Flexible vital signs monitoring system, monitoring method and tumor radiotherapy system

Abstract

The present invention discloses a flexible vital sign monitoring system. The system comprises: a flexible substrate, a flexible circuit arranged on the flexible substrate, a sensor module and a wireless communication module; the sensor module is used to collect sensor information; the sensor module comprises at least two of a flexible humidity sensor, a flexible pressure sensor, a flexible temperature sensor and a flexible air flow sensor; the sensor information comprises: at least two of the humidity information on the surface of human skin collected by the flexible humidity sensor, the pressure information on the surface of human skin collected by the flexible pressure sensor, the temperature information on the surface of human skin collected by the flexible temperature sensor and the airflow information under the nose of the human body collected by the flexible air flow sensor. The wireless communication module is used to transmit the sensor information to a remote monitoring terminal. Any flexible sensor in the sensor module is electrically connected to the wireless communication module through a flexible circuit. The flexible vital sign monitoring system provided by the present invention is comfortable to wear, has a good user experience, and is simple and easy to operate.

Description

Technical Field

[0001] The present invention relates to the field of vital sign monitoring, and in particular to a flexible vital sign monitoring system, a monitoring method and a tumor radiotherapy system. Background Art

[0002] Tumor radiotherapy is one of the important means of tumor treatment, and vital signs detection is required during the process of tumor radiotherapy. The existing solution for vital signs detection during tumor radiotherapy is to build a patient body model through a three-dimensional scanning instrument, monitor the changes in the patient's inhalation and exhalation contour in real time to monitor the patient's breathing, detect the heart rate through an electrocardiogram monitor, and observe the patient's condition through a real-time camera. However, the traditional solution is complicated to operate and the patient's experience is poor. Summary of the invention

[0003] The purpose of the present invention is to provide a flexible vital sign monitoring system which is simple to operate and has good user experience.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A flexible vital sign monitoring system comprises: a flexible substrate, a flexible circuit arranged on the flexible substrate, a sensor module and a wireless communication module;

[0006] The sensor module is used to collect sensor information;

[0007] The sensing module includes at least two flexible sensors, any one of which is a flexible humidity sensor, a flexible pressure sensor, a flexible temperature sensor or a flexible airflow sensor; the sensing information includes at least two of humidity information, pressure information, temperature information on the surface of human skin and airflow information under the nose of the human body; wherein the humidity information is specifically collected by the flexible humidity sensor, the pressure information is specifically collected by the flexible pressure sensor; the temperature information is specifically collected by the flexible temperature sensor; and the airflow information is specifically collected by the flexible airflow sensor;

[0008] The wireless communication module is used to transmit the sensing information to a remote monitoring terminal;

[0009] Any flexible sensor in the sensing module is electrically connected to the wireless communication module through the flexible circuit.

[0010] Optional,

[0011] The flexible circuit includes a first flexible circuit;

[0012] The flexible vital sign monitoring system also includes a processor, which is electrically connected to the sensor module through the first flexible circuit, and the processor is electrically connected to the wireless communication module.

[0013] Optional,

[0014] The sensing module includes a flexible humidity sensor, a flexible temperature sensor and a flexible airflow sensor; wherein the flexible humidity sensor and the flexible temperature sensor are arranged on one side of the flexible substrate, and the flexible airflow sensor is arranged on the other side of the flexible substrate.

[0015] Optional,

[0016] The flexible circuit further includes a second flexible circuit;

[0017] The flexible vital sign monitoring system further includes: a flexible battery, wherein the flexible battery is electrically connected to the wireless communication module, the processor, and any flexible sensor in the sensor module through the second flexible circuit.

[0018] Optionally, the flexible humidity sensor includes: an electrode and a flexible humidity sensing layer, the flexible humidity sensing layer includes: an electrospinning membrane and polydopamine and silver nanoparticles attached to the electrospinning membrane, and the electrode is attached to the surface of the flexible humidity sensing layer.

[0019] Optionally, the side of the electrospinning membrane to which the polydopamine and silver nanoparticles are attached has a first protrusion structure array.

[0020] Optionally, the flexible pressure sensor comprises, from bottom to top, a first substrate layer, a pair of microstructure electrodes, a piezoresistive layer, and a hydrophobic packaging layer;

[0021] The first substrate layer comprises a biocompatible film and a first conductive substance coated on the biocompatible film, wherein a side of the biocompatible film having the first conductive substance faces the microstructure electrode;

[0022] The microstructure electrode has a second protrusion structure array on one side facing the piezoresistive layer;

[0023] The material of the piezoresistive layer is a flexible pressure sensing material, which includes a first polymer fiber membrane, nanowires attached to the fiber surface of the first polymer fiber membrane, and a second conductive substance; the material of the nanowires is metal oxide or metal; the second conductive substance is attached to the nanowires and / or the fiber surface of the first polymer fiber membrane; the nanowires are nanowires that have been grown in situ at least twice.

[0024] Optionally, the second protrusion structure array includes multiple types of protrusion monomers, protrusion monomers belonging to the same type have the same height, and at least two types of protrusion monomers have different heights.

[0025] Optionally, the flexible temperature sensor comprises: a second substrate layer and a temperature sensing layer attached to the second substrate layer;

[0026] The temperature sensing layer comprises: a three-dimensional fiber material and a third conductive substance and a hydrophobic substance attached to the fiber surface of the three-dimensional fiber material, wherein the three-dimensional fiber material comprises a cotton sheet;

[0027] The second substrate layer includes a second polymer fiber film and interdigital electrodes grown on the second polymer fiber film, and a surface of the second substrate layer having the interdigital electrodes faces the temperature sensing layer.

[0028] Optionally, the flexible airflow sensor includes: an electrode structure, a flexible polymer fiber membrane and a flexible polymer membrane stacked together, and a conductive nanowire attached to the end surface of the flexible polymer membrane; the end surface of the flexible polymer membrane is the side of the flexible polymer membrane facing away from the flexible polymer fiber membrane; wherein the electrode structure includes a positive conductive member and a negative conductive member, and the positive conductive member and the negative conductive member are connected to the conductive nanowires on the surface of the polymer membrane.

[0029] The present invention also provides a monitoring method, which is applied to the above system, and the method comprises:

[0030] Collecting sensing information, the sensing information includes at least two of humidity information, pressure information, temperature information on the surface of human skin and airflow information under the nose of the human body; wherein the humidity information is specifically collected by a flexible humidity sensor, the pressure information is specifically collected by a flexible pressure sensor; the temperature information is specifically collected by a flexible temperature sensor; and the airflow information is specifically collected by a flexible airflow sensor;

[0031] The sensing information is transmitted to a remote monitoring terminal.

[0032] The present invention also provides a tumor radiotherapy system, comprising: a tumor radiotherapy apparatus and the above-mentioned flexible vital sign monitoring system.

[0033] According to the specific embodiment provided by the present invention, the following technical effects are disclosed: the flexible vital signs monitoring system provided by the present application includes: a flexible substrate, a flexible circuit printed on the flexible substrate, and a sensor module and a wireless communication module arranged on the flexible substrate. Among them, the sensor module is used to collect sensor information, and the sensor information includes: at least two of the humidity information, pressure information, temperature information on the surface of human skin and airflow information under the nose of the human body. The sensor module includes at least two flexible sensors, the humidity information is specifically collected by a flexible humidity sensor, the pressure information is specifically collected by a flexible pressure sensor, the temperature information is specifically collected by a flexible temperature sensor, and the airflow information is specifically collected by a flexible airflow sensor. The wireless communication module is used to transmit the sensor information to a remote monitoring terminal. Any flexible sensor in the sensor module is electrically connected to the wireless communication module through a flexible circuit. The present application uses a flexible substrate and a flexible circuit to integrate the wireless communication module and the flexible sensor together, and the various components cooperate with each other to achieve at least two measurements of human body sign parameters, body temperature (measured by a flexible temperature sensor), sweating (measured by a flexible humidity sensor), pulse (measured by a flexible pressure sensor) and respiration (measured by a flexible airflow sensor).

[0034] Moreover, since the sensors used are all flexible sensors, the circuits and flexible substrates used are also flexible, so the above vital sign monitoring system is also flexible and can be worn on the patient, and is comfortable to wear and has a good user experience. At the same time, the above vital sign parameters can be monitored by simply sticking the above flexible vital sign monitoring system on the human skin, which is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 A side view showing the positional relationship of the sensors of the flexible vital signs monitoring system in an embodiment of the present invention;

[0037] Figure 2a is a schematic diagram of the positional relationship of the sensors on the upper surface of the flexible substrate in an embodiment of the present invention, Figure 2b Schematic diagram of the positional relationship of sensors on the lower surface of the flexible substrate in an embodiment of the present invention;

[0038] Figure 3 It is a transmission principle diagram of the flexible vital signs monitoring system in an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the overall flexible humidity sensor device in an embodiment of the present invention;

[0040] Figure 5 Schematic diagram of proton hopping sites on the surface of a flexible humidity sensing material under low humidity conditions in an embodiment of the present invention;

[0041] Figure 6 Schematic diagram of proton hopping sites on the surface of a flexible humidity sensing material under high humidity conditions in an embodiment of the present invention;

[0042] Figure 7 is a specific flow chart of a method for preparing a flexible humidity sensor according to an embodiment of the present invention;

[0043] Figure 8 This is a field emission scanning electron microscope (FESEM) image of nanofibers after in-situ polymerization in an embodiment of the present invention;

[0044] Fig. 9 Specific data diagram of the current value, current change and relative current change of the flexible humidity sensor under different relative humidity in an embodiment of the present invention;

[0045] Fig.10 A graph showing the relationship between the relative current change of the flexible humidity sensor and different humidity in an embodiment of the present invention;

[0046] Fig.11 A schematic diagram of the structure of a flexible pressure sensor in an embodiment of the present invention;

[0047] Fig.12 This is a field emission scanning electron microscope (FESEM) image of the TiO2 "long wire on wire" structure in an embodiment of the present invention;

[0048] Fig.13 is a specific flow chart of a method for preparing a flexible pressure sensor in an embodiment of the present invention;

[0049] Fig.14 is a sensitivity curve diagram of the flexible pressure sensor in an embodiment of the present invention;

[0050] Fig.15 is a minimum response force curve diagram of the flexible pressure sensor in an embodiment of the present invention;

[0051] Fig.16 is a response time curve diagram of the flexible pressure sensor in an embodiment of the present invention;

[0052] Fig.17 is a stable initial resistance curve diagram of the flexible pressure sensor in an embodiment of the present invention;

[0053] Fig.18is an IV curve diagram of the flexible pressure sensor in an embodiment of the present invention;

[0054] Fig.19 is a pulse test curve diagram of the flexible pressure sensor in an embodiment of the present invention;

[0055] Fig. 20 This is a schematic diagram of the structure of a flexible temperature sensor in an embodiment of the present invention;

[0056] Fig.21 This is a field emission scanning electron microscope (FESEM) image of the electrospun P (VDF-HFP) porous film in an embodiment of the present invention;

[0057] Fig. 22 The FESEM image of the temperature sensing layer of the Cotton / rGO / CNT structure in the embodiment of the present invention and the local enlarged image of a single Cotton fiber;

[0058] Fig.23 Schematic diagram of the contact angle of Cotton / rGO / CNT structure in an embodiment of the present invention;

[0059] Fig.24 Schematic diagram of the contact angle of the electrospun P (VDF-HFP) porous film in an embodiment of the present invention;

[0060] Fig.25 A bar graph comparing the air permeability of a sealed container containing 10 grams of water in an embodiment of the present invention under four conditions: I) completely sealed with a lid, II) sealed with an ordinary cotton sheet, III) sealed with a flexible temperature sensor with a fully air-permeable structure, and IV) completely unsealed;

[0061] Fig.26 is a response curve diagram of the flexible temperature sensor to different temperatures in an embodiment of the present invention;

[0062] Fig. 27 A curve diagram of the temperature response recovery time of the flexible temperature sensor in an embodiment of the present invention;

[0063] Fig.28 is a curve diagram of the temperature response stability of the flexible temperature sensor in an embodiment of the present invention;

[0064] Fig.29 Schematic diagram of the structure of a flexible airflow sensor in an embodiment of the present invention;

[0065] Fig.30 This is a scanning electron microscope image of a laser-marked Cu template in an embodiment of the present invention;

[0066] Fig.31 is a field scanning electron microscope image of a flexible polymer film having a micro-cone structure array according to an embodiment of the present invention;

[0067] Fig.32 is a response curve diagram of the flexible airflow sensor in an embodiment of the present invention;

[0068] Fig.33 is a response / recovery time curve diagram of the flexible airflow sensor in an embodiment of the present invention;

[0069] Fig.34 4 is a minimum airflow detection limit curve diagram of the flexible airflow sensor in an embodiment of the present invention. DETAILED DESCRIPTION

[0070] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with basically the same functions and effects. For example, the first wireless communication module and the second wireless communication module are only used to distinguish different wireless communication modules, and their order is not limited. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order.

[0071] It should be noted that, in this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0072] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0073] The purpose of the present invention is to provide a flexible vital sign monitoring system which is simple to operate and has good user experience.

[0074] Exemplarily, the flexible vital signs monitoring system can be used as a part of a tumor radiotherapy system in a tumor radiotherapy scenario. In addition to the flexible vital signs monitoring system, the tumor radiotherapy system also includes equipment such as a tumor radiotherapy apparatus.

[0075] The flexible vital sign monitoring system comprises: a flexible substrate 5, a flexible circuit arranged on the flexible substrate 5, a sensor module, a wireless communication module, a processor and a flexible battery.

[0076] The sensor module is used to collect sensor information. The sensor module includes at least two flexible sensors, see Figure 1 , any flexible sensor in the sensing module is a flexible humidity sensor 1, a flexible pressure sensor 2, a flexible temperature sensor 3 or a flexible airflow sensor 4. The sensing information includes at least two of the humidity information, pressure information, temperature information on the surface of human skin and the airflow information under the nose of the human body. Among them, the humidity information is specifically collected by the flexible humidity sensor 1, the pressure information is specifically collected by the flexible pressure sensor 2; the temperature information is specifically collected by the flexible temperature sensor 3; the airflow information is specifically collected by the flexible airflow sensor 4.

[0077] It should be noted that humidity information may include specific humidity values, or may be a sensor signal (such as a voltage signal, a current signal, etc.) that characterizes or carries a humidity value. Similarly, pressure information may include specific pressure values, or may be a sensor signal that characterizes or carries a pressure value. Temperature information may include specific temperature values, or may be a sensor signal that characterizes or carries a temperature value. Airflow information may include specific airflow values, or may be a sensor signal that characterizes or carries an airflow value. The above sensor signals may be analog signals or digital signals.

[0078] It should be noted that the shape of the flexible substrate 5 can be set as required, such as a mask shape, Circular (similar to Band-Aid), round, rectangular, etc., I will not go into details here.

[0079] The pressure sensor 2 may be located at the temple, the airflow sensor 4 may be located under the nose wing, and the flexible humidity sensor 1 and the flexible temperature sensor 3 may be set at any position as long as they are in contact with the skin.

[0080] It should be noted that the types of flexible sensors are not limited to the above-mentioned flexible humidity sensors, flexible pressure sensors, flexible temperature sensors, and flexible airflow sensors. Those skilled in the art can add flexible sensors for other purposes as needed, and can also flexibly select the number of types of flexible sensors included in the sensor module, which will not be elaborated here.

[0081] The wireless communication module is used to transmit the sensing information to the remote monitoring terminal or the designated terminal / server.

[0082] The remote monitoring terminal can specifically be an industrial computer, an intelligent terminal (such as a smart phone, iPad), etc.

[0083] The above-mentioned remote monitoring terminal can also be replaced by a monitoring platform, a monitoring system, etc., as long as it can analyze and display data.

[0084] Taking the application in tumor radiotherapy system as an example, the above-mentioned remote monitoring terminal or designated terminal / server can be a component of the tumor radiotherapy system. For example, it can be a device independent of the tumor radiotherapy apparatus. Of course, it can also be deployed in the tumor radiotherapy apparatus in the form of software or hardware.

[0085] When deployed in software form, the above remote monitoring terminal or designated terminal / server can be independent software. Of course, it can also be used as a subsystem (subcomponent) of a large system (such as an operating system) to provide data analysis and display services. When deployed in a tumor radiotherapy apparatus in hardware form, the above remote monitoring terminal or designated terminal / server can be exemplarily a controller / processor.

[0086] The flexible circuit may include a first flexible circuit and a second flexible circuit. The processor 6 is electrically connected to each sensor in the sensor module through the first flexible circuit, and the processor 6 is electrically connected to the wireless communication module. The connection between the processor 6 and the wireless communication module may be connected through a flexible circuit, or may be integrated on a circuit board and connected through a PCB circuit. The flexible battery is electrically connected to the wireless communication module, the processor 6, and each flexible sensor in the sensor module through the second flexible circuit.

[0087] The processor 6 is used to aggregate the sensing information of each sensor, and may also perform simple preprocessing on this basis, such as analog-to-digital conversion. Afterwards, the processor transmits the aggregated sensing information to the remote monitoring terminal through the wireless communication module.

[0088] Flexible batteries are used to power various sensors, processors, and wireless communication modules.

[0089] In some embodiments, the above-mentioned flexible vital signs monitoring system may not include a processor, and each sensor can be directly connected to the wireless communication module, and the wireless communication module can send each sensor information directly to the remote monitoring terminal or the designated terminal / server, and the remote monitoring terminal or the designated terminal / server can perform analysis and processing.

[0090] Specifically, taking analog signals as an example, the wireless communication module converts the sensor signals output by each sensor into digital form and transmits them to the remote monitoring terminal. The remote monitoring terminal analyzes the above sensor signals to obtain the sensor information represented or carried by each sensor signal: humidity value, pressure value, temperature value and airflow value.

[0091] Of course, in other embodiments of the present invention, each sensor may also be configured with a processor, and the processor of each sensor analyzes the collected sensor signals to obtain the humidity value, pressure value, temperature value or airflow value represented or carried by it.

[0092] In other embodiments, the flexible vital signs monitoring system may not include a flexible battery, and the flexible battery may be provided separately and assembled on site when used. In this case, a third flexible circuit for leading out the positive and negative electrodes of the flexible battery may be provided on the flexible substrate, and the third flexible circuit may be a circuit printed using inkjet printing technology. When in use, the third flexible circuit may be overlapped and fixed together with the input end of the power supply circuit in the flexible vital signs monitoring system on site.

[0093] Alternatively, a power supply outside the flexible vital sign monitoring system may be connected to the input terminal using a wire. The power supply may be a flexible power supply (eg, a flexible battery) or a common power supply battery.

[0094] It should be noted that, in one example, the power supply can provide a relatively independent and constant voltage for each flexible sensor. The specific connection method may include: each flexible sensor is connected in parallel between the positive and negative poles of the flexible battery, or each flexible sensor corresponds to a flexible battery, and the flexible battery only supplies power to the corresponding flexible sensor. In this case, the sensing signal output from both ends of each flexible sensor can be a current signal. The current signal can be an analog signal or a digital signal.

[0095] Of course, in other examples, the power supply can also provide a constant current for each flexible sensor (that is, the power supply is a constant current source). In this case, the sensing signal outputted from both ends of each flexible sensor can be a voltage signal. The voltage signal can be an analog signal or a digital signal.

[0096] In another example, when the sensor is equipped with a processor, whether the power supply provides a constant current or a constant voltage, according to the relationship between voltage, current, and resistance (refer to the relationship between the three in Ohm's law or the full circuit formula), the processor can calculate its own current resistance value according to the voltage or current passing through the flexible sensor. In this case, the sensing signal output by the flexible sensor (processor) carries the calculated current resistance value, which can be in the form of a digital signal or an analog signal carrying the current resistance value.

[0097] The correspondence or conversion between the sensing signal and the sensing information will be introduced later.

[0098] In an example, see Figure 1 , Figure 2a and Figure 2b The flexible humidity sensor 1 and the flexible temperature sensor 3 are arranged on one side of the flexible substrate 5 , and the flexible airflow sensor 4 is arranged on the other side of the flexible substrate 5 .

[0099] Figure 3An exemplary application scenario of the above system is shown: in a radiology room, after the processor 6 in the above flexible vital signs monitoring system collects sensor information, the wireless communication module transmits the sensor information to the wireless gateway in the radiology room, and then the wireless gateway transmits the sensor information to the industrial computer in the technician's operating room through optical fiber (the optical fiber passes through the wall).

[0100] The flexible substrate 5 is a breathable film, and a medical PU tape may be used as an example, as long as the breathability requirement is met.

[0101] The flexible circuit can be printed on the flexible substrate 5 (eg, medical PU tape) using inkjet printing technology.

[0102] The wireless transmission module can be exemplarily a Bluetooth wireless transmission module with ESP32 as the main control. In other embodiments of the present invention, the wireless communication module can also be replaced by a wired communication module as long as the transmission of sensor information can be achieved.

[0103] An exemplary preparation process of the flexible vital signs monitoring system mainly includes the following steps:

[0104] (1) Using medical PU tape as a flexible substrate and silver nanowires as conductive ink, inkjet printing technology is used to print the wire pattern in the designed circuit (corresponding to the above-mentioned flexible circuit) onto the medical PU tape.

[0105] (2) Use photocurable conductive ink for inkjet printing to fix the sensor pins and processor pins to the corresponding positions of the flexible circuit on the PU tape. The photocurable conductive ink is used as an adhesive to enhance the adhesion between the PU tape and the sensor and processor. The photocurable conductive ink can be prepared by using acrylic acid, glycerin, and a photoinitiator as raw materials.

[0106] (3) Use low-temperature solder and / or conductive silver paste to connect the sensor pins and processor pins to the corresponding flexible circuits on the PU tape to enhance the adhesion strength between the sensor, processor and PU tape.

[0107] (4) Use ultraviolet light to irradiate the photocurable conductive ink on the PU tape to cure the photocurable ink, so that each sensor and processor can be fixed on the PU tape without falling off.

[0108] The above preparation process is described in more detail below:

[0109] a. Peel off the upper protective film of the thin film tape to expose the upper surface of the thin film tape (also called the first surface), spread the thin film tape flat on a glass substrate, and use plasma enhanced chemical vapor deposition (PECVD) to treat the surface of the thin film tape to make its surface hydrophilic for inkjet printing.

[0110] The above-mentioned film tape is a skin-friendly, breathable and low-sensitivity film tape, preferably a medical PU tape or a medical PI tape.

[0111] b. On the plasma treated upper surface, use an inkjet printer to print a conductive pattern (including part of the above-mentioned flexible circuit), and then put it in an oven at 60°C for 1-2 hours to dry the conductive ink. Use a low-viscosity polyvinyl chloride (PVC) film to attach a film to protect the upper surface.

[0112] The conductive ink is an inkjet printing ink, preferably a low-viscosity ink containing silver nanowires and carbon nanotubes.

[0113] c. Turn over the film tape, peel off the lower protective film of the film tape to expose the lower surface of the film tape (also called the second surface), treat the lower surface with PECVD, prepare the conductive pattern (including part of the above-mentioned flexible circuit) by inkjet printing, and dry it in an oven at 60°C for 1-2 hours. During this process, care should be taken to prevent the original adhesive layer of the film tape from being intact and losing its adhesive function.

[0114] The conductive pattern printed on the film tape may include, in addition to the above-mentioned flexible circuit, a via area, a sensor placement area, a processor placement area, a flexible battery placement area, etc. Of course, in a scenario where a processor is not required, the above-mentioned conductive pattern does not include a processor placement area. Similarly, in some scenarios, the above-mentioned conductive pattern does not include a flexible battery placement area.

[0115] Alternatively, after printing, in addition to the above-mentioned flexible circuit, the film tape also has a blank area, and the blank area may include a via area, a sensor placement area, a processor placement area, a flexible battery placement area, etc.

[0116] d. Punch holes in the via area, apply conductive paste on the inner surface of the hole, connect the upper and lower circuits of the film tape, and dry them in an oven at 60°C for 1-2 hours. Ensure that the upper and lower circuits are effectively connected, and check whether the corresponding circuit is connected.

[0117] e. In the area where the sensor and processor are placed, use inkjet printing to prepare a photocurable ink pattern, and apply low-temperature curing conductive adhesive to the corresponding areas of the processor pins and sensor pins. Place the processor and sensor in the corresponding area so that they are fully in contact and connected with the corresponding flexible circuit on the film tape to effectively form a conductive path. Dry in an oven at 60°C for 1-2 hours to fully cure the low-temperature curing conductive adhesive.

[0118] f. Bonding the flexible battery to the film tape: Connect the negative electrode of the flexible battery to the film tape using a low-temperature curing conductive adhesive, coat the positive electrode of the flexible battery with a sticky conductive agent, and use an insulating material to isolate the positive electrode of the flexible battery from the film tape to avoid discharge during non-use. When in use, separate the insulating material from the positive electrode to allow the conductive area of ​​the film tape to be fully combined with the positive electrode of the flexible battery. Among them, the insulating material can be exemplarily an insulating tape.

[0119] The above-mentioned flexible battery is a thin-film microbattery, preferably a paper battery or a zinc-based thin-film battery.

[0120] The following is a detailed introduction to each of the above sensors:

[0121] 1. Flexible humidity sensor

[0122] See also Figure 4 The flexible humidity sensor comprises: an electrode 15 and a flexible humidity sensing layer 17, wherein the electrode 15 is attached to the surface of the flexible humidity sensing layer 17, and the flexible humidity sensing layer 17 comprises: an electrospinning membrane and polydopamine 13 and silver nanoparticles 12 attached to the electrospinning membrane.

[0123] The thickness of the flexible humidity sensing layer 17 is exemplarily in the range of 85 micrometers.

[0124] The shape of the flexible humidity sensing layer 17 can be square, circular, etc. Those skilled in the art can flexibly design its shape according to needs, which will not be described in detail here.

[0125] The silver nanoparticles 12 are used to form a conductive path, and the polydopamine 13 can provide different numbers of proton hopping sites according to the humidity, so that the conductive properties of the flexible humidity sensing material are different at different humidity. At the same time, the electrospinning membrane can be worn comfortably on the skin and fit the skin. Therefore, a flexible humidity sensor can be prepared using a flexible humidity sensing material, and the humidity can be detected based on the conductive properties and humidity sensitivity of the flexible humidity sensing material, so that it can be used in the detection scenario of the amount of sweat on human skin.

[0126] In one example, in order to increase the moisture volatilization performance of the humidity sensing material and improve the detection recovery time and detection frequency of the humidity sensing material, the electrospinning membrane has a first protrusion structure array on at least one surface, and the first protrusion structure array can be a micro-cone structure array, which can increase the contact area to achieve timely volatilization of moisture.

[0127] Specifically, the electrospun membrane includes a plurality of PVP / SA / DA composite nanofibers 11 , and polydopamine 13 and silver nanoparticles 12 are attached to the PVP / SA / DA composite nanofibers 11 .

[0128] See also Figure 5 and Figure 6 A portion of the PVP / SA / DA composite nanofiber 11 is wrapped by polydopamine 13 for detecting different humidity levels, and the remaining portion is covered by silver nanoparticles 12 for forming a conductive path.

[0129] When the relative humidity is low, protons transfer charges between polydopamine 13 molecules through a hopping mechanism: PDA polymers (polymers formed by DA) have more hydroxyl and amino groups, which can act as proton donors and receptors. Increasing relative humidity can provide more sites for proton hopping and increase conductivity.

[0130] Under high humidity conditions, protons are transferred through the Grotthuss mechanism: polydopamine 3 captures a large number of water molecules to form hydrogen bond chains or hydrogen bond networks to transfer protons. The increase in humidity causes the hydrogen bond chains to become longer and the hydrogen bond network to be more complete, so the sensor conductivity is higher. It can be seen that the above-mentioned flexible humidity sensing material has different conductive properties at different humidity levels, based on which the humidity detection is achieved.

[0131] In one example, the electrode 15 is attached to one side of the flexible humidity sensing layer 17 having a first protrusion structure array (such as a micro-cone structure array). When the flexible humidity sensor is worn on a human body, the side of the flexible humidity sensing layer 17 having the first protrusion structure array faces outward. The setting of the first protrusion structure array is conducive to the timely volatilization of moisture in the flexible humidity sensor to the outside, thereby shortening the recovery time of the flexible humidity sensor and increasing the detection frequency of the flexible humidity sensor.

[0132] In one example, the flexible humidity sensor further includes an encapsulation layer 18, which is attached to one side of the flexible humidity sensing layer 17 having the electrode 15. The encapsulation layer 18 not only fixes and protects the electrode 15, but also effectively prevents external interference with the detection. The material of the encapsulation layer 18 is preferably a hydrophobic material.

[0133] The encapsulation layer 18 may only encapsulate the electrodes 15 , or may completely cover the side of the flexible humidity sensing layer 17 having the electrodes 15 .

[0134] The material of the electrode can be conductive tape, aluminum electrode, or copper electrode.

[0135] The electrodes include positive and negative electrodes, and each electrode is connected to a wire to output current.

[0136] See also Figure 7 In one example, the preparation method of the flexible humidity sensor is as follows:

[0137] 1) A micro-cone structure Cu template was prepared using a cold light laser marking machine. The bottom diameter of the micro-cone structure was 15-20 μm and the height was 30-40 μm.

[0138] 2) Dissolve polyvinyl pyrrolidone (PVP) in deionized water and stir for 2 hours at room temperature to obtain a 3 wt% PVP solution. This is to increase the viscosity of the solution for easier electrospinning.

[0139] 3) Add sodium alginate (SA) powder and dopamine (DA) powder to the PVP solution, stir and dissolve them at room temperature, and the concentration of the resulting solution is 3wt% PVP, 1.5wt% SA and 0.5wt% DA solution. Electrospinning is performed at 19kV for one hour. The distance between the electrode and the collecting paper is 15cm, the needle flow rate is 0.8mL / h, and the collection tube speed is 200r / min. By comparison, the nanofibers obtained by this concentration ratio are more uniform and have a smaller average diameter.

[0140] 4) The electrospun membrane was reversely attached to a new collection paper, and the back side with microstructured fibers was further electrospun for 4 h to increase the thickness of the electrospun membrane and expand the sensing volume. The microstructure of the outer layer of the electrospun membrane can greatly expand the surface area, accelerate the diffusion rate of water outward, and increase air permeability.

[0141] 5) Prepare DA buffer solution, add 20 mg DA powder into 10 ml Tris-HCl buffer solution (pH = 8.5), and stir for two hours until fully dissolved. Immerse the electrospun film obtained in 4) in the DA buffer solution and stir at 30°C for 6 hours. A PDA coating is formed on a portion of the surface of the PVP / SA / DA composite nanofibers through in situ self-polymerization of DA. The in situ self-polymerization time can be long or short, but in order to control the formation of the PDA coating only on a portion of the fiber surface, and perform other operations on the remaining fiber surface, the in situ self-polymerization time should not be too long. After experiments, it was found that 6 hours was the best; the field emission scanning electron microscope (FESEM) image of the nanofibers after in situ polymerization is as follows Figure 8 shown.

[0142] 6) The nanofibers in 5) are immersed in a 30wt% silver nitrate aqueous solution, and then the obtained nanofibers are taken out and washed with deionized water. Because the carboxyl groups in alginate are easily combined with silver ions, the sodium alginate and silver nitrate on the surface of the uncovered part of the fiber undergo a replacement reaction to generate silver alginate. Because the reaction occurs after the nanofibers are immersed in the silver nitrate aqueous solution, the sodium alginate inside the fiber is also replaced by silver alginate, greatly increasing the area of ​​the sensing layer. Silver alginate is insoluble in water and will not be washed away by deionized water.

[0143] 7) Immerse the nanofibers in 6) in a 0.08% DMAB (dimethylamine borane) solution and react for 30 minutes. The reduction time can also be long or short. In order to ensure that the silver nanoparticles are covered on the fiber surface as much as possible to form a conductive path, appropriately increasing the reduction time can increase the number and size of the silver nanoparticles and improve the conductivity.

[0144] 8) The composite nanofibers were taken out, washed and dried in a nitrogen atmosphere for 6 hours to obtain the final PVP / PDA / AgNanoparticles nanofibers. Narrow silver electrodes were attached to both ends of the microstructured side of the fiber.

[0145] 9) PDMS (polydimethylsiloxane) and curing agent are fully stirred at a ratio of 10:1 for 20-60 minutes, placed in a vacuum drying oven for defoaming treatment for 30-60 minutes, and cured at 80-120°C for 1-3 hours.

[0146] It is then cut into appropriate sizes and attached to the surface of the fiber with electrodes as a flexible packaging layer, which not only protects the electrodes but also prevents external interference with the detection.

[0147] The material of the electrospinning film in the embodiment of the present invention is not limited to PVP material, but can also be the following materials: acrylonitrile-butadiene-styrene copolymer (ABS), polyurethane (PU), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), polytetrafluoroethylene (PTFE), poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)), polyacrylonitrile (PAN), polyketone (PK), polylactic acid (PLA), silk fibroin, L-lactic acid (PLLA), polyvinyl butyral (PVB), polycaprolactone (PCL).

[0148] The material of the flexible encapsulation layer in the embodiment of the present invention is not limited to the PDMS material, but can also be the following materials: polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), polyurethane (PU), thermoplastic polyurethane elastomer rubber (TPU), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN).

[0149] The material of the electrode in the embodiment of the present invention is not limited to silver, but may also be the following materials: conductive tape, aluminum electrode, copper electrode.

[0150] A 1V voltage was applied to the two electrodes of the flexible humidity sensor prepared by the above preparation method to form a loop. The current in the loop was measured, and the results were as follows: Fig. 9 and Fig.10 shown.

[0151] Fig. 9 The current value, current change and relative current change in the circuit under different relative humidity are shown. It can be seen that as the humidity increases, the current value also increases. Fig.10 shows the change of relative current with different humidity, Fig.10 It can be seen that with the increase of humidity, the relative current change increases linearly. Specifically, when the relative current change (ΔI / I0, i.e. y, ΔI=I-I0, I0 represents the current measured when the relative humidity is 15%, and I represents the change with humidity) is in the range of 0-600, the linear relationship between humidity (RH%, i.e. x) and relative current (ΔI / I0, i.e. y) can be characterized by two curves representing the relative current change. Based on this, the calibration between the relative current change and the humidity can be realized, and then the detected humidity can be determined by the relative current change.

[0152] 2. Flexible pressure sensor

[0153] See also Fig.11 The flexible pressure sensor includes, from bottom to top, a first substrate layer, a pair of microstructure electrodes 25, a piezoresistive layer, and a hydrophobic encapsulation layer 21. The first substrate layer is used to provide initial resistance. The piezoresistive layer changes its conductive properties and contact resistance with the pair of microstructure electrodes 25 according to the pressure applied thereon. The microstructure electrodes 25 are located between the first substrate layer and the piezoresistive layer. The resistance of the contact resistance connected in series with the piezoresistive layer and in parallel with the first substrate layer can be measured through the microstructure electrodes 25.

[0154] The piezoresistive layer includes a first polymer fiber film 22, nanowires 24 attached to the fiber surface of the first polymer fiber film 22, and a second conductive material 23. The nanowires 24 are made of metal oxide or metal, and the second conductive material 23 is attached to the nanowires 24 and / or the fiber surface of the first polymer fiber film 22.

[0155] The nanowires 24 are used to provide carriers for the second conductive material 23 .

[0156] The larger the specific surface area of ​​the second conductive material 23 is, the stronger the conductive property of the flexible pressure sensing material is. The specific surface area of ​​the second conductive material 23 attached thereto can be enlarged by enlarging the specific surface area of ​​the nanowires 24 .

[0157] In order to increase the specific surface area of ​​the nanowire 24, in one example, the nanowire 24 is a nanowire grown in situ at least twice. The growth of the nanowire 24 can be achieved by a hydrothermal method.

[0158] Specifically, taking the growth of TiO2 nanowires as an example, TiO2 nanowires are grown on electrospun PVDF fibers by a hydrothermal method. In order to further expand the specific surface area, TiO2 nanowires are grown again on the TiO2 nanowires (referred to as "on-line long wire structures"). Fig.12 As shown, the line length is approximately 2 microns).

[0159] The above-mentioned long-line-on-line structure can expand the specific surface area of ​​the second conductive material 23, thereby enhancing the conductive performance of the flexible pressure sensing material.

[0160] The principle of different conductive properties of the above-mentioned flexible pressure sensing materials under different pressures is as follows:

[0161] After being compressed, the contact area between the pair of microstructure electrodes 25 and the piezoresistive layer increases, and the nanowires 24 gather under the pressure, and the second conductive material 23 thereon also gathers accordingly, thereby improving the conductive performance. Moreover, according to the different pressures, the contact area between the pair of microstructure electrodes 25 and the piezoresistive layer is different, and the aggregation degree of the nanowires 24 is different, and the aggregation degree of the second conductive material thereon is also different, which leads to different conductive properties of the flexible pressure sensing material. Therefore, the above-mentioned flexible pressure sensing material has the performance of piezoresistive sensing, and based on the above-mentioned principle, the above-mentioned flexible pressure sensing material can be used to measure pressure.

[0162] The first substrate layer includes a biocompatible film 28 and a first conductive material 27 coated on the biocompatible film 28, and the side of the first substrate layer coated with the first conductive material 27 faces the microstructure electrode 25. The side of the microstructure electrode 25 facing the piezoresistive layer has a second protrusion structure array. The above electrodes are connected to the wire 26 to output current.

[0163] The thickness range of the piezoresistive layer is 50-100 um, the thickness range of the first substrate layer is 50-100 um, the thickness range of the microstructure electrode is 40-120 um, and the thickness range of the hydrophobic encapsulation layer is 100-500 um.

[0164] The shape of the piezoresistive layer can be circular, elliptical, square, etc. Those skilled in the art can flexibly design its shape according to needs, which will not be elaborated here.

[0165] The setting of the above-mentioned second protruding structure array plays a role in stress concentration, thereby increasing the sensitivity of the flexible pressure sensor: when pressure acts on the flexible pressure sensor, the above-mentioned protruding structure array contacts the piezoresistive layer, the stress of the piezoresistive layer is concentrated at the position where it contacts the micro-cone, the degree of aggregation of the nanowires 24 at the corresponding position of the piezoresistive layer is high, and the degree of aggregation of the conductive material on the nanowires 24 is also high, thereby increasing the conductive performance and providing sensitivity.

[0166] In one example, the second protrusion structure array includes multiple types of protrusion monomers, each type includes multiple protrusion monomers, and the protrusion monomers belonging to the same type have the same height, wherein at least two types of protrusion monomers have different heights.

[0167] The above-mentioned protrusion monomer can be exemplarily a micro-cone monomer. Fig.11 For example, the microstructure electrode 25 shown in the figure has two types of microcone monomers, which are arranged alternately and have different heights. Among them, the bottom diameter of the larger type of microcone is 40-80um, and the height is 80-120um, and the bottom diameter of the smaller type of microcone is 20-60um, and the height is 40-80um. Those skilled in the art can flexibly design the height of the protruding monomer, as long as it is in the lowest position when the pressure applied to the pressure sensor is satisfied, and the protruding structure monomer does not penetrate the piezoresistive layer.

[0168] The following is for Fig.11 To further explain, when a small pressure acts on the flexible pressure sensor, the larger micro-cones contact the piezoresistive layer. When the pressure increases, the smaller micro-cones may also contact the piezoresistive layer. When the pressure reaches a certain level, the flat part of the microstructure electrode 25 will contact the piezoresistive layer.

[0169] See also Fig.14 ,According to the process of the pressure applied to the flexible pressure sensor changing from small to large, the change rate of the current in the flexible pressure sensor measurement circuit can be divided into three parts. The first part has a sensitivity S1 of 281591.8 when the pressure range is 0.002-1.165kPa, the second part has a sensitivity S2 of 19686.7 when the pressure range is 1.165kPa-8kPa, and the second part has a sensitivity S3 of 1261.7 when the pressure range is 8kPa-60kPa. The above sensitivities are Fig.14 The slope of the middle curve, Fig.14 In the figure, I0 represents the current measured when there is no pressure; I represents the current measured when there is pressure, ΔI=I-I0.

[0170] The first conductive material 27 in the first substrate layer is exemplarily silver nanowires, and the resistance of the first substrate layer is in the megohm level, which is different from the resistance of the piezoresistive layer. The main function of the first substrate layer is to provide a stable initial resistance: when there is no external pressure stimulation, the microstructure electrode 25 is mainly in contact with the first substrate layer, and there are few current paths, so there is a relatively large initial resistance; because the resistance of the bottom layer remains unchanged, a relatively stable initial resistance is provided. When subjected to external stimulation, the contact area between the piezoresistive layer and the microstructure electrode 25 increases, and the conductive path increases rapidly; the microstructure electrode 25 is connected in parallel with the upper and lower layers (piezoresistive layer and first substrate layer), and the resistance is close to the small resistance, so that the resistance value measured by the device decreases. When the external force is removed, the piezoresistive layer returns to its initial state, and the resistance returns to the initial resistance value.

[0171] In one example, a third protrusion structure array is provided on one side of the hydrophobic encapsulation layer 21 facing the piezoresistive layer. The heights of the protrusions in the third protrusion structure array are consistent or inconsistent, and the shapes are regular shapes such as micro-cones or cylinders, or other irregular shapes. The setting of the third protrusion structure array reduces the viscoelasticity of the hydrophobic encapsulation layer 21 material on the one hand, and plays a role in stress concentration on the other hand.

[0172] The following is an introduction to the materials of each part of the flexible pressure sensing material:

[0173] The first polymer fiber membrane 22 can be exemplarily a PVDF (polyvinylidene fluoride) fiber membrane. Of course, poly (vinylidene fluoride-trifluoroethylene) (P (VDF-TrFE)), poly (vinylidene fluoride-hexafluoropropylene) (P (VDF-HFP)), poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P (VDF-TrFE-CTFE)), lactide-caprolactone random copolymer (P (LLA-co-CL)), polyethylene glycol (PEG), polycaprolactone (PCL), polydimethylsiloxane (PDMS), polyurethane (PU), polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN), etc. can also be used.

[0174] The second conductive material 23 can be exemplarily carbon nanotubes (CNTs), and other conductive materials can also be used, such as gold nanowires (AuNWs), gold nanoparticles (AuNPs), iron nanowires (FeNWs), reduced graphene oxide (rGO), etc.

[0175] The first conductive material 27 is exemplarily silver nanowires, but may also be other conductive materials, such as poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), gold nanowires (AuNWs), gold nanoparticles (AuNPs), iron nanowires (FeNWs), reduced graphene oxide (rGO) and other conductive materials.

[0176] The material of the above-mentioned biocompatible membrane 28 is exemplarily a protein material (such as silk fibroin), but it can also be other biocompatible materials, such as sericin (SS), keratin, collagen, zein, polylactic acid (PLA), cellulose nanocrystals (CNC), cellulose, chitosan (CS), gelatin, sodium alginate (SA) and other biomass materials.

[0177] The material of the microstructure electrode 25 is exemplarily copper, but it can also be other conductive materials, such as aluminum (Al), platinum (Pt), titanium (Ti), zirconium alloy (ZirconiumAlloy), stainless steel (Stainless Steel) and other metal and alloy materials.

[0178] The preparation method of the above-mentioned flexible pressure sensor is introduced in detail below:

[0179] (1) Preparation of SF electrospinning solution and PVDF electrospinning solution:

[0180] 1) Degumming silk cocoons to obtain regenerated silk fibroin (SF), which is dissolved in a solvent to obtain a 15 wt% to 35 wt% SF solution. The solvent may be formic acid, hexafluoroisopropanol, hexafluoroacetone, etc.

[0181] 2) Dissolving the PVDF polymer in an organic solvent to obtain a uniform mixed solution with a solubility of 10wt%-20wt% as a PVDF electrospinning solution. The solvent can be any one of acetone, N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), triethyl phosphate (TEP), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF) and dimethyl sulfide (DMS).

[0182] The above-mentioned solution concentration and solution viscosity are suitable for the requirements of electrostatic spinning.

[0183] (2) Preparation of the first substrate fiber membrane:

[0184] Use an electrospinning machine and the solution prepared in the previous step to prepare a porous film, set the flow rate to 0.1ml / h-3ml / h, the voltage parameter to 18kV-30kV, the distance between the needle tip and the collecting paper to 8cm-15cm, and the rotation speed to 100rpm-400rpm;

[0185] SF membrane needs to be cross-linked to obtain a β-folded structure to obtain a water-insoluble film. The cross-linking treatment methods include alcohol solution treatment, alcohol vapor treatment and water vapor treatment.

[0186] (3) Preparation of the first substrate layer:

[0187] The diluted AgNW solution was drop-coated on the film prepared in the previous step and then dried on a hot plate at 40-60 °C for 30-60 min.

[0188] (4) Preparation of microstructured electrode 25:

[0189] A graded micro-cone structure Cu template was prepared using a cold light laser marking machine. The bottom diameter of the larger micro-cone structure was 40-80um and the height was 80-120um, while the bottom diameter of the smaller micro-cone structure was 20-60um and the height was 40-80um.

[0190] (5) Preparation of piezoresistive layer:

[0191] The electrospun film prepared by (2) was used to grow TiO2 "long wire on wire" structure.

[0192] In order to enhance the adhesion between TiO2 and the electrospun film (the first polymer fiber film 22), the following treatments may be performed:

[0193] Taking the first polymer fiber membrane prepared from PVDF polymer (referred to as PVDF first polymer fiber membrane) as an example, the PVDF first polymer fiber membrane can be immersed in dopamine (DA) and Tris-HCl buffer solution to introduce a polydopamine (PDA) layer on the PVDF surface.

[0194] Rinse the coated PVDF fiber thoroughly with deionized water to mobilize any unstable PDA.

[0195] TiO2 nanowires were deposited on PDA-coated PVDF fibers via a two-step hydrothermal procedure to immobilize TiO2 seeds and subsequently grow TiO2 nanowires, which were then grown on the TiO2 nanowires again by a hydrothermal method.

[0196] In order to make the layer have piezoresistive properties, the film is modified with a conductive material (ie, the second conductive material 23 ).

[0197] Taking the second conductive material 23 as CNT as an example, the film can be placed in a CNT dispersion with a CNT concentration of 1wt%-10wt%, and ice bath ultrasonic treatment is performed for 2h-4h, followed by drying on a hot plate at 40-60°C for 1h-2h.

[0198] (6) Preparation of hydrophobic encapsulation layer 21:

[0199] The PDMS and curing agent were fully stirred at a ratio of 5:1 (mass ratio) for 20-60 minutes, and placed in a vacuum drying oven for defoaming treatment for 30-60 minutes, then coated on the 3D printed micro-cone structure template, and cured at 80-120°C for 1-3 hours to obtain the reverse micro-cone structure PDMS secondary template after peeling.

[0200] Next, the PDMS and curing agent are fully stirred at a ratio of 10:1 (mass ratio) for 20-60 minutes, and placed in a vacuum drying oven for defoaming treatment for 30-60 minutes, and then coated on the PDMS secondary template and cured at 80-120°C for 1-3 hours. After peeling, the micro-cone structure PDMS is obtained.

[0201] (7) Assembly of flexible pressure sensor:

[0202] The prepared thin film layers and electrodes are packaged together in the order described above to form a flexible pressure sensor.

[0203] A more specific preparation method is:

[0204] (1) Preparation of SF electrospinning solution and PVDF electrospinning solution:

[0205] 1) Degumming silk cocoons to obtain regenerated silk fibroin (SF), which is dissolved in a solvent to obtain a 15 wt% to 35 wt% SF solution. The solvent may be formic acid, hexafluoroisopropanol, hexafluoroacetone, etc.

[0206] 2) Dissolving the PVDF polymer in an organic solvent to obtain a uniform mixed solution with a solubility of 10wt%-20wt% as a PVDF electrospinning solution. The solvent can be any one of acetone, N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), triethyl phosphate (TEP), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF) and dimethyl sulfide (DMS).

[0207] The above-mentioned solution concentration and solution viscosity are suitable for the requirements of electrostatic spinning.

[0208] (2) Preparation of the first substrate fiber membrane:

[0209] Use an electrospinning machine and the solution prepared in the previous step to prepare a porous film, set the flow rate to 0.1ml / h-3ml / h, the voltage parameter to 18kV-30kV, the distance between the needle tip and the collecting paper to 8cm-15cm, and the rotation speed to 100rpm-400rpm;

[0210] SF membrane needs to be cross-linked to obtain a β-folded structure to obtain a water-insoluble film. The cross-linking treatment methods include alcohol solution treatment, alcohol vapor treatment and water vapor treatment.

[0211] (3) Preparation of the first substrate layer:

[0212] The diluted AgNW solution was drop-coated on the film prepared in the previous step and then dried on a hot plate at 40-60 °C for 30-60 min.

[0213] (4) Preparation of microstructured electrode 25:

[0214] A graded micro-cone structure Cu template was prepared using a cold light laser marking machine. The bottom diameter of the larger micro-cone structure was 40-80um and the height was 80-120um, while the bottom diameter of the smaller micro-cone structure was 20-60um and the height was 40-80um.

[0215] (5) Preparation of piezoresistive layer:

[0216] The electrospun porous membrane prepared by (2) was used to grow TiO2 "long wire on wire" structure.

[0217] In order to enhance the adhesion between TiO2 and the electrospun film, a polydopamine (PDA) layer was introduced on the PVDF-surface by immersing the fiber in a dopamine (DA) and Tris-HCl buffer solution. The coated PVDF fiber was thoroughly rinsed with deionized water to move any unstable PDA. TiO2 nanowires were deposited on the PDA-coated PVDF fiber by a two-step hydrothermal procedure to fix the TiO2 seeds and subsequently grow the TiO2 nanowires. Next, TiO2 nanowires were grown on the TiO2 nanowires again by a hydrothermal method.

[0218] In order to give the layer piezoresistive properties, the film is modified with conductive substances.

[0219] The film was placed in a CNT dispersion with a CNT concentration of 1 wt% to 10 wt%, and ice bath ultrasound was used for 2 h to 4 h, followed by drying on a hot plate at 40 to 60° C. for 1 h to 2 h.

[0220] (6) Preparation of encapsulation layer:

[0221] The PDMS and curing agent were fully stirred at a ratio of 5:1 (mass ratio) for 20-60 minutes, and placed in a vacuum drying oven for defoaming treatment for 30-60 minutes, then coated on the 3D printed micro-cone structure template, and cured at 80-120°C for 1-3 hours to obtain the reverse micro-cone structure PDMS secondary template after peeling.

[0222] Next, the PDMS and curing agent are fully stirred at a ratio of 10:1 (mass ratio) for 20-60 minutes, and placed in a vacuum drying oven for defoaming treatment for 30-60 minutes, and then coated on the PDMS secondary template and cured at 80-120°C for 1-3 hours. After peeling, the micro-cone structure PDMS is obtained.

[0223] (7) Assembly of flexible pressure sensor:

[0224] The above-mentioned film and electrodes are packaged together in the order described above to form a flexible pressure sensor.

[0225] See also Fig.13 , the following is a more specific operation method of the above steps (the most detailed preparation method of the flexible pressure sensor):

[0226] (1) Preparation of electrospinning solution:

[0227] The silk cocoons were cleaned and cut into small pieces, boiled in a 0.5wt% sodium carbonate solution for 60 min to remove sericin, then rinsed three times with deionized water and dried to obtain degummed silk fibroin fibers. SF was dissolved in a 9.3M lithium bromide (LiBr) salt solution for 2 h, and then the SF-LiBr solution was dialyzed with deionized water in a dialysis box for 72 h to remove salt. Finally, freeze-dried for 48 h to obtain regenerated SF. The regenerated SF was dissolved in 98% formic acid to obtain a 30wt% SF solution;

[0228] PVDF polymer was dissolved in a mixture of DMF and acetone (6:4) and magnetically stirred for 1 h. The solubility of the resulting solution was 10 wt%.

[0229] (2) Preparation of the first substrate fiber membrane:

[0230] Transfer the SF solution prepared in the previous step into a 5 ml syringe with a 23G needle, adjust the flow rate to 1 ml / h, set the distance between the needle tip and the collector to 15 cm, apply a voltage of 28 KV, rotate at 200 rpm, and spin for half an hour; immerse the SF-containing nanofiber membrane in a methanol solution for one hour and then dry it at 100 °C.

[0231] The PVDF solution prepared in the previous step was transferred to a 5 ml syringe with a 23G needle, the flow rate was adjusted to 0.8 ml / h, the distance between the needle tip and the collector was set to 15 cm, the applied voltage was 25 KV, and the rotation speed was 200 rpm.

[0232] (3) Preparation of the first substrate fiber membrane:

[0233] The AgNW ethanol solution was diluted in a ratio of 1:10 (volume ratio) and ultrasonicated for 30 minutes; the diluted AgNW solution was drop-coated on the SF film prepared in the previous step with a drop-coating amount of 0.5 ml, and then dried on a hot plate at 50°C for 30 minutes. The resistance value of this film was controlled at 100 megohms.

[0234] (4) Preparation of microstructured electrode 25:

[0235] A graded micro-cone structure Cu template was prepared using a cold light laser marking machine. The bottom diameter of the larger micro-cone structure was 60um and the height was 120um, while the bottom diameter of the smaller micro-cone structure was 40um and the height was 60um.

[0236] (5) Preparation of piezoresistive layer:

[0237] The electrospun porous membrane prepared in step (2) was immersed in a 10 mM L-1 Tris-HCl buffer solution with a DA (dopamine) concentration of 2 mg mL-1 and reacted for 6 h at a pH of 8.5 to cover the PVDF surface with a PDA layer. The coated PVDF fiber was thoroughly rinsed with deionized water to remove any unstable PDA.

[0238] TiO2 nanowires were grown on PVDF fibers with PDA coating by a two-step hydrothermal method. First, deionized water, acetic acid, and ethanol were mixed in a volume ratio of 1:50:150, and 1 vol% Ti(n-OBu)4 was used as a precursor to synthesize a TiO2 sol-gel solution. Next, the prepared PDA-coated PVDF fibers and the TiO2 sol-gel solution were placed in a Teflon autoclave and hydrothermally reacted at 110°C for 4 hours to obtain TiO2 seeds fixed on the PVDF fibers. Afterwards, it was rinsed with deionized water and dried in an oven at 60°C. Subsequently, it was placed in a mixture of Ti(n-OBu)4, deionized water, and hydrochloric acid (volume ratio of 1:30:30) for a secondary hydrothermal treatment for 12 hours to achieve the growth of TiO2 nanowires on PVDF nanofibers.

[0239] Next, it was put into the autoclave again and reacted at 80°C for 1 hour, and TiO2 nanowires were successfully grown again on the TiO2 nanowires. The solution used for the hydrothermal method in the autoclave was mixed with deionized water, hydrochloric acid, and titanium trichloride at a mass ratio of 1:10:10. After being thoroughly rinsed in deionized water, it was dried in an oven at 60°C.

[0240] The CNT dispersion liquid includes CNT and dispersant sodium dodecyl sulfate (SDS), wherein the CNT and dispersant sodium dodecyl sulfate (SDS) are dispersed in water at a mass ratio of 1:10. The concentration of the carbon nanotubes is 8 wt %, and the ice bath is ultrasonicated for 2 h.

[0241] In order to make the layer have piezoresistive properties, the film was placed in a multi-walled carbon nanotube solution, ultrasonicated in an ice-water bath for 4 h, and then dried in an oven at 60 °C for 1 h.

[0242] (6) Preparation of encapsulation layer:

[0243] PDMS and curing agent were fully stirred at a ratio of 5:1 for 30 minutes, placed in a vacuum drying oven for defoaming treatment for 30 minutes, and then coated on a 3D printed micro-cone structure template (the 3D printed template has a uniform micro-cone structure with a bottom diameter of 60um and a height of 80um), and cured at 100°C for 2 hours. The reverse micro-cone structure PDMS obtained after peeling was used as a secondary template;

[0244] PDMS and curing agent were fully stirred at a ratio of 10:1 for 30 minutes, and placed in a vacuum drying oven for defoaming treatment at a vacuum degree of -15 psi for 30 minutes (room temperature), and then coated on the inverse microcone structure PDMS template with a coating amount of 2 ml. Cured at 100°C for 2 hours, the microcone structure PDMS was obtained after peeling;

[0245] (7) Assembly of wearable tactile sensors:

[0246] According to the above description sequence, the flexible pressure sensor is assembled from bottom to top.

[0247] The following is an introduction to the performance of the flexible pressure sensor prepared using the most detailed preparation method of the flexible pressure sensor described above:

[0248] Fig.14 The data is measured when a bias voltage of 1 V is applied to the above-mentioned flexible pressure sensor. Wherein, I0 represents the current measured when no pressure is applied; I represents the current measured when pressure is applied, and ΔI=I-I0.

[0249] Fig.14Display: When the sensitivity (ΔI / I0, i.e. y) is in the range of 0-6*10^5, the relationship between sensitivity and pressure can be divided into three stages (parts): in the first part, when the pressure range is 0.002-1.165kPa, the sensitivity S1 is 281591.8, in the second part, when the pressure range is 1.165kPa-8kPa, the sensitivity S2 is 19686.7, and in the second part, when the pressure range is 8kPa-60kPa, the sensitivity S3 is 1261.7.

[0250] Based on this, the calibration between the current change ΔI / I0 and the pressure can be achieved, and then the pressure value can be determined by detecting the current.

[0251] The following is the reason why the lower limit of pressure is 0.002KPa (that is, 2Pa): a bias voltage of 1V is applied between the two electrodes of the above-mentioned flexible pressure sensor (size is 1cm×1cm), and a certain pressure is applied thereon (specifically, it can be achieved by placing a pressure-calibrated paper on the flexible pressure sensor). When the applied pressure is less than 2Pa, the current value output by the flexible pressure sensor does not change. When the applied pressure is 2Pa, the current value output by the flexible pressure sensor changes, and when the pressure is removed, the current value output by the flexible pressure sensor returns to the state when it is not under pressure. The specific current changes are as follows: Fig.15 As shown. It can be seen that the minimum response pressure of the flexible pressure sensor is 2Pa, and it is very sensitive to pressure.

[0252] Fig.16 The response time and recovery time of the flexible pressure sensor are shown. A bias voltage of 1V is applied between the two electrodes of the flexible pressure sensor (size 1cm×1cm), and a pressure of 255Pa is applied thereon. The change of the output current of the flexible pressure sensor is shown in Fig.16 The curve in the dashed box on the left side of the lower half ( Fig.16 The curve in the upper left corner is an enlarged view. When the pressure is removed, the output current of the flexible pressure sensor changes as shown in Fig.10 The lower part is composed of the curve in the dotted box on the side ( Fig.16 The curve graph in the upper right corner is an enlarged view thereof. It can be seen that the response time and recovery time of the above-mentioned flexible pressure sensor are 20ms, and the response is very fast.

[0253] Fig.17 This is the resistance value measured by an ohmmeter when the flexible pressure sensor (size: 1 cm×1 cm) is not subjected to external pressure. The graph shows that the flexible pressure sensor has a stable initial resistance.

[0254] Fig.18 The volt-ampere characteristic curve (IV curve) of the flexible pressure sensor is shown in FIG. Fig.18 It can be seen that under a certain pressure, the resistance of the above-mentioned flexible pressure sensor (size is 1cm×1cm) is constant, which conforms to Ohm's law.

[0255] Fig.19 The flexible pressure sensor is placed on the wrist of a young male volunteer, and the pulse waveform is measured before and after exercise. It can be seen that the pulse amplitude and frequency increase after exercise, which is consistent with the typical physiological signals before and after exercise. Fig.19 It can be seen that the above-mentioned flexible pressure sensor can be used for monitoring the pressure at the temple and the pulse. Similarly, it can also be used for monitoring the pressure at the neck, ankle and other parts.

[0256] It should be noted that the concentration of hydrochloric acid involved in each preparation example of the flexible pressure sensor is 0.1 mol / L.

[0257] In other embodiments of the present invention, the third protrusion structure array on the microstructure electrode 25 in all the above embodiments can be a single microcolumn structure, a single microsphere structure, a graded microcolumn structure, a graded microsphere structure, an irregular structure, etc., in addition to the microcone structure, as long as the compressive stress of the piezoresistive layer can be increased.

[0258] In other embodiments of the present invention, the preparation of the microstructure electrode 25 in all the above embodiments can also adopt photolithography template method, natural template method, artificial template method, AAO template method, nanoimprint template method, etc. As long as it can be used to prepare the electrode with any microstructure mentioned above.

[0259] The flexible pressure sensor provided by this application has the following effects:

[0260] (1) The first substrate layer film and the piezoresistive layer film were prepared using electrospinning technology. Compared with the traditional film-forming method, electrospinning can prepare films on a large scale and can effectively control the fine structure of the fiber to obtain a flexible film with hydrophobicity. It has good air permeability and improves the comfort of human body experience. It has a large body surface area ratio, which is conducive to the attachment of conductive materials and greatly improves the performance of the sensor.

[0261] (2) The electrospun SF (silk fibroin) film is drop-coated with AgNW as the bottom parallel resistor, which has a relatively stable initial resistance compared to the traditional piezoresistive sensor. And due to the biocompatibility of silk fibroin and the antibacterial property of AgNW, the sensor is more comfortable to wear and more friendly to the human body.

[0262] (3) The "long wire on wire" structure of (TiO2 nanowires) grown on an electrospinning membrane by a hydrothermal method has a very sensitive response to small pressure stimuli compared to traditional structures, and has a very large sensitivity within a fairly large pressure range, which meets the response monitoring of pressure intensity in different parts of the human body.

[0263] (4) The introduction of the micro-nano structure of the electrode layer and the piezoresistive layer greatly reduces the hysteresis of the sensor. The deformation under pressure and the recovery process after the pressure is removed are very rapid, which improves the response time and recovery time of the sensor.

[0264] 3. Flexible temperature sensor

[0265] See also Fig. 20 The flexible temperature sensor includes: a second substrate layer and a temperature sensing layer attached to the second substrate layer.

[0266] The second substrate layer includes a second polymer fiber film 32 and interdigital electrodes 33 grown on the second polymer fiber film 32, and the second substrate layer has a side of the interdigital electrodes 33 facing the temperature sensing layer. The interdigital electrodes 33 are connected to the wires 34 to output current.

[0267] The temperature sensing layer comprises: a three-dimensional fiber material and a third conductive material and a hydrophobic material attached to the fiber surface of the three-dimensional fiber material. The third conductive material can be carbon nanotubes, the hydrophobic material can be reduced graphene oxide, and the three-dimensional fiber material can be cotton sheets.

[0268] Among them, carbon nanotubes are attached to the fiber surface of the cotton sheet to form a conductive path in the cotton sheet structure, giving it conductive properties that traditional cotton sheet structures do not have.

[0269] Reduced graphene oxide is both hydrophobic and conductive. It is attached to the fiber surface of the cotton sheet and can form a conductive pathway in the cotton sheet structure together with carbon nanotubes.

[0270] When the temperature rises or falls, the volume of the flexible temperature sensing material will increase or decrease. Since the amount of the third conductive material is fixed, the density of the conductive path will decrease or increase accordingly, which will lead to a decrease or increase in the conductivity of the flexible temperature sensing material. In addition, the hydrophobicity of reduced graphene oxide also gives the flexible temperature sensing material hydrophobic and waterproof characteristics. Because the flexible temperature sensing material has the natural three-dimensional mesh structure of cotton sheets, the flexible temperature sensing material also has excellent air permeability.

[0271] In other embodiments of the present invention, the third conductive material may be selected from carbon nanotubes, Ag nanowires, poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANI), etc. As long as it is the third conductive material, those skilled in the art may make a flexible choice.

[0272] In addition to reduced graphene oxide, the above-mentioned hydrophobic material may also be SEBS, PFA, FEP and other hydrophobic materials, as long as the material has hydrophobic properties and does not affect conductivity, which will not be elaborated here.

[0273] In addition to cotton sheets, the above-mentioned three-dimensional fiber materials can also be selected from three-dimensional network structures such as sericin (SS), zein (Zein), polylactic acid (PLA), cellulose nanocrystals (CNC), cellulose (Cellulose), chitosan (CS), etc. Any network structure is sufficient. Different combinations of the third conductive material, hydrophobic material and three-dimensional fiber material can obtain a variety of flexible temperature sensing materials with good air permeability and not affected by sweat.

[0274] The thickness of the interdigital electrode 33 is very thin, and the thickness range may be exemplarily 100-500 nm. In this way, the interdigital electrode 33 has a certain bending property, and can bend along with the bending of the temperature sensing layer, without affecting the flexibility of the flexible temperature sensor.

[0275] The thickness of the temperature sensing layer is exemplarily in the range of 0.5 mm. The thickness of the second substrate layer is exemplarily in the range of 100 um.

[0276] The shape of the flexible temperature sensing layer 31 can be circular, oval, square, etc. Those skilled in the art can flexibly design its shape according to needs, which will not be elaborated here.

[0277] See also Fig.21 The second polymer fiber membrane 32 in the second substrate layer is a porous film and thus has the characteristic of strong air permeability.

[0278] The material used for the second polymer fiber membrane 32 in the second substrate layer can be exemplarily selected from polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP). The inherent hydrophobic and waterproof properties of the P(VDF-HFP) material give the second substrate layer hydrophobic and waterproof properties. In addition to P(VDF-HFP), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), polycaprolactone (PCL), polyimide (PI), lactide-caprolactone random copolymer (P(LLA-co-CL)), polytetrafluoroethylene (PTFE) and other materials can also be used to prepare the second polymer fiber membrane 32. In terms of preparation, a porous film can be prepared by electrospinning and other technologies. As long as the second polymer fiber membrane prepared by the material used is breathable, it will not be repeated here.

[0279] The method for forming the interdigital electrodes 33 in the second substrate layer is exemplarily generated by magnetron sputtering. Of course, other methods can also be used, such as inkjet printing, electron beam evaporation, thermal evaporation, atomic layer deposition, pulsed laser deposition, etc.

[0280] The material of the interdigital electrodes 33 can be exemplarily Ag, and can also be gold (Au), copper (Cu), aluminum (Al), titanium (Ti), tungsten (W), etc., as long as it is a ductile and flexible conductive material.

[0281] In summary, the flexible temperature sensor provided by the present application uses a three-dimensional fiber material to prepare the temperature sensing layer, and uses polymer fibers to prepare the second substrate layer. The three-dimensional fiber material and the polymer fiber are both soft and have good air permeability, and the flexible temperature sensor prepared using them also has flexibility and good air permeability, which can meet the wearer's requirements for comfort.

[0282] The preparation method of the above-mentioned flexible temperature sensor is described in detail below:

[0283] 1) GO and CNT are dissolved in a first organic solvent to prepare a GO dispersion and a CNT dispersion, respectively. The concentration of the GO dispersion is 3-12 mg / ml, and the concentration of the CNT dispersion is 0.1-0.5 mg / ml.

[0284] The first organic solvent is preferably any one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfide (DMS) and ethanol.

[0285] 2) The clean cotton is first soaked in the GO dispersion obtained in 1) for 3-6 hours, dried for 2-3 hours, and then soaked in the CNT dispersion obtained in 1) for 3-6 hours, and dried for 2-3 hours.

[0286] 3) The cotton sheet dried in 2) is placed in a vacuum drying oven. Under vacuum conditions, the thermal reduction temperature is 160° C.-240° C., and the reduction time is 2-6 h to obtain a temperature sensing layer structure of Cotton / rGO / CNT.

[0287] 4) dissolving the P(VDF-HFP) polymer in the second solvent, stirring with a magnetic force at 1000-1600 r / min for 16-24 h, and obtaining a solution with a solubility of 10 wt%-20 wt%.

[0288] The second solvent is preferably any one of acetone, N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), triethyl phosphate (TEP), methyl ethyl ketone (MEK) and dimethyl sulfide (DMS).

[0289] 5) The P(VDF-HFP) solution obtained in 4) is spun using an electrospinning process, with a spinning voltage of 15-22 kV, a feed rate of the polymer solution of 1-3 ml / h, a distance from the injection needle to the collecting paper of 12-18 cm, and the mixture is collected on the collecting paper for 2-4 hours to obtain a porous film of P(VDF-HFP).

[0290] 6) The porous film of P(VDF-HFP) obtained in 5) is placed in the cavity of a magnetron sputtering system, and Ag interdigital electrodes are magnetron sputtered on the surface of the porous film of P(VDF-HFP) with the assistance of a metal mask. The magnetron sputtering power is 60-100 W, and the sputtering time is 10-40 min, to obtain a P(VDF-HFP) second substrate layer structure with Ag interdigital electrodes.

[0291] 7) The Cotton / rGO / CNT temperature sensing layer structure obtained in 3) and the P(VDF-HFP) second substrate layer structure with Ag interdigital electrodes obtained in 6) are combined into a flexible temperature sensor.

[0292] The following are the specific operation methods of the above steps (the most detailed preparation method of flexible temperature sensor):

[0293] 1) GO and CNT were dissolved in DMF and ethanol solvents respectively to prepare GO and CNT dispersions, the concentration of GO dispersion was 9 mg / ml, and the concentration of CNT dispersion was 0.1 mg / ml.

[0294] 2) The clean cotton was first immersed in the GO dispersion obtained in 1) for 3 hours, dried for 3 hours, and then immersed in the CNT dispersion obtained in 1) for 3 hours, and dried for 3 hours.

[0295] 3) The cotton sheet dried in 2) is placed in a vacuum drying oven, and under vacuum conditions, the thermal reduction temperature is 180°C and the reduction time is 3 hours to obtain the temperature sensing layer material of Cotton / rGO / CNT. Fig. 22 It can be seen that carbon nanotubes and reduced graphene oxide are evenly wrapped on the surface of cotton fibers. Fig.23 It can be seen that the contact angle of the temperature sensing layer of the Cotton / rGO / CNT structure is 120.01°, which is much larger than 90°, proving its good hydrophobic property.

[0296] 4) The P(VDF-HFP) polymer was dissolved in acetone, and magnetic stirring was performed at 1000 r / min for 24 h. The solubility of the obtained solution was 10 wt %.

[0297] 5) The P(VDF-HFP) solution obtained in 4) was spun using an electrospinning process, with a spinning voltage of 20 kV, a feed rate of the polymer solution of 2 ml / h, a distance from the injection needle to the collecting paper of 14 cm, and the collected on the collecting paper for 4 hours to obtain a porous film of P(VDF-HFP). Fig.24 It can be seen that the contact angle of the P(VDF-HFP) porous film is 115.56°, which is greater than 90°, proving that it has good hydrophobic properties.

[0298] 6) The porous film of P(VDF-HFP) obtained in 5) is placed in the cavity of the magnetron sputtering system, and Ag interdigital electrodes are magnetron sputtered on the surface of the porous film of P(VDF-HFP) with the assistance of a metal mask. The magnetron sputtering power is 100 W, and the sputtering time is 10 min, to obtain a P(VDF-HFP) second substrate layer structure with Ag interdigital electrodes.

[0299] 7) The Cotton / rGO / CNT temperature sensing layer structure obtained in 3) and the P(VDF-HFP) second substrate layer structure with Ag interdigital electrodes obtained in 6) are combined into a flexible temperature sensor.

[0300] The resistance value of the flexible temperature sensor may change with different temperature values. The remote monitoring terminal may calculate the temperature value by table lookup or interpolation according to the calibration relationship between the resistance value and the temperature value of the flexible temperature sensor (calibration relationship table).

[0301] The interpolation method may adopt an existing method or a method foreseeable in the future, which will not be described in detail here.

[0302] Fig.25The following is a bar graph comparing the air permeability of a sealed container containing 10 grams of water in an embodiment of the present invention under four conditions: I) completely sealed with a lid, II) sealed with an ordinary cotton sheet, III) sealed with a flexible temperature sensor provided in an embodiment of the present invention, and IV) completely unsealed. This experiment is conducted by placing four sealed containers (I-IV) containing 10 grams of water at 60°C, and measuring the amount of water remaining in the four containers at 0, 8, 28, 35, and 48 hours. It can be seen that the weight of the water remaining in the container with III) the flexible temperature sensor provided in the embodiment of the present invention and the container with IV) being completely unsealed is basically the same, and the flexible temperature sensor provided in the embodiment of the present invention has good air permeability.

[0303] Fig.26 The following is a graph showing the response of the flexible temperature sensor to different temperatures using the most detailed preparation method of the flexible temperature sensor. Fig.26 As shown in the figure, as the temperature increases from 30°C to 40°C, the resistance of the flexible temperature sensor in the embodiment of the present invention increases continuously, from 3200 ohms to 7000 ohms. Based on this, the relationship between the resistance and temperature of the flexible temperature sensor can be calibrated (the calibration relationship between the two can be represented in the form of a chart or a calibration curve), and then the current temperature can be determined according to the current resistance value of the flexible temperature sensor.

[0304] Specifically, when the power supply provides a constant voltage, the processor 6 can collect the current value across the flexible temperature sensor. Since the voltage across the flexible sensor is constant, the resistance of the flexible temperature sensor can be calculated based on the constant voltage and current value, and then based on the calibration relationship between the above temperature and resistance, the temperature detected by the flexible temperature sensor can be determined.

[0305] It should be noted that the above-mentioned resistance calculation process and temperature determination process can be completed in the above-mentioned processor, or can be completed by a remote monitoring terminal or a designated terminal / server, and the processor is only responsible for collecting the current of the flexible temperature sensor.

[0306] Fig. 27 The temperature of the flexible temperature sensor is changed, and the resistance at both ends of the flexible temperature sensor is measured by using a source meter (model Keithley 2602B). Fig.26 As shown, when the temperature is increased from 31°C to 39°C, the resistance of the flexible temperature sensor in the embodiment of the present invention increases from 3500 ohms to 6400 ohms, and the response time is 20s. When the temperature is lowered to 31°C again, the resistance of the flexible temperature sensor in the embodiment of the present invention decreases from 6400 ohms to 3500 ohms, and the recovery time is 80s.

[0307] Fig.28 is a curve diagram of the temperature response stability of the flexible temperature sensor in an embodiment of the present invention. The temperature of the environment where the flexible temperature sensor is located is changed, such as Fig.28 As shown, by repeatedly raising the temperature from 31°C to 39°C and then lowering it to 31°C, it was found that the resistance value of the flexible temperature sensor could also stably increase from 3500 ohms to 6400 ohms and then decrease to 3500 ohms multiple times, indicating that the device has good stability.

[0308] The flexible temperature sensor adopted in this application has the following effects:

[0309] (1) The solution infiltration method for preparing temperature sensing materials enables the traditional cotton sheet structure to have hydrophobic, waterproof and conductive properties at the same time. The method is simple, easy to operate and low in cost.

[0310] (2) From the solution infiltration method to prepare the temperature sensing material to the P(VDF-HFP) hydrophobic and waterproof second substrate layer structure prepared by electrospinning, the entire flexible temperature sensor is not only waterproof but also fully breathable, which can meet the requirements of human skin for wearable comfort.

[0311] (3) Based on the temperature sensing material, it not only has the natural three-dimensional network structure of the traditional cotton sheet structure, but also has the conductive properties of rGO and CNT. Therefore, when the temperature of the external environment changes, the three-dimensional network structure will deform, that is, thermal expansion and contraction, resulting in the increase and decrease of the device volume. Since the volume of rGO and CNT conductive fillers is constant, as the device volume increases and decreases, the resistance value of the device will increase and decrease, thereby realizing the monitoring of the external environment temperature signal.

[0312] 4. Flexible airflow sensor

[0313] See also Fig.29 The flexible airflow sensor includes: an electrode structure, a flexible polymer fiber membrane 43 and a flexible polymer membrane 42 stacked together, and a conductive nanowire 41 attached to the end surface of the flexible polymer membrane. The end surface of the flexible polymer membrane is the side of the flexible polymer membrane 42 facing away from the flexible polymer fiber membrane 43.

[0314] The electrode structure includes a positive electrode conductive member and a negative electrode conductive member, and the positive electrode conductive member and the negative electrode conductive member are respectively connected to the conductive nanowires 41 on the surface of the polymer film.

[0315] In one example, the positive electrode conductive member may include only the positive electrode lead wire 44, and the negative electrode conductive member may include only the negative electrode lead wire 45. The positive electrode lead wire 44 and the negative electrode lead wire 45 are connected to the conductive nanowire 41 on the surface of the flexible polymer film. Specifically, the positive electrode lead wire 44 and the negative electrode lead wire 45 may be directly connected to the conductive nanowire 41 on the surface of the flexible polymer film. Fig.29 On the conductive nanowires 41 on the left and right sides. In other words, the electrode lead wires 44 and the negative electrode lead wires 45 can be respectively arranged at the edges of the flexible polymer film 42 and connected or contacted with the conductive nanowires 41 at the edges.

[0316] In another example, the positive electrode conductive member may include a positive electrode sheet and a positive electrode lead wire connected to the positive electrode sheet, and the negative electrode conductive member may include a negative electrode sheet and a negative electrode lead wire connected to the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are respectively attached to Fig.29 On the conductive nanowires 41 on the left and right sides. In other words, the positive electrode sheet and the negative electrode sheet can be respectively arranged at the edge of the flexible polymer film 42 and connected or contacted with the conductive nanowires 41 at the edge.

[0317] In one example, in order to increase the specific surface area of ​​the conductive nanowires 41, grow more conductive nanowires 41, and make the flexible airflow sensor have better sensing capability, the flexible polymer film 42 has a fourth convex structure array on one side attached with the conductive nanowires 41. The fourth convex structure array can be exemplarily a micro-cone structure array, or a cylindrical, square, etc.

[0318] The fourth protrusion structure array can increase the surface area of ​​the flexible polymer film 42 , and the conductive nanowires 41 are attached to the flexible polymer film 42 . The increase in the surface area of ​​the flexible polymer film 42 can increase the specific surface area of ​​the conductive nanowires 41 accordingly.

[0319] When the conductive nanowires 41 are stimulated by airflow, the conductive nanowires 41 will contact each other. Compared with the state when they are not stimulated by airflow, the conductive paths of the conductive nanowires 41 on the surface of the flexible polymer film 42 increase, and the resistance decreases. Moreover, the greater the airflow, the more conductive nanowires 41 contact each other, the more conductive paths there are in the conductive nanowires 41 on the surface of the flexible polymer film 42, and the smaller the resistance. Based on this, it can be seen that when the airflow size is different, the resistance size of the conductive nanowires 41 on the surface of the flexible polymer film 42 is different, and then the partial pressure of the flexible airflow sensor will be different. Therefore, the size of the airflow can be inferred by specifically measuring the voltage of the flexible airflow sensor.

[0320] In addition, when stimulated by a small airflow, the conductive nanowires 41 contact each other, thereby forming a large number of conductive paths, and their resistance is rapidly reduced; when stimulated by a large airflow, the fourth protrusion structure array on the flexible polymer film 42 will also deform, such as bending, wrinkling and changing shape. This further increases the contact area and contact number between the conductive nanowires 41, thereby realizing the detection of airflow within a large airflow intensity range.

[0321] The conductive nanowires 41 can be exemplarily gold nanowires. In addition, the conductive nanowires 41 can also be made of platinum nanowires (PtNWs), silver nanowires (AgNWs), copper nanowires (CuNWs), nickel nanowires (Ni NWs), iron nanowires (Fe NWs), polyaniline nanowires (PANINWs), metal organic framework nanowires (MOF NWs), and carbon nanotubes (CNTs).

[0322] The material of the flexible polymer film 42 can be exemplified as polyvinylidene fluoride-hexafluoropropylene. In addition, the material of the flexible polymer film 42 can also be selected from polydimethylsiloxane (PDMS), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), polyvinyl alcohol (PVA), polyurethane (PU), thermoplastic polyurethane elastomer rubber (TPU), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN).

[0323] The material of the above-mentioned flexible polymer fiber membrane can be exemplified as polyvinylidene fluoride-co-hexafluoropropylene P (VDF-HFP). In addition, the material of the flexible polymer fiber can also be selected from acrylonitrile-butadiene-styrene copolymer (ABS), polyurethane (PU), polyvinyl alcohol (PVA), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)), polyacrylonitrile (PAN), polyketone (PK), polylactic acid (PLA), silk fibroin, L-lactic acid (PLLA), polyvinyl butyral (PVB), and polycaprolactone (PCL).

[0324] Since the flexible polymer film 42, the flexible polymer fiber film 43 and the conductive nanowires 41 are all flexible, the flexible airflow sensor formed by them also has a soft characteristic. At the same time, due to the air permeability of the fiber structure, the polymer fiber film has air permeability, and the flexible airflow sensor with it as a substrate also has air permeability. The combination of softness and air permeability makes the flexible airflow sensor wearable on the human body.

[0325] The preparation method of the flexible airflow sensor is described in detail below:

[0326] Taking the preparation of a flexible polymer film using a P(VDF-HFP) solution as an example, the preparation method may specifically include the following steps:

[0327] First, the copper sheet was cleaned and a Cu template with an inverse microcone structure array was prepared using a laser marking machine.

[0328] Afterwards, the P(VDF-HFP) solution was spin-coated on the Cu template with the inverse microcone structure array and peeled off after drying to obtain a flexible polymer film with the microcone structure array.

[0329] Then, vertical gold nanowires were grown on the surface of the flexible polymer film with microcone structure arrays using a solution method.

[0330] A breathable film (i.e., a flexible polymer fiber membrane) is prepared by electrospinning a polymer solution, and the flexible polymer fiber membrane is used as a bottom substrate after being treated by plasma.

[0331] Finally, the flexible polymer fiber membrane is combined with a flexible polymer membrane with gold nanowires grown thereon, and positive and negative electrode conductive parts are respectively led out from the gold nanowires on both sides of the flexible polymer membrane to form an airflow sensor.

[0332] The template may be made of other materials besides Cu, such as Al, Fe, Ni, Ti, etc.

[0333] The following is a more detailed introduction to the preparation method of the flexible airflow sensor (the most detailed preparation method of the flexible airflow sensor):

[0334] 1) First, the substrate copper foil was ultrasonically cleaned in acetone, ethanol, and deionized water for 2 minutes respectively, and then dried with nitrogen to obtain a clean substrate.

[0335] 2) Using a cold light laser marking machine with a laser power of 5-10W and a laser scanning speed of 20-50cm / s, a Cu template with an inverse microcone structure array is prepared. The prepared microcone structure array is shown in Fig.30 The bottom diameter of the micro-cone structure is 40-80um and the height is 80-120um.

[0336] 3) P(VDF-HFP) powder is mixed with acetone and stirred under ultrasonication for 20-60 minutes to obtain a 5-15 wt % P(VDF-HFP) / acetone solution.

[0337] 4) The P(VDF-HFP) / acetone solution is drop-coated on the inverse microcone structure array Cu template with a dropper, and spin-coated at a speed of 500-1500 rpm for 400-800 s to obtain a uniformly distributed thin film with a thickness of about 500-700 um.

[0338] 5) Place the P(VDF-HFP) / Cu template in a vacuum drying oven at -90 kPa, 20-40°C for 2-5 hours to remove the acetone solution and obtain a dry film. Then, H2O2, concentrated hydrochloric acid and water are mixed in a certain ratio (volume ratio 1:1:1 or 2:2:1) to prepare a Cu template etching solution. Place the P(VDF-HFP) / Cu template in the above etching solution, react for 6-18 hours to remove the Cu template, and repeatedly wash with deionized water to obtain a complete and non-adhesive P(VDF-HFP) microcone structure array film (also referred to as a flexible polymer film with a microcone structure array), see Fig.31 .

[0339] 6) After the P(VDF-HFP) micro-cone structure array film is treated with air plasma for 2-10 minutes, it is repeatedly rinsed in ethanol and dried with N2, and then the film is placed in a suspension of AuNPs for 1-5 hours to deposit the Au seed layer on the surface of the P(VDF-HFP) film. Next, after rinsing with deionized water and drying with N2, the film is immersed in a growth solution of water / ethanol (volume ratio = 1.2:1), containing 4-mercaptobenzoic acid (1.1-2.8mM), HAuCl4 (8-16mM) and L-ascorbic acid (15-35mM). After 3-6 minutes, the P(VDF-HFP) film is taken out from the growth solution, rinsed with ethanol, and dried with N2, thereby obtaining an AuNWs / P(VDF-HFP) micro-cone structure array film (also known as a flexible polymer film with gold nanowires attached).

[0340] 7) Dissolve PCL in acetone solution to prepare a 6-12wt% PCL precursor solution, inject the prepared spinning solution into a syringe, connect the positive electrode of the high-voltage power supply to the spinning nozzle, and the negative electrode to the receiving plate (aluminum foil). The spinning voltage is 12-24kV, the receiving distance is 10-16cm, and electrospinning is performed at room temperature. The electrospinning film is obtained by spinning, and it is dried at 30-40°C for 12-24h and then used. The thickness of the film is about 600-800um. Since PCL fibers have strong hydrophobicity, in order to improve the hydrophilicity of PCL electrospun fibers, an ion treatment machine is used to treat the obtained PCL electrospun fibers with oxygen plasma for 1-2min at a power of 25-40W and 0.2-0.3mbar.

[0341] 8) The PCL electrospun film was laminated with the Au NWs / P(VDF-HFP) microcone structure array film, and Cu wires were connected to the gold nanowires on both sides of the flexible polymer film surface to obtain a flexible airflow sensor with Au NWs / P(VDF-HFP) / PDL structure.

[0342] Fig.32The following is a response curve of a flexible airflow sensor prepared using the most detailed preparation method of a flexible airflow sensor. A voltage of 1 V is applied to the flexible airflow sensor. Fig.32 As shown, as the airflow pressure increases, the current of the flexible airflow sensor also increases, and the ratio of the changing current to the initial current also increases with the increase of the airflow pressure. Fig.32 In the figure, I0 is the current of the flexible airflow sensor measured when the airflow sensor is not stimulated by airflow, which is called the initial current. ΔI is the difference between the current of the flexible airflow sensor measured under the stimulation of a certain airflow pressure and the initial current. Based on this, the relationship between the current change (the ratio of the current to the initial current) and the airflow intensity can be calibrated, and the intensity of the detected airflow can be obtained according to the detected current change (or the detected current) of the flexible airflow sensor.

[0343] Fig.33 The above flexible airflow sensor is stimulated by airflow at the 9th second. Fig.33 The time for the flexible airflow sensor to respond to airflow stimulation is about 0.5s, and after the airflow is removed, the recovery time of the flexible airflow sensor is about 0.8s. It can be seen that the flexible airflow sensor responds to the airflow and recovers to the initial state quickly.

[0344] Fig.34 The minimum airflow detection limit curve of the flexible airflow sensor is shown in Figure 2. When the flexible airflow sensor is stimulated by an airflow of less than 6 kPa, the current of the flexible airflow sensor does not change significantly. When the airflow pressure increases to 6 kPa, the current of the flexible airflow sensor changes significantly. Fig.34 As shown in FIG. 1 , it can be seen that the minimum detection airflow of the above flexible airflow sensor is 6 kPa. When the airflow of 6 kPa is intermittently used, the change of ΔI / I0 is as follows: Fig.34 As shown, Fig.34 It can be seen that the above-mentioned flexible airflow sensor responds very stably to airflow pressure of the same intensity.

[0345] It should be noted that Fig.32 , Fig.33 ,and Fig.34 All of the measurement data are obtained under the condition of applying 1V voltage to the above-mentioned flexible airflow sensor at room temperature.

[0346] The flexible airflow sensor approved by this application has the following advantages:

[0347] 1) A flexible polymer film with a protrusion structure array is prepared by a laser-marked Cu template solution infiltration method, which is low-cost, simple to prepare and can be prepared on a large area. This effectively solves the problems of long time, complex process, high cost and adhesion between polymer films in the current micro-nano processing technology.

[0348] 2) Conductive nanowires are grown on a flexible polymer film with an array of protruding structures by a solution method as a sensing layer for airflow sensing, which is simple, easy to operate and low-cost.

[0349] 3) Under weak airflow, the conductive nanowires will also deform, such as bending (which will increase the conductive path formed by the conductive nanowires and enhance the conductive performance). In other words, the flexible airflow sensor has a low detection limit.

[0350] 4) When stimulated by a small airflow, the conductive nanowires contact each other, thus forming a large number of conductive paths, which rapidly reduce their resistance; when stimulated by a large airflow, the array of protruding structures on the flexible polymer film will also deform, which further increases the contact area and number of contacts between the conductive nanowires, thereby achieving a greater sensitivity within a larger airflow detection range. At the same time, it can immediately return to its original state after the airflow is removed, and its performance remains stable after multiple uses.

[0351] 5) Electrospinning is used to prepare flexible, breathable and integrable films that can be more comfortably attached to the human body surface.

[0352] 6) Compared with traditional sensors, the flexible airflow sensor provided by the embodiment of the present invention has a simpler structure and a simpler preparation process, a lower cost, a higher sensitivity to airflow under external stimulation, a faster response, and better repeatability.

[0353] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0354] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A flexible vital signs monitoring system, characterized in that: include: A flexible substrate, a flexible circuit, a sensor module and a wireless communication module arranged on the flexible substrate; The sensor module is used to collect sensor information; The sensing module includes at least two flexible sensors, any one of which is a flexible humidity sensor, a flexible pressure sensor, a flexible temperature sensor or a flexible airflow sensor; the sensing information includes at least two of humidity information, pressure information, temperature information on the surface of human skin and airflow information under the nose of the human body; wherein the humidity information is collected by the flexible humidity sensor, the pressure information is collected by the flexible pressure sensor; the temperature information is collected by the flexible temperature sensor; and the airflow information is collected by the flexible airflow sensor; The flexible pressure sensor includes, from bottom to top, a first substrate layer, a pair of microstructure electrodes, a piezoresistive layer and a hydrophobic packaging layer; the first substrate layer includes a biocompatible film, and a first conductive substance coated on the biocompatible film, the biocompatible film has a side with the first conductive substance facing the microstructure electrode; the side of the microstructure electrode facing the piezoresistive layer has a second protrusion structure array; the material of the piezoresistive layer is a flexible pressure sensing material, the flexible pressure sensing material includes a first polymer fiber membrane, nanowires attached to the fiber surface of the first polymer fiber membrane, and a second conductive substance; the material of the nanowire is a metal oxide or a metal; the second conductive substance is attached to the nanowire and / or the fiber surface of the first polymer fiber membrane; the nanowire is a nanowire that has been in-situ grown at least twice; The wireless communication module is used to transmit the sensing information to a remote monitoring terminal; Any flexible sensor in the sensing module is electrically connected to the wireless communication module through the flexible circuit.

2. The flexible vital signs monitoring system according to claim 1, characterized in that: The flexible circuit includes a first flexible circuit; The flexible vital sign monitoring system also includes a processor, which is electrically connected to the sensor module through the first flexible circuit, and the processor is electrically connected to the wireless communication module.

3. The flexible vital signs monitoring system according to claim 1, characterized in that: The sensing module includes a flexible humidity sensor, a flexible temperature sensor and a flexible airflow sensor; wherein the flexible humidity sensor and the flexible temperature sensor are arranged on one side of the flexible substrate, and the flexible airflow sensor is arranged on the other side of the flexible substrate.

4. The flexible vital signs monitoring system according to claim 2, characterized in that: The flexible circuit further includes a second flexible circuit; The flexible vital sign monitoring system further includes: a flexible battery, and the flexible battery is electrically connected to the wireless communication module, the processor, and any flexible sensor in the sensor module through the second flexible circuit.

5. The flexible vital sign monitoring system according to any one of claims 1 to 4, characterized in that: The flexible humidity sensor comprises: an electrode and a flexible humidity sensing layer, wherein the flexible humidity sensing layer comprises: an electrospinning membrane and polydopamine and silver nanoparticles attached to the electrospinning membrane, and the electrode is attached to the surface of the flexible humidity sensing layer.

6. The flexible vital signs monitoring system according to claim 5, characterized in that: The side of the electrospinning membrane on which the polydopamine and silver nanoparticles are attached has a first protrusion structure array.

7. The flexible vital signs monitoring system according to claim 1, characterized in that: The second protrusion structure array includes multiple types of protrusion monomers. Protrusion monomers belonging to the same type have the same height, and at least two types of protrusion monomers have different heights.

8. The flexible vital sign monitoring system according to any one of claims 1 to 4, characterized in that: The flexible temperature sensor comprises: a second substrate layer and a temperature sensing layer attached to the second substrate layer; The temperature sensing layer comprises: a three-dimensional fiber material and a third conductive substance and a hydrophobic substance attached to the fiber surface of the three-dimensional fiber material, wherein the three-dimensional fiber material comprises a cotton sheet; The second substrate layer includes a second polymer fiber film and interdigital electrodes grown on the second polymer fiber film, and a surface of the second substrate layer having the interdigital electrodes faces the temperature sensing layer.

9. The flexible vital sign monitoring system according to any one of claims 1 to 4, characterized in that: The flexible airflow sensor comprises: an electrode structure, a flexible polymer fiber membrane and a flexible polymer membrane stacked together, and a conductive nanowire attached to the end surface of the flexible polymer membrane; the end surface of the flexible polymer membrane is the side of the flexible polymer membrane facing away from the flexible polymer fiber membrane; wherein the electrode structure comprises a positive conductive member and a negative conductive member, and the positive conductive member and the negative conductive member are connected to the conductive nanowires on the surface of the polymer membrane.

10. A tumor radiotherapy system, characterized in that: include: A tumor radiotherapy apparatus and a flexible vital sign monitoring system as claimed in any one of claims 1 to 9.

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