Methods for implementing electronic skin and physiological signal monitoring systems

Abstract

This invention discloses a method for implementing electronic skin and a physiological signal monitoring system. The electronic skin provided in this application includes: a sensing platform and a plurality of sensing units disposed on the sensing platform; the sensing platform has an island-bridge structure, and includes a first material and a second material, wherein the first material is a stretchable material and the second material is a non-stretchable material; the sensing platform is formed by bonding the second material to the first material after silanization treatment; the sensing units are disposed on the second material; each sensing unit includes a sensitive film and electrodes, and is used to measure temperature, humidity, or oxygen. This embodiment of the application realizes a stretchable sensor through an island-bridge structure sensing platform; by measuring signals through a sensitive film, multi-target measurement can be achieved, improving the stretchability of the electronic skin, and simultaneously enabling convenient monitoring. This invention can be widely applied in the field of signal measurement technology.

Description

Technical Field

[0001] This invention relates to the field of signal measurement technology, and in particular to a method for implementing electronic skin and a physiological signal monitoring system. Background Technology

[0002] In the management of chronic diseases, continuous monitoring and data analysis of the condition are crucial. Traditional medical monitoring methods are often limited by time and location, making real-time monitoring of the condition difficult. The emergence of portable wearable sensing devices has changed this situation, making it possible to continuously collect patients' physiological information. However, wearable sensing devices are mostly rigid structures, which are easily affected by mechanical damage and may malfunction. Therefore, it is necessary to endow sensors with flexibility and stretchability, so that the devices can better conform to the surface of human skin or clothing, improving their stability and reliability when the body is in motion. In addition, compared with monitoring a single physiological signal, monitoring the results of multiple physiological signals will provide doctors with more effective information for disease diagnosis and treatment. Among them, body temperature, body surface humidity, exhaled breath humidity, and TcPO2 are important physiological signals for patients with chronic diseases such as diabetic foot, chronic lower limb severe ischemia, and obstructive sleep apnea-hypopnea syndrome. Therefore, developing flexible and stretchable multifunctional physiological signal sensing devices can monitor and record changes in relevant vital signs of patients with chronic diseases in real time, effectively assisting doctors in disease diagnosis and treatment.

[0003] Skin contains numerous receptors that encode environmental stimuli, enabling it to sense pressure, temperature, and humidity, thus establishing a connection between the individual and their surroundings. Materials that can contact the skin and perform signal measurements are being used in various sensors. Among these, hydrogels, with their stretchability and multi-sensitivity, offer convenience but also introduce problems such as interference with response signals and crosstalk between multiple stimuli. Many methods have been developed to mitigate the effects of strain, including serpentine, spiral, and wrinkled structures, as well as composite materials. However, existing structural and material designs are either overly complex or insufficient in effectively isolating strain. Simultaneously, the coupling interference of multiple signals makes it difficult to achieve high sensitivity and selectivity for detecting different stimuli in multifunctional sensors. Researchers have explored different approaches to address and minimize crosstalk associated with multiple stimuli. For example, encapsulation can help isolate the effects of ambient humidity and gases on sensing, but it may not be suitable for humidity and gas sensing itself. Creating unique sensing mechanisms for specific stimuli can help distinguish various stimulus sources. However, due to the water-containing nature of hydrogels, it is difficult to eliminate the influence of ambient humidity on sensing. Therefore, effectively addressing the crosstalk problem poses a significant obstacle to multifunctional sensing in hydrogels. Summary of the Invention

[0004] The purpose of this invention is to at least partially solve one of the technical problems existing in the prior art.

[0005] Therefore, the purpose of this invention is to provide a highly efficient method for implementing electronic skin and a physiological signal monitoring system.

[0006] To achieve the above-mentioned technical objectives, the technical solutions adopted in the embodiments of the present invention include the following aspects:

[0007] On one hand, embodiments of the present invention provide an electronic skin, comprising: a sensing platform and a plurality of sensing units disposed on the sensing platform; the sensing platform is an island-bridge structure, comprising a first material and a second material, the first material being a stretchable material and the second material being a non-stretchable material; the sensing platform is formed by bonding the second material to the first material after silanization treatment; the sensing units are disposed on the second material; the sensing units include a sensitive film and electrodes, and the sensing units are used to measure temperature, humidity, or oxygen. This embodiment of the application realizes a stretchable sensor through an island-bridge structure sensing platform; by measuring signals through a sensitive film, multi-target measurement can be achieved, improving the stretchability of the electronic skin, and simultaneously enabling convenient monitoring.

[0008] In addition, the electronic skin according to the above embodiments of the present invention may also have the following additional technical features:

[0009] Furthermore, in the electronic skin of this embodiment, the sensing platform has a three-layer structure: the first layer is used to measure humidity and oxygen in the air, the second layer is used to measure the body temperature of the object, and the third layer is used to measure the humidity and TcPO2 concentration of the skin surface when in contact with the skin surface of the object.

[0010] Furthermore, in one embodiment of the present invention, the first material comprises PDMS, the second material comprises PET, and the sensitive film comprises a PAM / Carr-LiBr hydrogel film.

[0011] On the other hand, embodiments of the present invention propose a method for implementing electronic skin, which is used to prepare the above-mentioned electronic skin, the method comprising:

[0012] Take several metal sheets and prepare a first material thin film on the metal sheets as a substrate;

[0013] The cut second material film was subjected to silanization treatment to obtain several islands;

[0014] The islands are bonded to the substrate, electrodes are fixed on each island, and a sensitive film is covered to obtain the electronic skin.

[0015] Furthermore, in one embodiment of the present invention, the silanization treatment of the cut second material film to obtain a plurality of islands includes:

[0016] The surface of the second material film was cleaned with deionized water and isopropanol, and then subjected to air plasma treatment for a first duration.

[0017] The treated second material film is immersed in APTES solution and heated at a first temperature for a second duration to perform silanization treatment.

[0018] The second material film was removed, rinsed with deionized water, and dried with a nitrogen gun to obtain several islands.

[0019] Furthermore, in one embodiment of the present invention, the step of bonding the island to the substrate includes:

[0020] The surfaces of the first material film and the silanized second material film are subjected to air plasma treatment for a third duration.

[0021] The first material film and the second material film, after being bonded together with Dragon Skin prepolymer, are cured at a second temperature for a fourth duration to obtain a sensing platform.

[0022] Furthermore, in one embodiment of the present invention, the sensitive film comprises a PAM / Carr-LiBr hydrogel film, which is prepared by the following steps:

[0023] Weigh out acrylamide, carrageenan, N-methylenebisacrylamide, potassium chloride, photoinitiator and deionized water in a predetermined ratio, heat in an oil bath at a third temperature for a fifth time to obtain a precursor solution;

[0024] PDMS prepolymer was prepared by spin-coating the PDMS prepolymer onto an aluminum sheet at a preset rotation speed. After curing, the PDMS surface was subjected to plasma treatment for a duration of six hours.

[0025] The precursor solution was dropped onto plasma-treated PDMS and then spin-coated to obtain a thin precursor layer.

[0026] After the precursor thin film was cryogenically treated, LiBr solution was drop-coated onto the surface of the precursor thin film and placed under a UV lamp for photoinitiation for 2 hours to obtain a PAM / Carr-LiBr hydrogel film.

[0027] Furthermore, in one embodiment of the present invention, the sensitive film comprises an ion gel film, which is prepared by the following steps:

[0028] Preparation of ion gel precursor solution using acetone;

[0029] The ion gel precursor solution was poured onto an aluminum substrate and kept for seven hours until the solvent completely evaporated to obtain the ion gel.

[0030] Furthermore, in one embodiment of the present invention, the electronic skin is measured through the following steps:

[0031] The first temperature, first humidity, and first oxygen level are measured using the electronic skin.

[0032] The first temperature is determined to be the temperature measurement result. Based on the temperature measurement result, the first humidity is decoupled to obtain the humidity measurement result.

[0033] The first oxygen is decoupled based on the temperature measurement result and the humidity measurement result to obtain the oxygen measurement result.

[0034] On the other hand, embodiments of the present invention provide a physiological signal monitoring system, including: electronic skin, control module, and wireless module as described above;

[0035] The control module is used to send control signals to enable the electronic skin to measure temperature, humidity or oxygen, obtain measurement signals, process the measurement signals, and send the processed measurement signals to the target terminal through the wireless module.

[0036] The electronic skin provided in this invention includes: a sensing platform and a plurality of sensing units disposed on the sensing platform; the sensing platform has an island-bridge structure, and includes a first material and a second material, wherein the first material is a stretchable material and the second material is a non-stretchable material; the sensing platform is formed by bonding the second material to the first material after silanization treatment; the sensing units are disposed on the second material; each sensing unit includes a sensitive film and an electrode, and is used to measure temperature, humidity, or oxygen. This embodiment of the invention realizes a stretchable sensor through an island-bridge structure sensing platform; by measuring signals through a sensitive film, multi-target measurement can be achieved, improving the stretchability of the electronic skin, and simultaneously enabling convenient monitoring. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following description is provided with accompanying drawings of the relevant technical solutions in the embodiments of the present invention or the prior art. It should be understood that the accompanying drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0038] Figure 1A schematic diagram illustrating an application scenario of an embodiment of the electronic skin provided by the present invention;

[0039] Figure 2 A schematic diagram of the structure of one embodiment of the electronic skin provided by the present invention;

[0040] Figure 3(a) is a graph showing the changes in oxygen and humidity provided by the temperature sensing unit of the present invention;

[0041] Figure 3(b) is a graph showing the changes in oxygen and temperature of the humidity sensing unit provided by the present invention.

[0042] Figure 3(c) is a graph showing the changes in temperature and humidity of the oxygen sensing unit provided by the present invention.

[0043] Figure 4(a) is a schematic diagram of an embodiment of the self-calibration sensor provided by the present invention;

[0044] Figure 4(b) is a surface plot of the temperature calibration of the humidity sensor provided by the present invention;

[0045] Figure 4(c) is a surface view of an embodiment of humidity calibration of oxygen sensing provided by the present invention;

[0046] Figure 4(d) is a surface view of another embodiment of the humidity calibration of the oxygen sensor provided by the present invention;

[0047] Figure 5 A schematic diagram illustrating the principle of the stretch insensitivity mechanism provided by this invention;

[0048] Figure 6(a) is a schematic diagram of the experimental results of the adhesive strength of the first material and the second material directly bonded together according to the present invention;

[0049] Figure 6(b) is a schematic diagram of the experimental results of the bonding strength of the first material and the second material DS provided by the present invention;

[0050] Figure 6(c) is a schematic diagram of the adhesive strength test results of the first material and the second material provided by the present invention after silanization.

[0051] Figure 7 A schematic diagram showing the comparison of the resistance of the electronic skin provided by this invention and the bulk hydrogel of related technologies under dynamic stretching.

[0052] Figure 8(a) shows the response curves of the temperature sensing unit to gradient temperature under different tensile strains provided by the present invention.

[0053] Figure 8(b) shows the resistance change curve under dynamic stretching at 45°C provided by the present invention;

[0054] Figure 8(c) shows the response curves of the humidity sensing unit to gradient humidity under different tensile strains provided by the present invention.

[0055] Figure 8(d) shows the comparison curves of resistance changes of dry and wet fingers under dynamic stretching provided by the present invention;

[0056] Figure 8(e) shows the response curves of the oxygen sensing unit to gradient oxygen under different tensile strains provided by the present invention.

[0057] Figure 8(f) shows the current variation curves of O2 and N2 under dynamic stretching provided by the present invention;

[0058] Figure 9 This is a schematic diagram illustrating the implementation path of the physiological signal monitoring system provided by the present invention;

[0059] Figure 10(a) shows the effect curve of wrist movement on humidity response when the sensor is worn on the wrist, as provided in this application.

[0060] Figure 10(b) shows the effect curve of dynamic stretching provided in this application on humidity applications such as skin moisture, air humidity and breathing depth.

[0061] Figure 10(c) shows the response change curves of the temperature and humidity sensing unit before and after motion provided in this application;

[0062] Figure 10(d) shows the TcPO2 variation curve at the wrist measured using a multifunctional sensor provided in this application;

[0063] Figure 11 This is a schematic diagram illustrating the application scenarios and monitoring results of the physiological signal monitoring system provided by the present invention;

[0064] Figure 12 This is a schematic diagram of the hydrogel film preparation process provided by the present invention;

[0065] Figure 13 This is a schematic diagram of the silanization process provided by the present invention. Detailed Implementation

[0066] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0067] In the management of chronic diseases, continuous monitoring and data analysis are crucial. Traditional medical monitoring methods are often limited by time and location, making real-time monitoring of the condition difficult. The emergence of portable wearable sensing devices has changed this situation, making it possible to continuously collect patients' physiological information. Doctors can analyze and judge the progression of chronic diseases through real-time collected physiological signal data, and adjust treatment plans in a timely manner to achieve the best treatment results; they can even capture some abnormal signals that are difficult to detect by traditional examination methods, providing important evidence for early diagnosis and intervention. However, wearable sensing devices are mostly rigid structures, which are easily affected by mechanical damage and may malfunction. Therefore, it is necessary to endow sensors with flexibility and stretchability so that the devices can better fit the surface of human skin or clothing, improving their stability and reliability when sensing during human movement. In addition, compared with monitoring a single physiological signal, combining the monitoring results of multiple physiological signals will provide doctors with more effective information for diagnosing and treating diseases. Among them, body temperature, body surface humidity, exhaled air humidity, and TcPO2 are important physiological signals for patients with chronic diseases such as diabetic foot, chronic lower limb severe ischemia, and obstructive sleep apnea-hypopnea syndrome. Therefore, the development of flexible and stretchable multifunctional physiological signal sensing devices can monitor and record changes in relevant vital signs of patients with chronic diseases in real time, which will effectively assist doctors in the diagnosis and treatment of diseases.

[0068] As one of the largest organs in the human body, skin possesses considerable toughness and elasticity, enabling it to withstand various mechanical deformations caused by body movement. Stretchable electronic devices with skin-like mechanical properties can adapt to irregular surfaces and withstand various deformations. Furthermore, skin contains numerous receptors that encode environmental stimuli, sensing pressure, temperature, and humidity, thus establishing a connection between the individual and their surroundings. To replicate the somatosensory functions of human skin, researchers are focusing on developing skin-like multifunctional sensors capable of detecting various forms of stimuli. Over the past few decades, researchers have developed devices that integrate multiple sensing modalities for applications in robotics, health monitoring, artificial intelligence, and the Internet of Things. A range of materials have been used to fabricate skin-like multifunctional sensors, including nanostructured metals, carbon nanotubes, conductive polymers, two-dimensional materials, and hydrogels. Among these, conductive hydrogels are a promising candidate. Functionalized hydrogels exhibit ionic conductivity, allowing for direct use of electrical parameters as response signals for convenient signal acquisition; high stretchability, enabling them to conform to various irregular surfaces such as the human body, improving wearing comfort and practicality; multiple sensitivities, enabling multifunctional sensing; and high transparency, making them suitable for military operations requiring stealth or enhancing aesthetics. However, mechanical deformation alters the conductivity of most hydrogels, affecting the stability and accuracy of hydrogel-based sensors. The varying sensitivities of hydrogels can lead to crosstalk issues, complicating the accurate and simultaneous detection of multiple complex stimuli. Therefore, there is a need to develop stretch-insensitive, crosstalk-free, multifunctional flexible sensing devices to achieve stable monitoring of patients' physiological signals.

[0069] While the stretchability and multiple sensitivities of hydrogels offer convenience, they also introduce problems such as interference with response signals and crosstalk between multiple stimuli. Numerous methods have been developed to mitigate the effects of strain, including serpentine, helical, and wrinkled structures, as well as composite materials. However, existing structural and material designs are either overly complex or insufficient in effectively isolating strain. Parallel island-bridge structures offer another approach to minimizing strain interference. Local stiffness influences strain distribution during stretching; increasing the stiffness of specific regions can help isolate the effects of strain on device performance. However, modulus mismatch often leads to separation between island-bridge regions, resulting in structural damage and device failure.

[0070] The coupling interference of multiple signals makes it difficult to achieve high sensitivity and selectivity in multifunctional sensors for detecting different stimuli. Researchers have explored different methods to address and minimize crosstalk associated with multiple stimuli. For example, encapsulation can help isolate the effects of ambient humidity and gases on sensing, but it may not be suitable for humidity and gas sensing itself. Creating unique sensing mechanisms for specific stimuli can help distinguish various stimulus sources. However, due to the water-containing nature of hydrogels, it is difficult to eliminate the influence of ambient humidity on sensing. Therefore, effectively solving the crosstalk problem poses a significant obstacle to multifunctional sensing in hydrogels.

[0071] Therefore, there is a need to develop a multifunctional stretchable sensor that can simultaneously monitor multiple target physiological signals and is unaffected by tensile strain, so as to achieve convenient monitoring of human health or medical environment comfort.

[0072] The electronic skin according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings. First, refer to the accompanying drawings... Figure 1 and attached Figure 2 An electronic skin according to an embodiment of the present invention is described, comprising: a sensing platform and a plurality of sensing units disposed on the sensing platform;

[0073] The sensing platform is an island bridge structure, comprising a first material and a second material, wherein the first material is a stretchable material and the second material is a non-stretchable material; the sensing platform is formed by bonding the second material to the first material after silanization treatment; the sensing unit is disposed on the second material.

[0074] The sensing unit includes a sensitive thin film and electrodes, and is used to measure temperature, humidity, or oxygen.

[0075] Reference Figure 1 As shown, the electronic skin in this embodiment can measure a variety of human body signals to monitor human health. Figure 1 In this process, an electronic skin is worn on the wrist, which collects data through hardware circuitry, transmits the data wirelessly to a host computer / server for processing, and displays the data on a terminal.

[0076] Optionally, in the electronic skin of this embodiment of the invention, the sensing platform has a three-layer structure: the first layer is used to measure humidity and oxygen in the air, the second layer is used to measure the body temperature of the object, and the third layer is used to measure the humidity and TcPO2 concentration of the skin surface when in contact with the skin surface of the object.

[0077] In some possible implementations, of course, this application does not limit the specific structure of the sensing platform, and those skilled in the art can make adjustments according to actual needs.

[0078] Optionally, in the electronic skin of this embodiment of the invention, the first material includes PDMS, the second material includes PET, and the sensitive film includes a PAM / Carr-LiBr hydrogel film.

[0079] In some possible implementations, this application does not limit the specific types of the first material, the second material, or the sensitive film.

[0080] On the other hand, the present invention provides a method for realizing electronic skin, for preparing the above-mentioned electronic skin, comprising:

[0081] Take several metal sheets and prepare a first material thin film on the metal sheets as a substrate;

[0082] The cut second material film was subjected to silanization treatment to obtain several islands;

[0083] The islands are bonded to the substrate, electrodes are fixed on each island, and a sensitive film is covered to obtain the electronic skin.

[0084] Optionally, in the implementation method of the electronic skin in this embodiment of the invention, the step of silanizing the cut second material film to obtain several islands includes:

[0085] The surface of the second material film was cleaned with deionized water and isopropanol, and then subjected to air plasma treatment for a first duration.

[0086] The treated second material film is immersed in APTES solution and heated at a first temperature for a second duration to perform silanization treatment.

[0087] The second material film was removed, rinsed with deionized water, and dried with a nitrogen gun to obtain several islands.

[0088] Optionally, in the method for implementing the electronic skin in this embodiment of the invention, the step of bonding the island to the substrate includes:

[0089] The surfaces of the first material film and the silanized second material film are subjected to air plasma treatment for a third duration.

[0090] The first material film and the second material film, after being bonded together with Dragon Skin prepolymer, are cured at a second temperature for a fourth duration to obtain a sensing platform.

[0091] Optionally, in the implementation method of the electronic skin in this embodiment of the invention, the sensitive film comprises a PAM / Carr-LiBr hydrogel film, which is prepared by the following steps:

[0092] Weigh out acrylamide, carrageenan, N-methylenebisacrylamide, potassium chloride, photoinitiator and deionized water in a predetermined ratio, heat in an oil bath at a third temperature for a fifth time to obtain a precursor solution;

[0093] PDMS prepolymer was prepared by spin-coating the PDMS prepolymer onto an aluminum sheet at a preset rotation speed. After curing, the PDMS surface was subjected to plasma treatment for a duration of six hours.

[0094] The precursor solution was dropped onto plasma-treated PDMS and then spin-coated to obtain a thin precursor layer.

[0095] After the precursor thin film was cryogenically treated, LiBr solution was drop-coated onto the surface of the precursor thin film and placed under a UV lamp for photoinitiation to obtain a PAM / Carr-LiBr hydrogel film.

[0096] Optionally, in the method for implementing electronic skin in this embodiment of the invention, the sensitive film includes an ion gel film, which is prepared by the following steps:

[0097] Preparation of ion gel precursor solution using acetone;

[0098] The ion gel precursor solution was poured onto an aluminum substrate and kept for seven hours until the solvent completely evaporated to obtain the ion gel.

[0099] Optionally, in the implementation method of the electronic skin in this embodiment of the invention, the electronic skin is measured through the following steps:

[0100] The first temperature, first humidity, and first oxygen level are measured using the electronic skin.

[0101] The first temperature is determined to be the temperature measurement result. Based on the temperature measurement result, the first humidity is decoupled to obtain the humidity measurement result.

[0102] The first oxygen is decoupled based on the temperature measurement result and the humidity measurement result to obtain the oxygen measurement result.

[0103] It is evident that the content of the above electronic skin embodiments is applicable to this method embodiment. The specific functions implemented in this method embodiment are the same as those in the above electronic skin embodiments, and the beneficial effects achieved are also the same as those achieved in the above electronic skin embodiments.

[0104] On the other hand, embodiments of the present invention provide a physiological signal monitoring system, including: electronic skin, control module, and wireless module as described above;

[0105] The control module is used to send control signals to enable the electronic skin to measure temperature, humidity or oxygen, obtain measurement signals, process the measurement signals, and send the processed measurement signals to the target terminal through the wireless module.

[0106] Similarly, the content of the above method embodiments is applicable to this monitoring system embodiment. The specific functions implemented by this monitoring system embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0107] The following is a detailed description of the electronic skin, its implementation method, and physiological signal monitoring system provided in this application, using a specific embodiment:

[0108] Applications of this technology include physiological signal sensors and chronic disease treatment devices.

[0109] This invention, a multifunctional physiological signal monitoring electronic skin, firstly utilizes sensitive thin-film materials with multiple sensitivities (i.e., the sensitive films in this application, such as hydrogel films and ionogel films) to monitor stimulation signals such as temperature, humidity, and O2 in real time. Simultaneously, it achieves self-calibrating sensing among multiple stimuli by combining different sensing mechanisms with physical isolation. Furthermore, using materials A and B with a large modulus difference, a rigid-flexible "island bridge" structure is designed to effectively isolate signal interference caused by tensile strain and bending. Material A (i.e., the first material of this application) has a low modulus and typically possesses flexibility and stretchability, such as polydimethylsiloxane (PDMS), platinum-catalyzed silica gel (Ecoflex), and styrene-butadiene block copolymer (SEBS). Material B (i.e., the second material of this application) has a high modulus and is typically a rigid, non-stretchable material, such as polyethylene terephthalate (PET), ABS plastic (Acrylonitrile ButadieneStyrene plastic), and polymethyl methacrylate (PMMA). Furthermore, silanization treatment strengthens the chemical anchoring between materials A and B, reducing the risk of structural failure due to modulus mismatch. This invention uses PDMS (material A) and PET (material B) as example materials for the island-bridge structure, and polyacrylamide / κ-carrageenan-LiBr (PAM / Carr-LiBr) hydrogel film as an example material for the sensitive film. Finally, a Bluetooth multi-channel sensing circuit was designed and developed, and a multifunctional sensor was integrated with it to form a multifunctional wireless physiological signal sensing electronic skin system (such as...). Figure 1 (As shown). The entire system consists of three parts: a multifunctional sensor, a wireless transmission circuit, and a signal receiving terminal. This system can monitor physiological signals such as body temperature, surface humidity, respiration, and transcutaneous oxygen partial pressure (TcPO2) in real time, and transmit the sensor data to a mobile terminal for display. It is expected to be used for non-invasive diagnosis and treatment of chronic diseases such as diabetic foot, chronic lower limb ischemia, and obstructive sleep apnea-hypopnea syndrome, monitoring disease progression and assisting in the treatment of chronic diseases.

[0110] A schematic diagram of the strain-insensitive multifunctional electronic skin in this invention is shown below. Figure 2 As shown, it includes a strain-insensitive sensing platform and six sensing units (understandably, the number of sensing units can be adjusted). Figure 2(For illustrative purposes only). Each sensing unit consists of a PAM / Carr-LiBr thin film (i.e., a sensitive film) and two electrode wires. Different electrodes and applied voltages are selected based on different target stimuli to initially isolate different physiological signals at the sensing mechanism level. For the temperature sensing unit, Ag wires are used as electrodes, and an AC signal with an amplitude of 1V and a frequency of 1kHz is applied between the two electrodes. For the humidity sensing unit, the electrodes are also Ag wires, and an AC signal with an amplitude of 0.5V and a frequency of 200Hz is applied between the two electrodes. For the O2 sensing unit, both the cathode and anode are Ag wires, and a DC signal of 0.5V is applied. That is, in this embodiment, the electrodes are set to a first metal, and a first signal is applied between the electrodes to enable the electrodes to measure temperature; the electrodes are set to a second metal, and a second signal is applied between the electrodes to enable the electrodes to measure humidity; the electrodes are set to a third metal, and a third signal is applied between the electrodes to enable the electrodes to measure oxygen. The first and second signals are AC signals, and the third signal is a DC signal. The sensing platform has three layers. The first layer contains humidity and O2 sensing units to detect humidity and oxygen levels in the air. The second layer contains a temperature sensing unit to detect changes in body temperature. The third layer also contains humidity and O2 sensing units, with the two units facing outwards. When worn on the skin, it can monitor epidermal humidity and TcPO2 concentration. The PDMS in the first and third layers physically isolates the temperature from humidity and O2 interference. When the multifunctional sensor is placed under a nitrogen atmosphere and 50% O2 is introduced, the conductivity of the temperature sensing unit does not change significantly. Figure 3a (The curve in the upper middle figure). Figure 3a The curve in the lower middle figure shows that the conductivity of the temperature sensing unit did not change significantly when the humidity decreased from 75%RH to 33%RH. Figure 3a This indicates that the temperature sensing unit is not sensitive to O2 and humidity, and its temperature sensing can resist interference from other stimuli. Figure 3b The curve in the upper middle figure shows that the humidity sensing unit is not sensitive to oxygen levels. However, the response of the humidity sensing unit is affected by changes in ambient temperature. Figure 3b (The curve in the lower middle figure). Figure 3b This indicates that the humidity sensing unit can resist oxygen interference, but its conductivity is affected by temperature. Figure 3c The curves in the upper middle figure show the response of the multifunctional sensor to 10% O2 in a nitrogen atmosphere at different temperatures. The response curves do not overlap, indicating that the O2 sensing unit is affected by the ambient temperature. Figure 3c The curves in the lower part of the graph show the response of the O2 sensing unit to 10% O2 under different humidity levels. As the humidity decreases, the O2 response also gradually decreases, indicating that the O2 sensing unit is affected by the ambient humidity. Figure 3cThis explains that the O2 sensing unit is affected by both ambient temperature and humidity. Therefore, temperature sensing is unaffected by the other two stimuli, humidity sensing is only affected by temperature, while oxygen sensing is affected by both temperature and humidity. Thus, we can use accurately measurable temperature to calibrate the temperature-affected humidity sensing unit; then use the temperature and humidity sensing units to calibrate the oxygen sensing unit, achieving self-calibrating, crosstalk-free sensing between multiple stimuli, such as… Figure 4a As shown. By testing the SSIM sensor's response to gradient humidity at different temperatures, the temperature detection results can be used to... Figure 4b The temperature-humidity response composite plot shown decouples humidity-related information. By testing the response of O2 concentration gradients under different temperature and humidity conditions, and combining the temperature and humidity test results, the humidity-O2 response composite plot at different temperatures can decouple the O2 concentration-related information. Figure 4c and Figure 4d ).

[0111] The mechanism by which the multifunctional electronic skin in this invention achieves strain-insensitive sensing is as follows: Figure 5 As shown, an island-bridge structure sensing platform was fabricated using PDMS and PET, with sensing units fabricated on PET islands. When the device is stretched in a certain direction, the length of the bridge region increases along the stretching direction, while the size of the island region remains unchanged. The sensing units on the island region can still function normally without being disturbed by the stretching, thus achieving stretch insensitivity. However, due to the modulus mismatch between the island region and the bridge region, the island region is prone to detachment. Therefore, the connection between the island region and the bridge region is crucial, as it determines whether the island-bridge structure can maintain stability under various stretching and movement conditions. Figure 6a As shown, directly bonding PET and PDMS together results in only simple physical interaction and makes them prone to detachment. Introducing Dragon Skin (DS) as an adhesive between PET and PDMS improves the bonding between the island and bridge regions, preventing PET islands from detaching during normal stretching. However, after repeated lifting of the islands with tweezers, the PET still separates from the PDMS. Figure 6b Therefore, we functionalized the PET surface by grafting functionalized silane (3-aminopropyl)-triethoxysilane (APTES). Subsequently, we treated PET and PDMS with air plasma to introduce hydroxyl groups onto their surfaces, and then used DS to bond them together. At this point, covalent siloxane bonds were formed between DS and PET and PDMS, resulting in a tighter bond. Even after repeated lifting of the PET with tweezers, the island areas did not detach. Figure 6c The test results of adhesion energy between PET and PDMS under three adhesion methods show that the adhesion energy after silanization treatment reaches as high as 300 Jm. -2It is significantly superior to the other two methods. A comparison was made between the resistance changes of the bulk PAM / Carr-LiBr hydrogel and the multifunctional sensor of this invention under dynamic tension at a 50% strain level. Figure 7 The middle right image is Figure 7 The enlarged view of the boxed area in the left-middle image shows that the resistance of the bulk hydrogel changes with repeated stretching, indicating that the electrical signal of the hydrogel is easily affected by tensile strain. However, the resistance of the multifunctional sensor of this invention remains constant under dynamic stretching, demonstrating its extremely high resistance to tensile strain interference. Thanks to the island-bridge structure, the sensor's operation is able to resist tensile strain interference. Under 0%, 25%, and 50% strain conditions, the sensor can still sense temperature, humidity, and O2 normally. Figure 8a , Figure 8c , Figure 8e The response curves under the three tensile states almost overlap, indicating that the sensor's sensing is not affected by the degree of tension. In practical applications, the tensile strain encountered by the device is often dynamic rather than static. The sensor was alternately subjected to a static state of 0% strain and a dynamic tensile state of 50% strain. When a 45°C heating element was repeatedly brought close to the temperature sensing unit, the degree of resistance change was consistent regardless of whether it was in a static or 50% strain dynamic tensile state. Figure 8b When a dry finger is brought close to the humidity sensor unit, the change in resistance under 50% stride dynamic stretching is almost the same as that under 0% stride. Figure 8d When N2 and O2 are blown near the O2 sensing unit, the trend and magnitude of the current changes remain basically consistent. These test results indicate that the SSIM sensor's sensing of temperature, humidity, and oxygen is unaffected by the degree of stretching or dynamic stretching. It has the ability to stably record response signals under various stretching motion states. Figure 8 demonstrates that each sensor is unaffected by the degree of stretching or dynamic stretching. Figure 8a The response curves of the temperature sensing unit to the gradient temperature under different tensile strains are shown. Figure 8b Figure 8(c) shows the resistance change at 45°C under 50% straiin dynamic stretching; Figure 8(d) shows the resistance change of a dry and wet finger under 50% straiin dynamic stretching (Figure 8(e)); Figure 8(f) shows the response curve of an oxygen sensor unit to a gradient temperature under different tensile strains; Figure 8(d) shows the resistance change of a dry and wet finger under 50% straiin dynamic stretching (Figure 8(e)); Figure 8(f) shows the current change of O2 and N2 under 50% straiin dynamic stretching.

[0112] Figure 10 illustrates the sensor's detection of some physiological signals. The sensor was worn on the wrist, and with the wrist in relaxed, bent, and dynamically moving states, dry and wet fingers were brought close to the humidity sensing unit sequentially. Figure 10a Regardless of the wrist's position, the sensor accurately detects the approach of fingers and distinguishes the degree of moisture on the finger's surface, demonstrating its potential for joint applications. Figure 10b As shown, when the sensor is in its initial state, a dry finger is brought close to the humidity sensing unit. Subsequently, the sensor enters a 50% strain dynamic stretching state. Dry and wet fingers are brought close to the sensing unit sequentially, followed by a desiccant and a humidifier. The resistance change of the humidity sensing unit is continuously recorded. The results show that even under dynamic stretching, the sensor can still detect the approach of a finger and distinguish the degree of wetness of the finger surface. It can also distinguish changes in ambient humidity caused by the desiccant and humidifier. These results indicate that the sensor's response to humidity is not affected by dynamic stretching. Furthermore, the humidity sensing unit can distinguish between shallow and deep breathing under dynamic stretching, demonstrating its potential application in respiratory monitoring. Figure 10b Based on its multi-stimulus response capability, the sensor can also simultaneously monitor body temperature and skin moisture, such as... Figure 10c As shown. When the sensor is worn on the inside of the arm, the temperature and humidity sensing unit generates a response signal, sensing the body temperature and skin humidity at that moment. When the wearer begins to exercise, the relative conductivity of the temperature and humidity sensing unit increases, indicating that the body temperature rises due to exercise and the skin surface humidity increases due to sweating. When the wearer stops exercising, the relative conductivity of the temperature and humidity sensing unit first increases and then decreases. This indicates that even after stopping exercise, the wearer's body temperature continues to rise and the skin continues to sweat. After a period of time, the body temperature and skin surface humidity reach their peak, and then the body gradually returns to its original state. The signal changes detected by the sensor are consistent with the changes in body temperature and skin humidity before and after human exercise, indicating that the sensor developed in this project has the ability to monitor human physiological signals and has the potential for application in outdoor sports and health monitoring. In addition, we can also use this multifunctional sensor to monitor changes in TcPO2 on the skin surface. First, the sensor is worn on the inside of the wrist, then a heating pad is wrapped around the wrist to promote oxygen expulsion from the skin surface, then the heating pad is removed, and the change information of TcPO2 is obtained, such as... Figure 10d As shown, the temperature sensing unit eliminates temperature interference from the O2 sensing unit when monitoring TcPO2.

[0113] The system block diagram of the Bluetooth multi-channel sensing circuit of the present invention is as follows: Figure 9As shown. The wireless circuit powers the sensor and, through a signal conditioning module, converts the sensor's output electrical signal into a voltage signal via amplification, filtering, and boosting. This voltage signal is then acquired by the microprocessor's analog-to-digital converter. The microprocessor packages and encodes the acquired data and transmits it via serial port to the wireless transmission circuit, which then sends it to the user terminal APP. This project uses a low-power STM32 series chip as the microprocessor and a small-size surface-mount EFR32BG22 chip as the wireless transmission module. The entire system is powered by a 3.7V lithium battery, and a DC-DC power supply chip converts the 3.7V power supply voltage to other voltages to drive different chips and circuit modules.

[0114] like Figure 11 As shown, patients can wear the sensor anywhere they need. The wireless circuit will collect information such as body temperature, body surface humidity, respiratory status, and TcPO2 from the sensor and transmit the sensor signals to a mobile app in real time via Bluetooth. This data will be stored directly on the phone for review during diagnosis and treatment. Specific implementation method 1:

[0116] Preparation of hydrogel films: Weigh 15g acrylamide, 3g κ-carrageenan, 0.01g N,N-methylenebisacrylamide, 0.18g potassium chloride, 0.2g photoinitiator, and 82mL deionized water into a 100mL flask (the amounts can be adjusted proportionally). Heat in an oil bath at 96℃ for 5 hours, while simultaneously stirring the mixture at 600rpm to obtain a PAM / Carr precursor solution. Measure Dow Corning 184 and 184 curing agent in a 10:1 ratio into a plastic cup and homogenize for 60 seconds to obtain the PDMS prepolymer. Figure 12 As shown, several 5×5cm aluminum sheets were taken, and 2g of PDMS prepolymer was spin-coated onto the aluminum sheets at 400rpm for 30s. After curing, the PDMS surface was subjected to plasma treatment at 120W for 5 minutes. Approximately 5mL of PAM / Carr precursor solution was dropped onto the plasma-treated PDMS. Spin-coating was performed at 600rpm for 25s to obtain a precursor thin film. The precursor thin film was then placed in a refrigerator at 6℃ for 1 hour, where the κ-type carrageenan first network was formed under the action of potassium ions. Approximately 2mL of 50wt% LiBr solution was then dropped onto the surface of the precursor film, and the film was placed under a UV lamp for photoinitiation for 2 hours to obtain a PAM / Carr-LiBr hydrogel film.

[0117] Preparation of ionogel films: Ionogels were prepared using a one-pot method. First, 0.543 g PVDF-HFP, 1.125 g IL (EmistFSI), and 14 ml acetone were added to a beaker. To ensure uniform chemical dispersion, the solution was stirred at 25°C and 1000 rpm / min for 5 hours. Acetone was used as the polymer solvent. After stirring, a flowable ionogel precursor solution was obtained, which was poured onto an aluminum substrate and stored at 40°C for 12 hours. After complete solvent evaporation, the ionogel was obtained. By changing the weight ratio of polymer to ionic liquid, ionogels with different properties could be obtained. Specific implementation method 2:

[0119] Fabrication of a multifunctional sensor. Several 5×5cm aluminum sheets were used to prepare multiple PDMS films as flexible, stretchable substrates. 0.2mm thick PET was cut into 6×6mm sheets to serve as islands. The PET surface was cleaned with deionized water and isopropanol, and then treated with air plasma for 1 minute. The treated PET was immersed in a 5% APTES solution and heated at 80℃ for 5 minutes for silanization. The PET sheets were removed, rinsed with deionized water, and dried with a nitrogen gun. The PDMS and silanized PET surfaces were then treated with air plasma for 1 minute and 10 seconds. The PET and PDMS were bonded together using Dragon Skin prepolymer and cured at 100℃ for 30 minutes to obtain the SIIM sensing platform. The fabrication process is as follows: Figure 13 As shown in the figure. The electrodes were then fixed to both ends of the PET island using transparent tape, and a PAM / Carr-LiBr hydrogel film was then placed on top to form a sensing unit.

[0120] This application employs an island-bridge structure to design a tensile-insensitive multifunctional sensing platform. Furthermore, silanization of PET enhances the chemical anchoring between the PET island region and the PDMS bridge region, strengthening the stability of the island-bridge structure. This application's self-calibrating multimodal flexible sensing further stabilizes the island-bridge structure and effectively isolates the interference of tension on flexible sensing. While achieving multifunctional sensing, it also enables crosstalk isolation between various stimulus sources through self-calibration.

[0121] Understandably, integrating strain sensors can be used to sense the tensile strain the device experiences in real time, allowing for sensor calibration to eliminate the influence of tension. However, this would significantly increase the workload, especially when multiple sensors are integrated on the same sensing platform, where the complexity would increase several times over.

[0122] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this invention are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is altered and sub-operations described as part of a larger operation are executed independently.

[0123] Furthermore, although the invention has been described in the context of functional modules, it should be understood that, unless otherwise stated, one or more of the functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the invention. Rather, given the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed herein, the actual implementation of the module will be understood within the scope of conventional skill of an engineer. Therefore, those skilled in the art can implement the invention as set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and not intended to limit the scope of the invention, which is determined by the full scope of the appended claims and their equivalents.

[0124] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several programs to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0125] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequential list of executable programs for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, a program execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can retrieve and execute a program from or in conjunction with such a program execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can mean any means that can contain, store, communicate, propagate, or transmit a program for use by or in conjunction with a program execution system, apparatus, or device.

[0126] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0127] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable program execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0128] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0129] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0130] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

Claims

1. An electronic skin, characterized in that, The electronic skin includes: a sensing platform and several sensing units disposed on the sensing platform; The sensing platform is an island bridge structure, comprising a first material and a second material, wherein the first material is a stretchable material and the second material is a non-stretchable material; the sensing platform is formed by bonding the second material to the first material after silanization treatment; the sensing unit is disposed on the second material. The sensing unit includes a sensitive film and electrodes, and the sensing unit is used to measure temperature, humidity or oxygen. The first material includes PDMS, the second material includes PET, and the sensitive film includes a PAM / Carr-LiBr hydrogel film; The second material is prepared by bonding it to the first material after undergoing silanization treatment, specifically including: The PET surface is functionalized by grafting functionalized silane; the PET and PDMS are subjected to air plasma treatment, and hydroxyl groups are introduced on the surfaces of the PET and PDMS. Then, Dragon skin prepolymer is used to bond the PET and PDMS together so that covalent siloxane bonds are formed between the Dragon skin prepolymer and the PET and PDMS.

2. The electronic skin according to claim 1, characterized in that, The sensing platform has a three-layer structure. The first layer is used to measure humidity and oxygen in the air, the second layer is used to measure the body temperature of the object, and the third layer is used to measure the humidity and TcPO2 concentration of the skin surface when in contact with the object's skin surface.

3. A method for implementing electronic skin, characterized in that, The method is used to prepare electronic skin as described in any one of claims 1 to 2, the method comprising: Take several metal sheets and prepare a first material thin film on the metal sheets as a substrate; The cut second material film was subjected to silanization treatment to obtain several islands; The islands are bonded to the substrate, and electrodes are fixed on each island and covered with a sensitive film to obtain the electronic skin; The second material film after being cut is subjected to silanization treatment to obtain several islands, including: The surface of the second material film was cleaned with deionized water and isopropanol, and then subjected to air plasma treatment for a first duration. The treated second material film is immersed in APTES solution and heated at a first temperature for a second duration to perform silanization treatment. The second material film was removed, rinsed with deionized water, and dried with a nitrogen gun to obtain several islands. The process of bonding the island to the substrate includes: The surfaces of the first material film and the silanized second material film are subjected to air plasma treatment for a third duration. The first material film and the second material film, after being bonded together with Dragon Skin prepolymer, are cured at a second temperature for a fourth duration to obtain a sensing platform.

4. The method for implementing electronic skin according to claim 3, characterized in that, The sensitive film includes a PAM / Carr-LiBr hydrogel film, which is prepared by the following steps: Weigh out acrylamide, carrageenan, N-methylenebisacrylamide, potassium chloride, photoinitiator and deionized water in a predetermined ratio, heat in an oil bath at a third temperature for a fifth time to obtain a precursor solution; PDMS prepolymer was prepared by spin-coating the PDMS prepolymer onto an aluminum sheet at a preset rotation speed. After curing, the PDMS surface was subjected to plasma treatment for a duration of six hours. The precursor solution was dropped onto plasma-treated PDMS and then spin-coated to obtain a thin precursor layer. After the precursor thin film was cryogenically treated, LiBr solution was drop-coated onto the surface of the precursor thin film and placed under a UV lamp for photoinitiation to obtain a PAM / Carr-LiBr hydrogel film.

5. The method for implementing electronic skin according to claim 3, characterized in that, The sensitive film includes an ion gel film, which is prepared by the following steps: Preparation of ion gel precursor solution using acetone; The ion gel precursor solution was poured onto an aluminum substrate and kept for seven hours until the solvent completely evaporated to obtain the ion gel.

6. The method for implementing electronic skin according to claim 3, characterized in that, The electronic skin is measured through the following steps: The first temperature, first humidity, and first oxygen level are measured using the electronic skin. The first temperature is determined to be the temperature measurement result. Based on the temperature measurement result, the first humidity is decoupled to obtain the humidity measurement result. The first oxygen is decoupled based on the temperature measurement result and the humidity measurement result to obtain the oxygen measurement result.

7. A physiological signal monitoring system, characterized in that, include: The electronic skin, control module, and wireless module as described in any one of claims 1 to 2; The control module is used to send control signals to enable the electronic skin to measure temperature, humidity or oxygen, obtain measurement signals, process the measurement signals, and send the processed measurement signals to the target terminal through the wireless module.

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