches are addressed in the present subject matter as follows.

[0006] In one aspect, the present subject matter provides a wireless sensor patch for adhesive attachment to a user's skin. The sensor patch comprises a sensor device including electronics and at least one sensor for detecting a physiological state of a user. The sensor patch also comprises a flexible cover patch overlying the sensor device. The sensor patch additionally comprises a flexible support patch. The support patch defines a first face directed toward the sensor device and an oppositely directed second face. The support patch and the cover patch generally enclose the sensor device. The sensor patch also comprises a skin-friendly adhesive disposed on the second face of the flexible support patch. And, the sensor patch comprises an adhesive tie layer patch disposed between the sensor device and the support patch. The adhesive tie layer includes at least one isoprene based adhesive.

[0007] In another aspect, the present subject matter provides a method of forming a wireless sensor patch that is resistant to water ingress. The method comprises providing (i) a sensor device including electronics and at least one sensor for detecting a physiological state of a user, (ii) a flexible cover patch, (iii) a flexible support patch, and (iv) an adhesive tie layer patch that includes at least one isoprene based adhesive. The method also comprises sealing the sensor device between the flexible cover patch and at least one of the flexible support patch and the adhesive tie layer.

[0008] As will be realized, the subject matter described herein is capable of other and different embodiments and its several details are capable of modifications in various respects, all without departing from the claimed subject matter. Accordingly, the drawings and description are to be regarded as illustrative and not restrictive.

Brief description of the drawings

[0009] Figure 1 schematically illustrates an embodiment of a wireless sensor patch in accordance with aspects of the present subject matter applied to a skin surface of a user.

[0010] Figure 2 is a top schematic view of the wireless sensor patch of Figure 1.

[0011] Figure 3 is a side schematic view of the wireless sensor patch of Figure 1.

[0012] Figure 4 is a bottom schematic view of the wireless sensor patch of Figure 1.

[0013] Figure 5 is an exploded upper perspective schematic view of a wireless sensor patch of Figure 1.

[0014] Figure 6 is a schematic cross sectional view of the wireless sensor patch along line 6-

6 of Figure 5. [0015] Figure 7 is a schematic cross sectional view of the wireless sensor patch along line 7- 7 of Figure 5.

[0016] Figure 8 is a bottom perspective schematic view of a sensor device of the wireless sensor patch of Figure 5.

[0017] Figure 9 is a schematic cross sectional view of the wireless sensor patch along line 9- 9 of Figure 5.

Detailed description of the embodiments

[0018] The present subject matter provides wearable sensor devices that include a skin friendly adhesive envelope, an electronics module, and a protective foam or film covering. The protective film, the electronics module, and the adhesive envelope are joined together using an isoprene based adhesive and in certain embodiments, a double coated, high tack, isoprene based pressure sensitive adhesive tape which exhibits resistance to water and moisture ingress.

[0019] Figure 1 illustrates a wireless sensor patch 10 in accordance with aspects of the present subject matter. The wireless sensor patch 10 can be designed to monitor various parameters of a user 1. For instance, as shown, the wireless sensor patch 10 may be adhered to a skin surface 12 of the user 1. Any of the wireless sensor patches described herein may be adhered to various alternative skin surfaces of the user. For instance, the skin patch may be adhered to the chest of a user (e.g., as shown in Figure 1), on the arm (e.g., on the back of the arm) of the user or various other locations of the user depending on the circumstances and application.

[0020] The wireless sensor patch 10 can include at least one sensor configured to monitor any one or combination of parameters such as physiological condition(s) of a user. For instance, the sensor can comprise a Galvanic Skin Response (GSR) sensor configured to detect changes in the resistance of skin to electrical current due to changes in skin perspiration. Measuring the change in skin perspiration can be designed to detect various physiological and/or psychological conditions. In addition or alternatively, one or more Electrocardiogram (ECG) sensors may be provided to monitor the condition of the heart muscle in a user. In still further examples, the sensors may be designed to detect features of the skin (e.g., temperature, glucose levels, levels of chemicals, pharmaceuticals, etc.). As such, the wireless sensor patch may have a wide range of applications. The wireless skin patch of the present subject matter can allow for comfortable application and monitoring without necessarily requiring a continuous wired connection. Moreover, the wireless sensor patch can be inexpensively produced, thereby rendering the patch potentially disposable. In disposable applications, a new wireless sensor patch is provided for each application; thereby avoiding expensive sanitation and cleaning procedures.

[0021] The wireless sensor patch 10 may include a memory device configured to store data collected by the sensor device. In addition or alternatively, the wireless sensor patch 10 may include a transmitter configured to transmit wireless signals 20 (e.g., by way of Bluetooth wireless technology) to be received by a device 30. The device 30 may be a cell phone or other receiving device that may in turn relay the information by satellite to another location for processing. In further examples, the wireless sensor patch may include a USB port or other interface to allow periodic wired connections with the wireless sensor patch. In such examples, after a period of time, the user may temporarily provide a wired connection between the patch and the device 30 (e.g., by a USB cable) to provide communication between the device and the wireless sensor patch. In such a manner, information may be gathered by the device 30 continuously (e.g., by a wireless connection) in real time synchronized with the device 30 and/or may be periodically sent to the device 30 when the user makes a wired or other direct connection between the device 30 and the wireless patch 10. Such wired or wireless connections can be used to download information from the wireless sensor patch 10 to the device 30 such as information gathered from the user and/or current information about the wireless sensor patch 10. In further examples, the wired or wireless connection may allow information or commands to be uploaded from the device 30 to the wireless sensor patch 10. For example, commands may be uploaded to change an operating condition of the patch, to provide information to be displayed by the patch, and/or other functionality.

[0022] In further examples, the device 30 may comprise a storage unit configured to store data being transmitted by the wireless sensor patch 10. In further examples, the device 30 may comprise a processing unit configured to process the data. In still further examples, the device 30 may optionally transmit signals 40 configured to be received by the wireless sensor patch 10. For example, the device 30 may send command signals to the wireless sensor patch 10 to change an operating condition of the wireless sensor patch 10.

[0023] Figure 2 is a top view of the representative wireless sensor patch 10 shown in Figure 1. The wireless sensor patch 10 includes a flexible support patch 50. As shown in Figure 3, the flexible support patch 50 includes a thickness defined between a first face 52 and a second face 54. As shown in Figures 2 and 4, the flexible support patch 50 includes an outer periphery 56 defining a footprint of the flexible support patch 50. The outer periphery 56 can comprise a wide range of shapes and sizes configured to be appropriately attached to the skin surface 12 of the user 1. The flexible support patch 50 can comprise a wide range of materials configured to provide support while still providing flexibility to allow the wireless sensor patch 10 to conform to a wide range of skin surface shapes. For example, the flexible support patch 50 can comprise a fabric represented by the cross-hatch pattern illustrated in the drawings. The illustrated fabric comprises a nonwoven fabric although woven fabrics may be provided in further examples.

[0024] The wireless sensor patch 10 may also include an adhesive layer 60 applied to the first face 52 of the flexible support patch 50. The adhesive layer can comprise a pressure sensitive adhesive such as a rubber-based adhesive, an acrylic adhesive or silicone adhesive that allows the patch to immediately adhere to the skin surface 12 upon application of the wireless sensor patch 10. Moreover, the wireless sensor patch 10 can optionally comprise one or more skin-friendly adhesive patch(es) 70 such as the illustrated first and second skin-friendly adhesive patch portions 70a, 70b mounted to the first face 52 of the flexible support patch 50 with the adhesive layer 60. In one example, the skin-friendly adhesive patch 70 can comprise a hydrocolloid adhesive patch although other skin- friendly adhesives may be provided such as an integrated hydrocolloid or other adhesives capable of absorbing moisture. For example, the skin-friendly adhesive patch 70 can comprise a hydrocolloid such as the hydrocolloid material disclosed in any one of U.S. Patent No. 7,335,416 that issued on February 6, 2008, U.S. Patent No. 6,710,100 that issued on March 23, 2004, U.S. Patent No. 6,583,220 that issued on June 24, 2003, U.S. Patent No. 6,326,421 that issued on December 4, 2001, U.S. Patent Application No. 12/866,750 filed August 9, 2010, and U.S. Provisional Patent 61/467,553 filed March 25, 2011, which are herein incorporated by reference in their entireties.

[0025] As shown in Figure 4, an outer periphery of the adhesive layer 60 can circumscribe the skin-friendly adhesive patch 70. As such, an outer peripheral adherence of the wireless sensor patch 10 to the skin surface 12 of the user 1 may be achieved. At the same time, the skin-friendly adhesive patch 70 may be held in place against the skin surface 12 to allow sufficient time for the skin-friendly adhesive patch 70 to cure into an effective adhesive member. The skin-friendly adhesive patch 70 allows the wireless sensor patch 10 to be applied to the skin surface for a significant length of time without aggravating the skin surface when compared to the adhesive layer 60. At the same time, a relatively small peripheral portion of the adhesive layer 60 may allow the peripheral portions of the patch to be immediately adhered to the skin surface while allowing the skin-friendly adhesive patch 70 sufficient time to cure.

[0026] Figure 5 illustrates an exploded view of the wireless sensor patch 10. Figure 6 is a cross-sectional view of the flexible support patch 50 demonstrating the adhesive layer 60 disposed on the first face 52 of the flexible support patch 50. Figure 7 is a cross-sectional view of the skin-friendly adhesive patch 70 along line 7-7 of Figure 5. As shown, the skin-friendly adhesive patch 70 can include a flexible substrate 71 with a skin-friendly adhesive layer 78 disposed on a first face 72 of the flexible substrate 71. In some examples, the flexible substrate 71 can comprise a transparent or translucent material to allow viewing of indicia 80 that may be printed on the second face 76 of the flexible substrate (e.g., see Figures 4 and 5). In such examples, the indicia 80 may be printed in reverse such that the information may be read by viewing the indicia through the skin-friendly adhesive layer 78 and the flexible substrate 71. The skin-friendly adhesive layer 78 can comprise a hydrocolloid adhesive or other skin-friendly adhesive that can facilitate adhesion to the skin surface for long periods of time without aggravating a user's skin.

[0027] As further illustrated in Figure 5, the wireless sensor patch 10 further includes a sensor device 90. Figure 5 illustrates a top perspective view of one example of the sensor device 90 while Figure 8 illustrates a bottom perspective view of the sensor device 90 along line 8-8 of Figure 5. As shown in Figure 8, the sensor device 90 can include a pair of Galvanic Skin Response (GSR) sensor probes 92a, 92b configured to interact with the skin surface 12 to detect changes in the resistance of skin to electrical current due to changes in skin perspiration. The sensor device 90 can also include a pair of Electrocardiogram (ECG) sensor probes 93a, 93b configured to monitor the condition of the heart muscle in a user.

[0028] An electronics module 100 may be provided that can receive signals from the pair of GSR sensor probes 92a, 92b and/or the pair of ECG sensor probes 93a, 93b. In some examples, the wireless sensor patch 10 may only be configured to operate with one of the sensor types although both sensor types may be configured to operate in further examples. For instance, as shown in Figure 4, only the GSR sensor probes 92a, 92b extend through the flexible support patch 50 to engage the skin surface of the user. The ECG sensor probes 93a, 93b are not exposed to interact with the skin surface and/or the electronics within the electronic module 100 may be arranged to turn off the ECG sensor and/or may not have ECG sensor functionality. Figure 5 demonstrates an example where apertures 55a, 55b are provided in the flexible support patch 50 in addition to a central aperture 57 to allow communication of the GSR sensor probes 92a, 92b and the ECG sensor probes 93a, 93b through the flexible support patch 50.

[0029] As further shown in Figure 8, the sensor device 90 can also include identification indicia 97 such as a UPC code or the like to refer to the specific sensor device 90 or a type of sensor device. Referring back to Figure 5, the sensor device 90 can also include a battery 99 configured to power the sensor device 90 and a control button 98 configured to operate the sensor device. The sensor device 90 can be mounted to the second face 54 of the flexible support patch 50 such that at least one of the sensor probes is aligned with the apertures. Indeed, as shown, the GSR sensor probes 92a, 92b are aligned with the central aperture 57 extending through the flexible support patch. Such alignment allows a portion of the GSR sensor probes 92a, 92b to protrude from the central aperture 57 as shown in Figure 3. Moreover, as shown in Figure 5, the ECG sensor probes 93a, 93b may be aligned with the corresponding apertures 55a, 55b extending through the flexible support patch 50. Although not shown, a hydrogel or conductive agent may also be provided to promote coupling of the ECG sensor probes 93a, 93b with the skin surface 12 through the corresponding apertures 55a, 55b.

[0030] The sensor device 90 may be mounted to the second face 54 of the flexible support patch 50 with various adhesive configurations. For instance, as shown in Figure 5, adhesive in the form of a tie layer patch 110 can be provided to affix the sensor device 90 to the second face 54 of the flexible support patch 50. As shown, apertures 113a, 113b may be provided in alignment with the ECG sensor probes 93a, 93b to facilitate appropriate interaction with the skin surface 12. Likewise, apertures 115a, 115b may be provided in alignment with the GSR sensor probes 92a, 92b to facilitate appropriate interaction with the skin surface 12. In some examples, the tie layer 110 may be transparent and/or translucent to allow viewing of the identification indicia 97 from below as shown in Figure 4.

[0031] The wireless sensor patch 10 further includes a flexible cover patch 120 affixed to the second face 54 of the flexible support patch 50 wherein the sensor device 90 is at least partially housed within a pocket 122 defined by at least one of the flexible support patch 50 and the flexible cover patch 120. For example, a protruding portion of the electronic module 100 can be housed within a preformed pocket 122 of the flexible cover patch 120. In many embodiments, the cover patch 120 generally overlies the sensor device 90. In some embodiments, the control button 98 may be activated by depressing a side portion of the flexible preformed pocket 122. The flexible cover patch may comprise a polymeric member, such as a closed cell foam material that may be substantially water resistant to protect the electrical components of the electronic module 100. As shown, the tie layer patch 110 may function to mount the flexible cover patch 120 to the second face 54 of the flexible support patch 50.

[0032] As further illustrated in Figure 2, the flexible cover patch 120 includes an outer periphery 124 defining a footprint of the flexible cover patch 120. As shown, in one example, the footprint of the flexible support patch 50 defined by an outer periphery 56 of the flexible support patch 50 is larger than a footprint of the flexible cover patch 120. Alternatively, providing the flexible cover patch 120 with a larger footprint can help prevent overlapping of the periphery 124 of the flexible cover patch 120 that may provide a peeling point. As such, the wireless sensor patch 10 can be securely applied to the skin surface 12 with a reduced potential of inadvertent peeling of the wireless sensor patch 10 from the skin surface 12.

[0033] Referring to Figures 3 and 5, a release liner 130 may be provided to help preserve the adhesive layer 60 and the skin-friendly adhesive layer 78 from adhering to other surfaces and/or contamination prior to application of the wireless sensor patch. [0034] The wireless sensor patch 10 shown in the referenced figures may be easily applied to the skin surface 12 of a user 1. As shown in Figures 3 and 5, the release liner 130 may be initially removed to expose the adhesive layer 60 and the skin-friendly adhesive layer 70, 78 as shown in Figure 4. Moreover, as shown in Figure 4, the indicia 80 may be read through the skin-friendly adhesive. Moreover, the indicia 97 associated with the sensor device 90 may be read through the tie layer patch 110. Next, the wireless sensor patch 10 may be applied to the skin surface 12 of a user 1 at an appropriate location. Once applied, the outer peripheral portion of the adhesive layer 60 immediately adheres the wireless sensor patch 10 in place, wherein, after sufficient time, the skin-friendly adhesive layer 70 cures to provide the primary bonding while reducing irritation and/or aggravation to the skin layer that may otherwise occur over long periods of time with only the adhesive layer 60.

[0035] In particular embodiments, the present subject matter utilizes a double adhesive coated, high tack, isoprene based adhesive layer for the tie layer patch 110. Specifically, referring to Figures 5 and 9, the tie layer patch 110 is disposed between (i) the sensor device 90 and/or the electronics module 100 and (ii) the flexible support patch 50. The tie layer patch 110 includes a substrate 112 having a first adhesive layer 111 disposed on a face of the substrate 112 and a second adhesive layer 114 disposed on an oppositely directed face of the substrate 112. The first adhesive layer 111 includes at least one isoprene based adhesive. The outer face 116 of the first adhesive 111 contacts and adheres to the sensor device 90 and/or the electronics module 100. The outer face 117 of the second adhesive 114 contacts and adheres to the flexible support patch 50 and particularly the face 54 of the patch 50.

[0036] In many embodiments, the first adhesive of layer 111 includes a styrene isoprene styrene (SIS) adhesive, a styrene isoprene (SI) adhesive, or a combination or blend thereof. An example of a suitable adhesive for use in layer 111 is T2200 adhesive which is commercially available from Avery Dennison Corporation. In addition to, or instead of, SIS and/or SI adhesives; the first adhesive layer can also include one or more of the following isoprene-based materials: bromo isobutylene isoprene, chloro isobutylene isoprene, polyisoprene, isobutylene isoprene butyl, and combinations thereof.

[0037] The first adhesive used in layer 111 may additionally comprise one or more tackifiers. Representative, nonlimiting examples of such tackifiers include hydrocarbon resins and rosin resins. Such tackifiers include, but are not limited to, rosins and rosin derivatives including rosinous materials that occur naturally in the oleoresin of pine trees, as well as derivatives thereof including rosin esters, modified rosins such as fractionated, hydrogenated, dehydrogenated, and polymerized rosins, modified rosin esters and the like. Generally, up to about 45 parts tackifier per hundred parts polymer are added. However, it will be appreciated that the present subject matter includes the use of lesser amounts and/or greater amounts of tackifiers.

[0038] A wide range of tackifiers are commercially available including, but not limited to, Foral^® 85 (glycerol ester of a highly stabilized rosin), Foral^® 105 (pentaerythritol ester of a hydrogenated rosin), Stabilite ester 10, and Pentalyn^® H, manufactured and sold by Hercules, inc.. PE Estergum and the like, manufactured by Arizona Chemical Co., and Sylvatac^® 40N, Sylvatac^® RX, Sylvatac^® 95 and the like, manufactured by Sylvachem Corporation.

[0039] There may also be employed as tackifiers terpene resins which are hydrocarbons of the formula C10H16, occurring in most essential oils and oleoresins of plants, and phenol modified terpene resins like alpha pinene, beta pinene, dipentene, limonene, myrecene, bornylene, camphene, and the like. Various aliphatic hydrocarbon resins like Escorez™ 1304, manufactured by Exxon Chemical Co., and aromatic hydrocarbon resins based on C9's, C5's, dicyclopentadiene, coumarone, indene, styrene, substituted styrenes and styrene derivatives and the like can also be used.

[0040] Hydrogenated and partially hydrogenated resins such as Regalrez™ 1018, Regalrez™ 1033, Regalrez™ 1078, Regalrez™ 1094, Regalrez™ 1126, Regalrez™ 3102, Regalrez™ 6108, etc., produced by Hercules Corporation, can be used as tackifiers in the present subject matter as well. Various terpene phenolic resins of the type SP 560, manufactured and sold by Schenectady Chemical Inc., Nirez 1100, manufactured and sold by Reichoid Chemical Inc., and Piccolyte^® S-100, manufactured and sold by Hercules Corporation, are particularly useful tackifiers for the present subject matter. Further, various mixed aliphatic and aromatic resins, such as Hercotex AD 1100, manufactured and sold by Hercules Corporation, can also be used as tackifiers.

[0041] In particular embodiments, the adhesives include Escorez™ 5400 series tackifiers from Exxon, and/or the Eastotac™ and/or Piccotac™ tackifiers available from Eastman.

[0042] The first adhesive forming the layer 111 of the tie layer 110 is typically applied at a coat weight within a range of from about 50 gsm to about 75 gsm, with 45 gsm being useful for many applications.

[0043] In many embodiments, the second adhesive of layer 114 of the tie layer 110 depicted in Figure 9 includes a styrene isoprene styrene (SIS) hot melt rubber adhesive, a styrene butadiene styrene (SBS) adhesive, or combinations thereof. It is contemplated that nearly any pressure sensitive adhesive including a rubber-based pressure sensitive adhesive and/or a non-rubber-based pressure sensitive adhesive could be used for the second adhesive of layer 114. A nonlimiting example of a non-rubber-based adhesive is a noncrosslinked acrylic adhesive. Examples of suitable adhesives for use in layer 114 include T2200, T2701, and/or T407 which are all commercially available from Avery Dennison Corporation.

[0044] The second adhesive forming the layer 114 is typically applied at a coat weight within a range of from about 40 gsm to about 75 gsm, with 45 gsm being useful for many applications.

[0045] The substrate 112 of the tie layer 110 is typically a polymeric film such as polyethylene, polypropylene, or polyethylene terephthalate (PET). Combinations of these can be used. However, it will be appreciated that the substrate 112 can include a variety of other materials and potentially in combination with the noted films. [0046] Generally, the substrate 112 should be relatively thin however, sufficiently thick to provide support strength in the resulting assembly. Typically, the substrate 112 has a thickness within a range of from about 12 microns to about 15 microns. However, the present subject matter includes the use of other thicknesses for the substrate 112.

[0047] The present subject matter also provides methods of forming wireless sensor patches as described herein. The methods include one or more operations of sealing the sensor device between cover components such as the flexible cover patch and one or both of the flexible support patch and adhesive tie layer. As previously described, the adhesive tie layer is typically positioned between the sensor device and the flexible support patch. The sealing operations include either heating the isoprene based adhesive of the tie layer and/or subjecting the isoprene based adhesive such that the adhesive flows and seals, i.e., fills, any voids or gaps in the resulting assembly, thereby rendering the assembly resistant to water ingress.

[0048] In particular embodiments, the sealing operation(s) involve heating the adhesive tie layer and specifically, the isoprene based adhesive to a temperature of at least about 150° C, more particularly to 205° C, and in certain versions up to 315° C.

[0049] The sealing operation(s) may also involve subjecting the adhesive tie layer and specifically, the isoprene based adhesive to a pressure of at least about 1.5 kg, more particularly to about 2.75 kg, and in certain versions up to about 4 kg per cm² of surface area of the adhesive.

[0050] The sealing operation(s) can also include combinations of heating and pressurizing.

[0051] The time periods of heating and/or pressurizing are generally those which are sufficient to allow the isoprene based adhesive to flow and thereby seal. These time periods may vary depending upon manufacturing and process parameters. However, such time periods are typically within a range of from about 0.1 seconds to about 15 seconds. It will be understood that the present subject matter includes the use of time periods less than 0.1 seconds and longer than 15 seconds. [0052] The present subject matter provides several benefits. During batch mixing of the adhesive(s) used in the tie layer, i.e., layer 110, there is a risk of the adhesive being exposed to high temperatures for an extended time period. For example, this may occur while the adhesive is waiting to be coated while a previous batch is being run, thereby resulting in thermal degradation. As previously noted, for SBS based hot melt adhesives, thermal degradation creates chemical crosslinks, which will reduce the adhesive's ability to flow. While the adhesive can still be coated, its ability to reduce water ingress channels with a post treatment (heat and/or pressure) after patch assembly may be ineffective. This is not the case with many isoprene based adhesives and particularly SIS based hot melt adhesives, which will undergo chain scission and therefore, improve their ability to flow.

[0053] In addition, during a post treatment with heat and pressure, the adhesive is exposed to heat and excessive heat can reduce the flow of the adhesive, thereby making the treatment less effective. This is not the case with SIS based hotmelt adhesives.

[0054] Many other benefits will no doubt become apparent from future application and development of this technology.

[0055] All patents, applications, standards, and articles noted herein are hereby incorporated by reference in their entirety.

[0056] The present subject matter includes all operable combinations of features and aspects described herein. Thus, for example if one feature is described in association with an embodiment and another feature is described in association with another embodiment, it will be understood that the present subject matter includes embodiments having a combination of these features.

[0057] As described hereinabove, the present subject matter solves many problems associated with previous strategies, systems and/or devices. However, it will be appreciated that various changes in the details, materials and arrangements of components, which have been herein described and illustrated in order to explain the nature of the present subject matter, may be made by those skilled in the art without departing from the principle and scope of the claimed subject matter, as expressed in the appended claims.

Claims

Claims What is claimed is:

1. A wireless sensor patch for adhesive attachment to a user's skin, the sensor patch comprising:

a sensor device including electronics and at least one sensor for detecting a physiological state of a user;

a flexible cover patch overlying the sensor device;

a flexible support patch, the support patch defining a first face directed toward the sensor device and an oppositely directed second face, wherein the support patch and the cover patch generally enclose the sensor device;

a skin-friendly adhesive disposed on the second face of the flexible support patch;

an adhesive tie layer patch disposed between the sensor device and the support patch, wherein the adhesive tie layer includes at least one isoprene based adhesive.

2. The sensor patch of claim 1 wherein the isoprene based adhesive is selected from the group consisting of a styrene isoprene styrene (SIS) adhesive, a styrene isoprene (SI) adhesive, and combinations thereof.

3. The sensor patch of either of claims 1 or 2 wherein the isoprene based adhesive further includes a tackifier.

4. The sensor patch of any one of claims 1-3 wherein the isoprene based adhesive has a coat weight within a range of from 50 gsm to 75 gsm.

5. The sensor patch of any one of claims 1-4 wherein the adhesive tie layer patch includes a substrate upon which the isoprene based adhesive is disposed.

6. The sensor patch of claim 5 wherein the substrate is selected from polyethylene, polypropylene, polyethylene terephthalate, and combinations thereof.

7. The sensor patch of either of claims 5 or 6 wherein the substrate has a thickness within a range of from 12 microns to 15 microns.

8. The sensor patch of any one of claims 1-4 wherein the adhesive tie layer patch includes another adhesive on a face that is oppositely directed from the isoprene based adhesive.

9. The sensor patch of claim 8 wherein the other adhesive of the tie layer patch is selected from the group consisting of a styrene isoprene styrene (SIS) adhesive, a styrene butadiene styrene (SBS) adhesive, and combinations thereof.

10. The sensor patch of either of claims 8 or 9 wherein the other adhesive has a coat weight within a range of from 40 gsm to 75 gsm.

11. The sensor patch of any one of claims 1-10 wherein the adhesive tie patch is in the form of a double coated isoprene based adhesive tape.

12. The sensor patch of claim 1 wherein the isoprene based adhesive is a pressure sensitive adhesive.

13. A method of forming a wireless sensor patch that is resistant to water ingress, the method comprising:

providing (i) a sensor device including electronics and at least one sensor for detecting a physiological state of a user, (ii) a flexible cover patch, (iii) a flexible support patch, and (iv) an adhesive tie layer patch that includes at least one isoprene based adhesive;

sealing the sensor device between the flexible cover patch and at least one of the flexible support patch and the adhesive tie layer.

14. The method of claim 13 wherein the sealing includes subjecting the isoprene based adhesive to a temperature or a pressure at which the adhesive flows.

15. The method of either of claims 13 or 14 wherein the sealing includes heating the isoprene based adhesive to a temperature of at least 150° C.

16. The method of any one of claims 13-15 wherein the sealing includes subjecting the isoprene based adhesive to a pressure of at least 1.5 kg per cm².

17. The method of either of claims 13 or 14 wherein the sealing includes heating the isoprene based adhesive to a temperature of at least 150° C and subjecting the isoprene based adhesive to a pressure of at least 1.5 kg per cm², for a time period within a range of from 0.1 seconds to 15 seconds.

18. The wireless sensor patch produced by any of the methods of claims 13-17.