FUNCTIONAL FABRIC DEVICES HAVING INTEGRATED SENSORS
20210077304 ยท 2021-03-18
Inventors
Cpc classification
A61F5/01
HUMAN NECESSITIES
A61B5/053
HUMAN NECESSITIES
A61B5/445
HUMAN NECESSITIES
A61B5/7214
HUMAN NECESSITIES
A61B5/447
HUMAN NECESSITIES
A61B2560/0223
HUMAN NECESSITIES
A61B5/022
HUMAN NECESSITIES
A61B2560/0242
HUMAN NECESSITIES
A61B5/002
HUMAN NECESSITIES
A61B2562/0219
HUMAN NECESSITIES
A61B5/01
HUMAN NECESSITIES
International classification
A61B5/00
HUMAN NECESSITIES
A61B5/022
HUMAN NECESSITIES
A61B5/11
HUMAN NECESSITIES
Abstract
Provided herein are smart functional fabrics and therapeutic/diagnostic garments which utilize flexible wireless electronic devices to enhance functionality, for example, by measuring key therapy parameters and providing data to clinicians, and methods utilizing such devices. The provided methods are designed to avoid patient discomfort and decrease harm or irritation caused by garments which utilize bulkier, more rigid sensors. Additionally, the described devices are multiplexed to allow for sensing of multiple parameters of therapeutic interest and combinations of measured data for new clinical metrics.
Claims
1-3. (canceled)
4. A system comprising: a functional fabric; at least one flexible, wireless device comprising: a pressure sensor for measuring one or more pressures exerted by said functional fabric on a region of a body of a subject contacted with said functional fabric system; a wireless communication system; and wherein said at least one flexible device is positioned in mechanical communication with a surface of said functional fabric; wherein said flexible wireless device has dimensions and physical properties such that the pressure sensor affects the magnitude of said one or more pressures exerted by said functional fabric by less than or equal to a factor of 25%.
5. (canceled)
6. (canceled)
7. The system of claim 4, wherein said functional fabric is a therapeutic or diagnostic garment.
8. The system of claim 4, wherein said functional fabric is a compression garment.
9. The system of claim 4, wherein said functional fabric comprises one or more of an inelastic material, an elastic material, a woven material, a non-woven material, an adhesive, and a knit material.
10. The system of claim 4, wherein said functional fabric is moistened, heated or cooled.
11. The system of claim 4 wherein said functional fabric is a stocking, sock, sleeve, glove, wrap, bandage, hard cast, soft cast, splint or a pneumatic compression device.
12. The system of claim 4, wherein said functional fabric is a therapeutic compression stocking or bandage.
13. The system of claim 4, wherein said at least one flexible wireless device is affixed to said functional fabric.
14. The system of claim 4, wherein said at least one flexible wireless device is affixed to said functional fabric via an adhesive.
15. The system of claim 4, wherein said at least one flexible wireless device is directly or indirectly supported by a region of a body of a subject contacted with said system.
16. The system of claim 4, wherein said at least one flexible wireless device is configured to be supported by the skin of a subject contacted with said system or supported by a fabric or other layer provided on the skin of a subject contacted with said system or supported.
17. The system of claim 4, wherein said at least one flexible wireless device is characterized by an average Young's modulus less than or equal to less than or equal to 1 MPa.
18. The system of claim 4, wherein said at least one flexible wireless device is characterized by an average Young's modulus matched to within a factor of 100 of the Young's modulus of the skin of a subject.
19. The system of claim 4, wherein said at least one flexible wireless device has a net bending stiffness low enough that the device establishes conformal contact with the skin of the subject.
20. The system of claim 4, wherein said at least one flexible wireless device has a net bending stiffness less than or equal to 1 nN m.
21. The system of claim 4, wherein said at least one flexible wireless device has net flexural rigidity of less than or equal to 110.sup.4 Nm.
22. The system of claim 4, wherein said at least one flexible wireless device further comprises: a flexible substrate; a flexible electronic circuit supported by the flexible substrate, wherein the flexible electronic circuit comprises said pressure sensor and said wireless communication system; and a flexible superstrate layer encapsulating at least a portion of the flexible electronic circuit, the flexible substrate, or both the flexible electronic circuit and the flexible substrate.
23. The system of claim 22, wherein said flexible substrate and said flexible superstrate layer independently are characterized by an average modulus less than or equal to 1 MPa.
24. The system of claim 4, wherein said at least one flexible wireless device is a stretchable device.
25. The system of claim 24, wherein said stretchable device is capable of undergoing elongation or compression to an extent of at least a factor of 1.2 without system degradation or mechanical failure.
26. The system of claim 25, wherein said flexible wireless device of said stretchable device further comprises one or more stretchable filamentary electrical interconnects.
27. The system of claim 26, wherein said stretchable filamentary electrical interconnects have a serpentine, bent, folded, wavy or curved geometry.
28. The system of claim 4, wherein said pressure sensor is a capacitance pressure sensor, a piezoresistive pressure sensor or a combination thereof.
29. The system of claim 4, wherein said pressure sensor measures instantaneous pressure, average pressure, cumulative pressure or any combination of these.
30. The system of claim 4, wherein said pressure sensor measures the inherent extensibility of the functional fabric.
31. The system of claim 4, wherein said flexible wireless device is capable of determining the static stiffness index of the functional fabric.
32. The system of claim 4, wherein said at least one flexible wireless device further comprises one or more sensors selected from the group consisting of: a temperature sensor; a bioimpedence sensor; a radius of curvature sensor, an accelerometer, a heart rate sensor, a blood flow sensor, an electrocardiography sensor, an electromyography sensor, an electroencephalography sensor, an electrophysiological sensors, a moisture sensor, a humidity sensor, a transcutaneous oxygen sensor, a local blood flow sensor, and a local redness sensor.
33. The system of claim 4, wherein said at least one flexible wireless device further comprises a temperature sensor for measuring local temperature.
34. The system of claim 33, wherein said flexible wireless device uses said local temperature to provide a pressure measurement normalized by an in situ temperature.
35. The system of claim 4, wherein said at least one flexible wireless device further comprises an accelerometer for monitoring the motion or movement of a subject or detecting a fall of the subject.
36. The system of claim 4, wherein said at least one flexible wireless device further comprises a wound healing sensor.
37. The system of claim 36, wherein said wound healing sensor is for monitoring transcutaneous oxygen, local blood flow, local redness, local temperature, ultraviolet radiation, or any combination of them.
38. The system of claim 4, wherein said at least one flexible wireless device further comprises a light emitting diode.
39. The system of claim 38, wherein said light emitting diode is activated when said pressure sensor senses a pressure below a minimum compression threshold.
40-48. (canceled)
49. The system of claim 4, further comprising at least three wireless flexible devices.
50. The system of claim 49, wherein each of said wireless flexible devices independently comprise a sensor and a near-field communication system.
51. The system of claim 50, wherein said wireless flexible devices are positioned within said functional fabric such that when the covering is worn by a patient the wireless flexible devices contact said patient's gastrocnemius muscle, medial ankle and upper anterolateral thigh.
52. The system of claim 4, wherein said at least one flexible wireless device has an average thickness of less than or equal to 10 mm.
53. The system of claim 4, wherein said at least one flexible wireless device has an average thickness of less than or equal to 5 mm.
54. The system of claim 4, wherein said at least one flexible wireless device has a lateral area footprint less than or equal to 20,000 mm.sup.2.
55. The system of claim 4, wherein said system further comprises one or more encapsulating layers.
56. The system of claim 55, wherein said flexible wireless device is entirely encapsulated by said one or more encapsulating layers.
57. The system of claim 55, wherein each of said encapsulating layers independently have a thickness less than or equal to 5 mm.
58. The system of claim 55, wherein said one or more encapsulating layers independently have a geometry without hard edges or concerns that provides for good adherence to the skin and reduced contact stresses.
59. The system of claim 55, wherein said one or more encapsulating layers independently have a geometry characterized by one or more curved surfaces.
60. The system of claim 55, wherein said one or more encapsulating layers independently have a dome shaped geometry.
61. The system of claim 60, wherein said dome shaped geometry is characterized by a fillet radius greater than or equal to 0.25 mm.
62. The system of claim 55, wherein said pressure sensor of said flexible wireless device is encapsulated by a lower encapsulating layer and an upper encapsulating layer.
63. The system of claim 62, wherein said pressure sensor is a piezoelectric sensor, capacitive sensor, a liquid metal sensor, a strain gauge sensor or an iontronic sensor.
64. The system of claim 62, wherein said an upper encapsulating layer has a thickness at least 1.5 times greater than a thickness of the lower encapsulating layer.
65. The system of claim 62, wherein said an upper encapsulating layer has a length at least 1.5 times less than a length of the lower encapsulating layer.
66. The system of claim 62, wherein said lower encapsulating layer has a geometry characterized by a thickness at least 8 times smaller than at least one lateral dimension.
67. The system of claim 62, wherein said lower encapsulating layer has a geometry characterized by a thickness at least 8 times smaller than a width of said lower encapsulating layer.
68. The system of claim 55, wherein said one or more encapsulating layer is polyimide, polydimethylsiloxane (PDMS), polyurethane, polystyrene, polymethyl methacrylate (PMMA) or polycarbonate.
69. The system of claim 4, wherein said wireless communication system is selected from the group consisting of: a transmitter, a receiver, a transceiver, an antenna, and a near field communication device.
70. The system of claim 4, wherein said wireless communication system is one or more near field coils.
71. The system of claim 70, wherein said one or more near field coils independently have a diameter selected from the range of 500 microns to 20 millimeters.
72. The system of claim 70, wherein said one or more near field coils independently has an average thickness selected from the range of 1 micron to 5 millimeters.
73. The system of claim 70, wherein said one or more near field coils independently has a geometry selected from the group consisting of: an annulus and an elliptical annulus.
74. The system of claim 4, wherein said wireless communication system provides Bluetooth wireless communication.
75. The system of claim 4, wherein said wireless communication system provides one-way or two-way wireless communication with an external device.
76. The system of claim 75, wherein said external device is a computer, a phone, a smartphone, a tablet or a diagnostic machine.
77. The system of claim 4, wherein said flexible wireless device further comprises a wireless energy harvester.
78. The system of claim 77, wherein said wireless energy harvester has an area antenna.
79. The system of claim 78, wherein said area antenna has a length that is greater than or equal to 100 cm.
80. The system of claim 77, wherein said wireless energy harvester provides a power delivery of greater than or equal to 110.sup.4 mW/cm.sup.2.
81. The system of claim 4, wherein said flexible wireless device further comprises one or more battery.
82. The system of claim 4, wherein said flexible wireless device does not include a battery.
83. The system of claim 4, wherein said system further comprises a processor to provide a real-time metric.
84. The system of claim 83, wherein said processor is on-board with the flexible wireless device or is positioned in an external device that is located at a distance from the wireless device and in wireless communication with the wireless communication system.
85. The system of claim 4, wherein said flexible wireless device continuously monitors and generates a real-time metric.
86. The system of claim 4, wherein said flexible wireless device further comprises one or more of a vibratory motor, an electrode, a light emitter, or a thermal actuator.
87. The system of claim 4, comprising a plurality of spatially distributed flexible wireless devices.
88. The system of claim 87, wherein the plurality of spatially distributed flexible wireless devices are configured to provide an average output parameter and/or a spatial distribution map of an output parameter.
89. The system of claim 88, wherein said output parameter and/or spatial distribution map is time-varying.
90. The system of claim 87, that is a multiplexed system configured to provide an output for a plurality of output parameters.
91. The system of claim 87 configured to wirelessly communicate output parameters from the system for remote monitoring.
92. The system of claim 87, further comprising one or more actuators connected to the garment, wherein the actuators are configured to receive an input from a user, a medical professional or a feedback input based on one or more sensor outputs from one or more of the sensors.
93. A method of measuring an interface pressure of said functional fabric on a region of a body of a subject using the systems of claim 4.
94. The method of claim 93 wherein said interface pressure is an instantaneous pressure, an average pressure or a cumulative pressure.
95. A method of measuring a pressure and a limb volume upon administration of the functional fabric on a region of a body of a subject using the systems of claim 4.
96. A method of determining a limb volume response upon administration of the functional fabric on a region of a body of a subject using the systems of claim 4.
97. A method of treating edema, venous status ulcers, chronic venous insufficiency, deep vein thrombosis, lipodermatosclerosis, lymphedema or any combination of these using the systems of claim 4.
98. A method of assessing fabric failure of said functional fabric using said system of claim 4.
99. A method of monitoring patient adherence of said functional fabric using said system of claim 4.
100. A method of providing compression therapy to a subject comprising: providing a system of claim 4; and administering said system to a limb of the patent.
101. The method of claim 100, wherein said compression therapy is for treatment of venous status ulcers, chronic venous insufficiency, deep vein thrombosis, lipodermatosclerosis, lymphedema or a combination thereof.
102. The method of claim 100, wherein placement of said system in distinct anatomical locations provides an estimate of a global therapeutic pressure.
103-110. (canceled)
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE INVENTION
[0105] In general, the terms and phrases used herein have their art-recognized meaning, which can be found by reference to standard texts, journal references and contexts known to those skilled in the art. The following definitions are provided to clarify their specific use in the context of the invention.
[0106] Functional fabric refers to a substrate having an inner facing and outer facing surface, with the inner facing surface directed to a user's skin and the outer facing surface away from the skin, with a material thickness separating the surfaces. The term is used broadly herein, reflecting that the devices and methods described herein have a broad range of applications. For example, the functional fabric may be a textile or garment. The terms textile and garment may be used interchangeably with both a therapeutic garment and a diagnostic garment. Functional fabric may be, for example, a medical wrap, bandage, medical garment, a compression garment, an inelastic functional fabric, an elastic functional fabric, a woven functional fabric, a non-woven functional fabric or a knit functional fabric. Garment may be a sock, stocking, sleeve, glove, shirt, tights, skull cap, or other type of clothing. Garment may also refer to wraps, bandages, wound dressings, braces, hard casts, soft casts, splints, pneumatic compression devices and other medical devices. A functional fabric as described herein may be a therapeutic compression stocking. The functional fabric may be moistened, heated or cooled, including a precise manner and/or feedback-type loop, with one or more sensors providing an input used to drive one or more actuators to provide desired functionality. Functional fabric may also refer to performance or smart garments, for example, performance athletic wear with additional smart properties such as cooling, heating, aiding recovery or reducing muscle soreness (e.g. reducing lactic acid), preventing injury, sweat wicking, adding moisture, compression, antibacterial properties, polymer coatings and the like. The functional fabric may be capable of a therapeutic functionality, such as compression, would healing or reduction of muscle soreness. The functional fabric may have a diagnostic and/or monitoring function, such a monitoring or adjusting a physical or physiological parameter such as temperature, pressure, blood oxygen, UV exposure, limb volume and the like. Accordingly, the term functional in a functional fabric refers to a fabric having one or more sensors to provide useful and actionable information, with that information specific for an application of interest. For example, confirmation of pressure, length of time worn, an environmental parameter such as heat, light intensity, moisture, a skin-specific property such as oxygenation, blood flow, skin discoloration or redness.
[0107] Pressure sensor refers to a device capable of generating a signal corresponding to pressure generated between the compression covering and the tissue or skin of a wearer of the compression covering. Pressure sensors may include capacitive pressure sensor or peizoresistant sensors. In embodiments, pressure sensors have a thickness of less than or equal to 10 mm, less than or equal to 5 mm, less than or equal to 2.5 mm, or optionally, less than or equal to 1 mm. Pressure sensors, in some embodiments, may further measure circumferential leg pressure, for example, to estimate leg volume.
[0108] Communication system refers to components or systems which allow the device to send a signal to monitoring device, for example, a personal computer or smartphone. In embodiments, communication systems are selected from the group consisting of a transmitter, a receiver, a transceiver, an antenna, and a near field communication device. Communication system may include devices capable of Bluetooth communication.
[0109] Barrier layer and/or encapsulating layer refer to one or more layers configured to prevent moisture from reaching the electronic components, for example, the pressure sensor, the limb volume sensor and/or the near field communications chip. Encapsulating layers may surround a device or device component whereas barrier layers may protect one surface or side of a component. In embodiments, a substrate and a barrier layer may combine to form an encapsulating layer. In embodiments, encapsulating layers have a thickness less than or equal to 5 mm, less than or equal to 2.5 mm, or optionally, less than or equal to 1 mm.
[0110] Without substantial inflammation, irritation or discomfort refers to the capability of the present sensors to contact a skin or tissue surface without causing patient discomfort or skin irritation, for example, wounds, rash, scaling, inflammation and/or immune response. In some embodiments, for example, the sensor may have properties and dimensions such that a patent wearing a compression covering cannot feel the sensor, or the sensor impact is negligible. The term refers to at least there being no observable adverse impact to the tissue surface by the naked eye.
[0111] Real-time metric is used broadly herein to refer to any output that is useful in medical well-being. It may refer to or be derived from temperature, pressure, limb volume, skin contact, patient adherence, sweat analysis or any other patient parameter as described herein. Real-time metrics may be derived values such as temperature-pressure maps generated by a network of wireless devices positioned in contact with a patient under a therapeutic garment. Real-time metric may refer to a clinical metric, which provides a caregiver with additional insight into the health or healing of a patient. A real-time metric may also be referred herein generally as a parameter that is measured by a sensor, including a parameter relevant for a therapeutic assessment. Examples include, but are not limited to, one or more of: pressure, limb volume, tissue coloration (e.g., redness), temperature, force, stress, blood flow, oxygenation, position or location, strain, motion, elapsed time worn, total number of times garment put on and taken off. Any of the systems and methods may be described as multiplexed, including having a plurality of devices for measuring a plurality of parameters, including real-time metrics.
[0112] Conformal integration refers to the ability of the present systems to be provided to a tissue in a manner that the device spatially conforms at an interface between the system and the tissue or at the interface with an intermediate structure provided between the system and tissue surface. Conformal integration may be via direct or indirect contact with a tissue surface.
[0113] Spatially Distributed refers to positioning multiple flexible wireless devices such that they take measurements via sensors different positions on the skin, on a single limb or body part, or on multiple body parts. Spatial distribution may be designed to provide additional information to the user or caregiver my targeting specific regions, muscles, body parts or to provide error checking by comparing and contrasting each of the measurements. Spatially distributed may refer to distribution within a therapeutic garment, a patient or part of a patient, or a combination thereof.
[0114] Output parameter refers to a signal output of one or more physical properties or conditions measured by the flexible wireless devices as described herein. Output parameter may refer to temperature, pressure, limb volume, bioimpedence, patient adherence or any other property or condition as described herein. Output parameters may be calculated values or metrics, for example real-time metrics, using one or more additional output parameters or measurements to derive or combine measurements into more complex or informative parameters.
[0115] Spatial distribution map refers to combining a plurality of output parameters captured by a plurality of spatially distributed flexible wireless devices to generate a two or three dimensional map the output parameters.
[0116] Actuator refers to a component of a flexible wireless device that is capable of interacting with the user of the device, the therapeutic garment or the surrounding environment. For example, an actuator may be a vibratory motor, an electrode, a light emitter, a screen or a thermal actuator. Actuators may engage or interact based on an external signal, for example, from a user or caregiver. Actuators may be engaged via an electronic device (laptop, smartphone, etc.) in wireless communication with the flexible wireless device. Actuators may be useful in telemedicine style treatments for allowing a caregiver to remotely engage or disengage actuators as part of treatment or therapy.
[0117] Feedback input refers to a means of engaging or disengaging a component of the flexible wireless device (e.g. a signal or actuator) that is generated by a sensor or processor of the wireless device. For example, a pressure sensor may provide a feedback input to a LED when the pressure falls below therapeutic levels to alert the user or medical professional that the therapeutic garment should be replaced or repositioned.
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[0120] In order to generate clinical metrics, real-time metrics or spatial distribution maps the flexible wireless device 110 may include an on-board processor 310 or use wireless communication to provide a signal to an external processor, for example, a laptop 400 (as seen in
Example 1: Treatment of Venous Stasis Ulcers by Compression Therapy
[0121] More than 500,000 Americans suffer from venous stasis ulcers (VSUs), a condition driven by lower extremity venous hypertension, which costs the U.S. healthcare system more than $1 billion annually. The cornerstone of treatment involves the use of medical compression stockings that deliver therapeutic pressure to the lower extremities. In this example, the described therapeutic garment is a compression stocking. Compression stockings aid in venous return and promote wound healing. Recent meta-analyses and consensus statements from leading venous medicine societies have shown that compression stockings both speed healing for VSUs and prevent their recurrence. Furthermore, higher therapeutic pressures can be more effective in promoting VSU healing.
[0122] Garment manufacturers grade the strength of their products (e.g. 10-20 mmHg, 20-30 mmHg, 30-40 mmHg) based on tensile strength testing in vitro. Currently, there are no commercially available medical compression stockings that provide in vivo feedback of therapeutic pressure. Interface pressure measurements have been largely limited to research settings given their cost, bulkiness and unsuitability for continuous wear. Even though a garment may be rated the same strength, the actual therapeutic pressure varies with the patient's skin collapsibility, volume changes with body position, garment fit and patient adherence. Thus, there is a clinical need for a smart compression stocking device that is able to provide real-time feedback of interface pressure to ensure adequate therapeutic pressure and patient adherence.
[0123] Patients with VSUs have extremely delicate skin. Rigid and sharp electronic devices may pose risks to the patent, including infection. Large, bulky systems will also likely negatively impact patient adherence and comfort. The Rogers group has pioneered the development of flexible electronic systems that are mechanically invisible, highly stretchable, and wirelessly powered. These devices negate the need for rigid, brittle silicon electronic boards and allow for intimate skin connection. These flexible electronic sensors can be integrated with medical compression stockings and pair with smartphones for wireless data transmission and monitoring.
[0124] In embodiments, provided are pressure sensing systems and methods for adequate therapeutic compression with inelastic and elastic compression stockings of the legs and arms. The systems and methods may also assess patient adherence of their use of inelastic and elastic compression stockings. In embodiments, the systems and methods provide the ability to track the efficacy of oral medications (e.g. furosemide) used to reduce leg edema in other conditions such as heart failure and/or assess swelling in the setting of acute thrombosis of the lower legs. Further, some embodiments provide the ability to determine when a compression stocking has lost tensile strength reminding users/physicians to purchase a new device
[0125] Provided is a thin, flexible platform allows intimate connection with the skin that allows for continued use. Additionally, sensor design allows for unparalleled accuracy and repeatability of pressure that can be placed at anatomically important locations of the leg. Another advantage of the provided systems and methods is a lack of rigid electronics, which reduces risk of skin infection or inadvertent injury. The provided communications system (e.g. near-field communication, Bluetooth) enables wireless data transfer to standard smartphones. Some embodiments utilize temperature sensing, which is useful to determine patient adherence in regards to wearing compression garments and may be tracked by a patient's own smartphone or the device itself. In some embodiments, the smart compression stocking may allow for disposal when the compression provided by the garment is no longer of therapeutic value.
[0126] This example provides a compression stocking which incorporates a pressure sensor (capacitive or piezoresistive), integration of this pressure sensor within a flexible, electronic platform which further includes a communication system (e.g. a near-field communication chip). Some embodiments may also include a temperature sensor and/or an adhesive backing. The described garment may allow for integration with a smartphone enabling data download and off-line evaluation of continuous pressure data. This data can trigger text messages that allow users to increase compression as needed for therapeutic benefit.
[0127] In embodiments, LED integrated onto the flexible, electronic platform may provide notification of pressure thresholds enabling immediate user feedback when a level of pressure falls below therapeutic levels or reaches a pressure level that may increase the risk of ischemia.
[0128] Additionally, some embodiments sense leg volume (e.g. through the use of a bioimpedance measurements or strain gauges) allowing for the determination of the optimal balance between compression strength (interface pressure) and edema reduction (volume).
[0129] The provided pressure sensor serves as the basis of measurement. The pressure sensor is embedded within a flexible, electronic platform which may include an adhesive backing for integration with a therapeutic garment. The electronic platform includes thin wires organized in serpentine fashion to allow for skin deformations without loss of performance. A communication system is integrated within these wires and collects data longitudinally from the pressure sensor. In some embodiments, this negates the need for an onboard battery. The pressure sensor, or an additional sensor, may also be able to detect skin temperature, which can be used to assess whether a patient is using their compression garment.
[0130] In an embodiment, device is applied directly to the skin of the lower legs at key anatomical locations (overlying the gastrocnemius muscle, the medial ankle, and upper anterolateral thigh). The overlying compression stocking is applied over the sensor. Given the thinness of the device, the device will be mechanically invisible to the user. In additional embodiments, the flexible electronic device is integrated within the compression stocking, allowing for application to the skin simply by putting on the garment.
[0131] The sensor's data is then transferred onto a smartphone for data collection through the communication system. The data can be used to send text messages to inform the user to increase the tightness of fit of the compression garment in order to increase interface pressure. These triggers can be programmed by the physician.
[0132] The completed prototype will require no external wires or rigid circuit boards. The devices and systems described herein may be disposable. In an embodiment, the data from sensor will be stored on the communication system within the platform. The user will simply pair any smartphone to capture the data. As a test, pressure was applied using a standard sphygmomanometer, illustrating the differences in pressure sensed by the device.
[0133] The ability to seamlessly measure and wirelessly transmit critical interface pressure data greatly augments the ability to care for patients suffering from VSUs. Beyond VSUs, medical compression stockings have demonstrated clinical benefit for other lower leg issues including vein varicosities and deep vein thrombosis. The described exemplary device represents a major innovation in the field of medical compression stockings.
[0134] Calibration of the functional fabrics and sensors described herein plays an important role in providing therapeutic benefits and are illustrated in
Example 2: Compression Garments for Measurement of Limb Volume
[0135] Beyond interface pressure, measurement of limb volume also holds significant clinical value. The measurement of limb volume, for example leg volume, is commonly performed by modeling the leg as a cylinder and determining volume based on circumference with tape measures. Hence, the measurement of leg volume is labor intensive and lacks sensitivity to small but still meaningful changes in leg volume. Furthermore, tape measure assessments of leg volume do not provide an understanding of the nature of edema.
[0136] A first example method of assessing leg volume is the use of bioimpedance. Bioimpedance provides a measurement of passive electrical properties that can be used to characterize biological tissue. By measuring the impedance of tissue in response to stimulatory currents, and voltages of varying frequencies, predictions can be made of a limb's fluid status or ischemic state. In the case of leg edema, the excess extracellular fluid leads to changes in the electrical impedance of the tissue. Measurement of bioimpedance is cost-effective, non-invasive, repeatable, and sensitive.
[0137] In embodiment, bioimpedance is utilized to measure limb volume. Bioimpedance provides a measurement of passive electrical properties that can be used to characterize biological tissue. By measuring the impedance of tissue in response to stimulatory currents, and voltages of varying frequencies, predictions can be made of a limb's fluid status or ischemic state. In the case of leg edema, the excess extracellular fluid leads to changes in the electrical impedance of the tissue. Measurement of bioimpedance is cost-effective, non-invasive, repeatable, and sensitive.
[0138] The use of bioimpedance to assess biological phenomena is well established. Those skilled in the art will know that standard ECG electrodes (electrochemical electrodes of AgAgCl) or metallic plunge probes (platinum, gold, or stainless steel) can be applied on the tissue surface in order to determine bioimpedance. Another method of determining bioimpedance involves a tetrapolar impedance measurement system. This reduces the contribution of motion artifact and measurement of impedance associated with the skin-sensor interface. Example tetrapolar impedance systems are provided in
[0139] The placement of the various sensors is important in the assessment of limb volume. We employ standard anatomical locations (area of maximum girth of the gastrocnemius muscle or insertion of the gastrocnemius muscle at the Achilles tendon) to ensure a normalized distance for patients of varying leg lengths.
[0140] The frequency and current of the AC signal is selected to minimize the risk of patient harm. Some embodiments utilize frequency ranges of 5 to 100 kHz for assessing biological tissue volume. In an embodiment, 50 kHz frequency is used.
[0141] Bioimpedance Method 1 (
[0142] Bioimpedance Method 2 (
[0143] A second example method of determining leg volume is through modeling the lower leg as a cylinder. As described in
[0144] With pressure and tension measurements, the radius of curvature (p) can be derived using the following equation:
p=T.sub.1Eqn. 1
Assuming that the radius of curvature at the location of the sensor is tangential to the lower limb, then the radius of curvature calculated by the sensor would equal the lower limb radius (r.sub.limb).
[0145] The volume of the limb can be determined using this derived cylinder radius and the length of the limb, which is a fixed value:
V=*r.sub.limb*limb lengthEqn. 2
Since limb length is fixed, changes in r.sub.limb can be used to express leg volume changes.
Example 3: Epidermal Interface Pressure Sensor (EIPS)
[0146] In this example, provided is a soft, flexible device platform containing a pressure sensor. In some embodiments, the device platform exhibits a Young's modulus comparable to natural skin. In some embodiments, the device is encapsulated in PDMS to reduce contract stress, protect sensors and communications system on the device and improve sensor performance, for example, piezoelectric pressure sensor performance.
[0147] In some embodiments, the provided systems or methods are mechanically invisible or user invisible. User invisibility is an important consideration for sensors designed for long-term use. In patients with medical problems such as lower leg edema or chronic venous insufficiency, the skin is particularly sensitive to irritation, susceptible to injury, and prone to infection. Thus, user invisibility is an important medical consideration. The determination of user invisibility can be achieved in two ways. From a quantitative method, user invisibility can be determined by measuring skin temperature. When skin temperature exceeds a certain temperature, the sensor can alert the user for the need to potentially remove the device. Other onboard warning methods may include assessments of blood flow or skin redness, which may also indicate the need for sensor removal.
[0148] The user can also be asked to respond to directed questions via SMS text messages or mobile phone application prompts. The user can indicate if they are experiencing any pain, irritation, itching, or redness related to the device at specified time intervals.
[0149] Achieving a small sensor profile directed by in-depth mechanical modeling ensures accurate sensing. A key problem with interface sensors for pressure is hammocking error (
[0150] We modeled two different encapsulation methods compared to the bare sensor based on their inherent mechanical properties. Our modeling indicates that an encapsulated sensor with a larger PDMS skin interface yielded the best mechanical results as illustrated in
[0151] Experiments were conducted to compare the various sensor configurations described herein, where conductance was measured while using a sphygmomanometer to apply incremental increasing pressures. The sensor was placed between two rigid boards
[0152] Results demonstrate that encapsulation with a larger PDMS interface with the skin compared to the sensor alone enabled more discriminatory ability in bench testing. As in
Example 4: Novel Clinical Metrics
[0153] The ability to accurately measure and store interface pressure along with other important biometric data (temperature and leg volume) enables the determination of novel, useful clinical metrics. For example, the sensor can be employed to test fabric failure over time. Fabric failure can be expressed as a change in interface pressure that is supplied by the compression stocking in different body positions.
[0154] In one example, a pressure sensor averages interface pressure at supine position for 30 second. Then, the sensor averages interface pressure at standing position for 30 second. The Difference of the interface pressure is taken to produce a static stiffness index (SSI). If interface pressure difference >20% of manufacturer specifications, then it indicates to user and clinician that a new garment is needed, enabling a simple method to enable testing of fabric failure without the need for specialized equipment.
[0155] Another example is a device that measures pressure and limb volume together, allowing for a new clinical index. This applied pressure over limb volume change would represent an individual patient's tissue response to therapeutic compression. Certain individuals may require higher interface pressure to achieve the same edema reduction compared to others. This enables personalized delivery of compression therapy that is adaptive.
[0156] Beyond continuous sampling, the provided systems can be modified to provide cumulative pressure sensing. For example, the sensor output can be used to continuously charge a capacitor in the circuit. The total capacitance at the end of a fixed time period can provide a single metric of applied pressure over time or total applied pressure. This would take into account patient adherence and alterations in pressure with body position but summing all pressures sensed throughout a given time period.
[0157] The sensor may also be employed to track wound healing over time. Venous stasis ulcers are directly secondary to chronic venous insufficiency (which leads to leg edema). The sensor can incorporate skin temperature as a way to track infection. The sensor can also utilize temperature to sense and quantify blood flow directly to the wound bed, which is important for wound healing.
Example 5: Epidermal Electronics in Compression Stockings
[0158] Inelastic and elastic compression stockings are a common treatment for a range of conditions including chronic venous insufficiency, venous stasis ulcers (>35 mmHg improves healing), lipodermatosclerosis, and lymphedema. Treatment incorporates at least two aspects as shown in
[0159] Currently, there are several clinical needs for improved treatment using compression stockings: [0160] 1. Need for a continuous measurement system for interface pressure to understand medicine of compression [0161] 2. Need for assessment of patient adherence and real-world usage to understand dose of compression [0162] 3. Need for data storage and transmissionideally wireless [0163] 4. Need for integration with existing compression stockings [0164] 5. Need for a method to assess garment performance failure
[0165] Examples of pressure sensors used in research surrounding compression treatment are provided in
[0166] Academic research and literature has proposed several design criteria which may be important for developing compression stocking devices as described in Table 1. Two potential commercial sensors were compared under the design criteria, also shown in Table 1.
TABLE-US-00001 TABLE 1 Proposed design criteria in literature (source: Derm. Surg. 2006, 32: 224-233) EIPS as Criteria PicoPress VenoSense described herein Reliability +++ + ++ Accuracy +++ ++ ++ Low hysteresis +++ + ++ Thin ++ +++ Continuous Output + +++ Accuracy ++ + ++ Variable Sensor Sizes +++ Wireless Transmission +++ +++ Temperature +++ Suitable for Daily Use + +++ Range (0-100 mmHg) +++ +++ +++ Commercially Available +++
[0167] The present example was designed to address the following clinical needs: [0168] 1. Need for a continuous measurement system for interface pressure [0169] 2. Need for data transmissionideally wireless capabilities [0170] 3. Need for assessment of patient adherence and real-world usage [0171] 4. Need for integration with existing compression stocking garments [0172] 5. Need for a method to assess garment performance failure
Which in turn lead to the following technical design criteria: [0173] 1. Continuous interface pressure sensing (0-100 mmHg+/1 mmHg) [0174] 2. Provide wireless transmission of onboard sensor data for additional analysis [0175] 3. Provide onboard temperature sensing to quantify pressure sensor [0176] 4. Presents no risk to skin irritation, or skin injury using a flexible, epidermal interface with at least 1 week of use [0177] 5. Enable straightforward integration with any existing compression garment [0178] 6. Less than 20% error vs. gold-standard pressure sensor (PicoPress) across the full range of the device [0179] 7. Enable unique identification of patient information [0180] 8. Provide method for onboard testing of compression stocking performance
[0181] Intrusive rigid sensor causes deformation of the limb and/or the stocking in what is known as hammocking error, which is described in
[0182] The physics of the sensor, stocking and limb can be described physically in
p=T(Eqn 1)
As previously described, where
T=T.sub.1+T.sub.2(Eqn 3)
Assuming linear elasticity, the compatibility equation becomes:
If the flexural rigidity of the device is far smaller than the value of the compression stocking then:
where E.sub.1d.sub.1<<E.sub.2d.sub.2, then:
These variables and relationships are illustrated in
[0183] Encapsulating the wireless device and/or sensors in two layers of polyester film on which silver and/or a layer of piezoresistive ink will improve the accuracy and durability of the sensors (this configuration may be referred to herein as FlexiForce). This encapsulation is cost effective, promotes accuracy and linearity but has potential problems with repeatability, hysteresis and strain isolation. To address these issues, we have used three strategies: 1) reduce the thickness of the wireless device/sensor to less than t3 mm to reduce hammocking error; 2) strain isolate the sensor to improve signal stability and 3) replicate the modulus and strain of the sensor with than of skin to achieve mechanical invisibility and ensure patient acceptance.
[0184] An example compression stocking kit with a plurality of wireless devices and important positions is show in
TABLE-US-00002 TABLE 2 Positions shown in FIG. 36 B Ankle at minimum point of girth B1 Area where Achilles tendon changes into calf muscle (approx. 10-15 cm proximal to medial malleolus) C Calf at its maximum girth D Just below the tibial tuberosity E Center of the patella and over the back of the knee F Between K and E (mid-thigh, between patella and groin) G 5 cm below the center point of the crotch H Greatest lateral trochanteric projections of the buttock K Center point of the crotch
[0185] An advantage provided by the systems, methods and devices described herein is that a status stiffness test can be performed at set time intervals (e.g. every three months) to determine if the garment is still effective or if it has failed. These garment tests may be performed by a health professional such as a nurse or a medical assistant. An example of a stiffness test is: 1) Sensor averages interface pressure at supine position for 30 seconds; 2) Sensor averages interface pressure at standing position for 30 seconds; 3) Use the difference between the interface pressures take to produce a static stiffness index; and 4) If the interface pressure difference is greater than 20% of the manufacturer specifications, the indicate to the user and clinician that a new garment is needed.
[0186] We have developed a garment in the form of a compression stocking with the following properties:
TABLE-US-00003 Design Consideration Property Achieved Continuous Pressure Sensing 0-100 mmHg Wireless Transmission NFC Onboard Temperature Sensing NFC Thin, flexible PDMS Less than 5 mm thickness Integration with Existing Can be applied to skin Compression Stockings or cotton liner Enable unique identification NFC of patient
Example 6Wireless Stretchable and Bendable Pressure and Temperature Sensors
[0187] An integrated wireless, wearable temperature sensor is provided in
[0188] Medical Grade Temperature Sensor: Described herein is the addition of a medical-grade temperature sensor capable of accuracy of 0.1 C. This temperature sensor is thermally isolated from the external environment. The ability to sense cutaneous temperature is an important parameter in assessing local inflammation and wound healing. Elevated cutaneous temperature suggests inflammation and impending wound. Thus, the incorporation of a medical grade temperature with a pressure sensor enables advanced functionalities and the generation of novel clinical metrics relevant to wound healing.
[0189] Novel Clinical Metrics: The ability to predict wound healing with prognostic certainty is largely depend on physician visual inspection. Thus, tools capable of providing object measures of wound healing potential would be of high clinical value. In addition, the ability to detect skin inflammation indicative of the formation of a wound prior to clinical manifestation would also be of high interestthis would enable early intervention prior to formation of a significant wound.
[0190] The devices and systems described herein can combine onboard pressure, skin temperature across time. This enables the creation of novel predictive clinical metrics relevant to wound healing. For instance, a given period of therapeutic pressure over time (e.g. PressureTime index) could be set as a new threshold to assess wound closure likelihood that is confirmed by the skin temperature sensor. Alternatively, the skin temperature sensor over time can indicate a lack of response to therapeutic pressure at a given level and then provide an indicator to increase the absolute interface pressure or increase the time of pressure per day.
[0191] Further, multiple pressure and temperature sensors may be placed on the human body or human limb. This enables the creation of a pressure/temperature map. This map may be used to then assess for problem areas that warrant further attention in relationship to other sensors on the same body or limb.
[0192] Any of the devices described herein may also be integrated with bandages, wound dressings (specifically pressure ulcer wound healing products), abdominal binders, and athletic gear (e.g. compressive pants, shirts, and sleeves).
Example 7Embedded Readers to Reduce User Burden and Enable Continuous Pressure, and Temperature Reading
[0193] In some of the embodiments described herein, a smartphone or other mobile device (e.g. tablet or laptop) is necessary to power and scan the data from the device. Other embodiments include non-smartphone NFC readers and power systems to reduce user burden.
[0194] For instance, the addition of a battery-powered antennae (e.g. clipped to the outside of a compression stocking) would enable continuous sensing of pressure and temperature. An embedded antennae within a mattress would also enable continuous pressure sensing by providing continuous power.
[0195] To reduce user burden, other embodiments outside of the phone to power and read the device include a weight scale or a bathroom floor pad plugged into the wall or battery powered. This enables a user to simply step on a bathroom floor pad daily to measure skin temperature and interface pressure that is then transmitted to the cloud.
Example 8Wearable Sensor Enabled Telemedicine
[0196] The systems, methods and devices described herein may also be useful in a telemedicine-type platform, wherein the wireless sensor/garment provides useful information to a caregiver, such as a medical professional, friend or family member. Not only are the devices and methods useful in diagnostic or therapeutic applications, but can be used for training and rehabilitation. This is reflected in the devices and systems having two-way communication so that information may sent externally for action to a caregiver and commands received by the medical sensor.
[0197] Nursing care and home care for wounds is a time-intensive process. The application, removal, and changing of dressing is largely done without standardization. The sensor reported here would potentially be a useful component of a telemedicine/remote monitoring enabled system. For instance, the sensor may detect a decrease in therapeutic pressure between a therapeutic compression garment and the skin. This would trigger a message or indicator through the smartphone to the cloud that leads to a nursing care event (e.g. re-wrapping). Or, the sensor may detect elevated skin temperature indicative of wound worsening or a new infection triggering a notification to a caregiver or healthcare provider.
STATEMENTS REGARDING INCORPORATION BY REFERENCE AND VARIATIONS
[0198] All references throughout this application, for example patent documents including issued or granted patents or equivalents; patent application publications; and non-patent literature documents or other source material; are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in this application (for example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference).
[0199] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention and it will be apparent to one skilled in the art that the present invention may be carried out using a large number of variations of the devices, device components, methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional composition and processing elements and steps.
[0200] When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups are disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and subcombinations possible of the group are intended to be individually included in the disclosure. Additionally, unless otherwise specified, all isotopic variants of compounds disclosed herein are intended to be encompassed by the disclosure. Specific names of compounds are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same compounds differently.
[0201] Every formulation or combination of components described or exemplified herein can be used to practice the invention, unless otherwise stated.
[0202] Whenever a range is given in the specification, for example, a temperature range, a modulus range, a number range, a pressure range, a physical dimension, a mechanical property or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.
[0203] All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the invention pertains. References cited herein are incorporated by reference herein in their entirety to indicate the state of the art as of their publication or filing date and it is intended that this information can be employed herein, if needed, to exclude specific embodiments that are in the prior art. For example, when composition of matter are claimed, it should be understood that compounds known and available in the art prior to Applicant's invention, including compounds for which an enabling disclosure is provided in the references cited herein, are not intended to be included in the composition of matter claims herein.
[0204] As used herein, comprising is synonymous with including, containing, or characterized by, and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, consisting of excludes any element, step, or ingredient not specified in the claim element. As used herein, consisting essentially of does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein any of the terms comprising, consisting essentially of and consisting of may be replaced with either of the other two terms. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.
[0205] One of ordinary skill in the art will appreciate that starting materials, biological materials, reagents, synthetic methods, purification methods, analytical methods, assay methods, and biological methods other than those specifically exemplified can be employed in the practice of the invention without resort to undue experimentation. All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.