Flexible infrared thermosensitive physiological signal detector and preparation method thereof

Abstract

The application relates to a flexible infrared thermal physiological signal detector and a preparation method thereof, and belongs to the field of wearable physiological monitoring devices.The structure comprises a detector main body and a packaging layer covering the detector main body, the detector main body is used for receiving temperature changes of a sensitive unit caused by human body thermal radiation, and outputs resistance signals or thermoelectric voltage signals corresponding to the temperature changes, Te x Se 1‑x The thin film forming sensitive unit and the reference unit have good synergy in material selection, structure design and process implementation, can effectively improve the problems of the existing flexible infrared physiological signal detector in weak thermal signal detection, environmental interference suppression and flexible adaptability, and have good application prospect.

Description

Technical Field

[0001] This invention relates to a flexible infrared thermal physiological signal detector and its preparation method, belonging to the field of wearable physiological monitoring devices. Background Technology

[0002] With the development of wearable electronics and smart healthcare technologies, the demand for long-term, continuous, and low-burden monitoring of human physiological signals is constantly increasing. Compared with contact electrodes and biochemical sampling methods, infrared detection based on changes in human body thermal radiation has advantages such as being non-invasive, comfortable, and suitable for dynamic monitoring, and is particularly suitable for collecting signals related to respiration, body surface temperature, and local blood flow.

[0003] Existing infrared detectors mainly include photonic detectors and thermal detectors. Photonic detectors typically require complex material systems and fabrication processes, and some devices also require cooling conditions, making it difficult to simultaneously achieve low cost, flexibility, and large-area fabrication. Although thermal detectors can operate at room temperature, they still generally suffer from insufficient thermal isolation, large environmental temperature drift, complex structure, and poor stability in detecting weak physiological thermal signals in flexible devices.

[0004] Te-Se alloys possess advantages such as low-temperature deposition, good compatibility with flexible processes, and suitability for large-area fabrication, making them promising candidates for flexible electronic devices. However, existing Te-Se thin-film devices primarily focus on general photoelectric detection applications, and there is still room for improvement in the design of flexible thermistor structures for detecting weak thermal radiation physiological signals from the human body. Particularly in wearable applications, the lack of thermal isolation structures, reference compensation units, and well-defined sensing window designs makes it difficult to achieve stable, low-noise physiological thermal signal detection.

[0005] Therefore, it is necessary to provide a flexible infrared thermosensitive physiological signal detector based on Te-Se alloy thin film with a clear structure, feasible process, suitable for flexible integration, and capable of suppressing environmental temperature drift, as well as its fabrication method. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a flexible infrared thermal physiological signal detector and its preparation method, so as to solve the problem that existing devices are difficult to achieve stable and low-noise physiological thermal signal detection in wearable applications.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a flexible infrared thermosensitive physiological signal detector, comprising a detector body and an encapsulation layer covering the detector body. The detector body receives temperature changes in a sensitive unit caused by human thermal radiation and outputs a resistance signal or thermoelectric voltage signal corresponding to the temperature change. The detector body includes a flexible substrate, a sensitive unit disposed on the flexible substrate, and a reference unit. A thermal isolation area is disposed below the sensitive unit, and an infrared shielding layer is disposed above the reference unit to reduce the response of the reference unit to external infrared radiation. Signal output terminals are electrically connected to the sensitive unit and the reference unit, respectively. The encapsulation layer forms an infrared sensing window above the sensitive unit. Both the sensitive unit and the reference unit include Te. x Se 1-x Sensitive film, Te on the sensitive unit x Se 1-x The sensitive thin film is electrically connected to a first electrode and a second electrode. The first electrode and the second electrode are spaced apart and form a coplanar electrode structure on the same side. The Te on the reference unit x Se 1-x The sensitive thin film is electrically connected to a third electrode and a fourth electrode, which are spaced apart and form a coplanar electrode structure on the same side.

[0008] Furthermore, the thermal isolation area is a groove-filled thermal isolation area located below the sensitive unit. The groove of the groove-filled thermal isolation area is filled with a low thermal conductivity polymer or a low thermal conductivity porous polymer and is cured and planarized to form a low thermal conductivity support surface that is flush with or substantially flush with the upper surface of the flexible substrate, so that the Te x Se 1-x A sensitive thin film is deposited on the low thermal conductivity support surface.

[0009] Furthermore, the Te x Se 1-x The value of x in the sensitive film ranges from 0.4 to 0.9.

[0010] Furthermore, the Te x Se 1-x The thickness of the sensitive film is 20-300 nm, and the Te... x Se 1-x The sensitive thin film has an amorphous or polycrystalline structure.

[0011] Furthermore, the infrared sensing window is provided with an interval structure around it to maintain a predetermined gap with the human body surface, the predetermined gap being 0.1-3mm.

[0012] Furthermore, the signal output terminal includes flexible metal leads electrically connected to the first electrode, the second electrode, the third electrode, and the fourth electrode, respectively, and an edge signal output pad disposed in the edge region of the flexible substrate.

[0013] A method for fabricating the flexible infrared thermosensitive physiological signal detector includes the following steps: Step S1: Clean and pre-treat the surface of the flexible substrate; Step S2: A groove is formed in the region corresponding to the sensitive unit of the flexible substrate, a low thermal conductivity polymer or a low thermal conductivity porous polymer is filled in the groove, and a groove-filled thermal insulation area with a low thermal conductivity support surface is formed by curing and planarization. Step S3: Te is deposited on the low thermal conductivity support surface of the groove-filled thermal isolation zone and the corresponding area of ​​the reference unit using a thermal evaporation process. x Se 1-x Sensitive thin films are formed to create functional thin films in sensitive and reference cells. Step S4, in the sensitive unit Te x Se 1-x A first electrode and a second electrode are fabricated on the sensitive thin film, and the Te in the reference cell... x Se 1-x A third and fourth electrode are fabricated on a sensitive thin film, and flexible metal leads and edge signal output pads that are electrically connected to the first, second, third, and fourth electrodes are fabricated simultaneously or in steps to form coplanar electrodes on the same side and flexible signal output terminals. Step S5: An infrared shielding layer is prepared above the reference unit; Step S6: Form an encapsulation layer on the surface of the detector body and retain an infrared sensing window above the sensitive unit; Step S7: Set up an interval structure to control the gap with the human body surface to obtain a flexible infrared thermosensitive physiological signal detector.

[0014] Furthermore, after step S3 is completed, the process also includes processing the Te... x Se 1-x The sensitive film undergoes post-annealing treatment at a temperature of 60-180℃ for a time of 1-30 minutes.

[0015] Furthermore, in step S4, the first electrode, second electrode, third electrode, fourth electrode, flexible metal lead, and edge signal output pad are prepared by one or more of the following methods: thermal evaporation, electron beam evaporation, magnetron sputtering, inkjet printing, screen printing, or transfer printing.

[0016] Furthermore, in step S6, the encapsulation layer is formed by chemical vapor deposition, spin coating, spraying, blade coating, or lamination.

[0017] The beneficial effects of this invention are: By depositing Te on a flexible substrate x Se 1-x The thin film forms a sensitive unit and a reference unit. The sensitive unit receives human thermal radiation and generates a corresponding electrical response, while the reference unit characterizes changes in the environmental background. A thermal isolation zone is set below the sensitive unit to reduce thermal diffusion from the sensitive area to the substrate and laterally. An infrared shielding layer is set above the reference unit to reduce the direct response of the reference unit to human infrared radiation. An encapsulation layer is set on the surface of the detector body, and an infrared sensing window is retained above the sensitive unit so that human thermal radiation preferentially acts on the sensitive unit. This design exhibits good synergy in material selection, structural design, and process implementation, and can effectively improve the problems of existing flexible infrared physiological signal detectors in terms of weak thermal signal detection, environmental interference suppression, and flexible adaptability, showing promising application prospects. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a side view schematic diagram of a flexible infrared thermosensitive physiological signal detector according to the present invention; Figure 2 for Figure 1 Detailed structural diagram; Figure 3 This is a top view schematic diagram of the flexible infrared thermosensitive physiological signal detector of the present invention; Figure 4 A top view of the connection layout between the signal output terminal and the electrodes; Figure 5 This is a schematic diagram of the differential circuit of the sensitive unit and the reference unit, as well as the readout circuit of the controller.

[0019] In the diagram: Detector body-1, encapsulation layer-2, flexible substrate-11, sensing element-12, reference element-13, thermal isolation area-121, infrared shielding layer-131, signal output terminal-14, infrared sensing window-21, spacing structure-211, Te x Se 1-x Sensitive thin film-101, first electrode-122, second electrode-123, third electrode-132, fourth electrode-133, flexible metal lead-141, edge signal output pad-142. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 This invention provides a flexible infrared thermosensitive physiological signal detector and its fabrication method. The detector structure includes a detector body 1 and an encapsulation layer 2 covering the detector body 1. The detector body 1 receives temperature changes in a sensitive unit 12 caused by human thermal radiation and outputs a resistance signal or thermoelectric voltage signal corresponding to the temperature change. The detector body 1 includes a flexible substrate 11, a sensitive unit 12 disposed on the flexible substrate 11, and a reference unit 13. A thermal isolation region 121 is disposed below the sensitive unit 12, and an infrared shielding layer 131 is disposed above the reference unit 13. The encapsulation layer is one or more of Parylene, fluoropolymer, polyimide, epoxy resin, or siloxane, and the infrared shielding layer is a metal. The shielding layer, carbon-based shielding layer, or multi-layer composite shielding layer serves to weaken the ability of the reference unit 13 to receive human body thermal radiation, allowing the reference unit 13 to primarily reflect common-mode interference signals such as ambient background temperature, overall device temperature drift, and mechanical disturbances. By differentially processing the signals of the sensitive unit 12 and the reference unit 13, the stability and signal-to-noise ratio of the device output signal can be significantly improved. Signal output terminals 14 are electrically connected to the sensitive unit 12 and the reference unit 13, respectively. The encapsulation layer 2 forms an infrared sensing window 21 above the sensitive unit 12. An interval structure 211, 0.1-3 mm in diameter, is provided around the infrared sensing window 21 to maintain a predetermined gap with the human body surface. Both the sensitive unit 12 and the reference unit 13 include Te. x Se 1-x Sensitive film 101, the Te x Se 1-x The value of x in the sensitive film 101 ranges from 0.4 to 0.9, and the Te... x Se 1-x The thickness of the sensitive film 101 is 20-300 nm, and the Te x Se 1-x The sensitive thin film 101 has an amorphous or polycrystalline structure.

[0022] The flexible substrate 11 supports the entire device structure. Its material is preferably one or more flexible polymers such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polydimethylsiloxane (PDMS). These materials possess good mechanical flexibility, processability, and certain thermal stability, enabling them to adapt to the bending deformation of the human body surface, thereby ensuring stable operation of the device under attachment, bending, and dynamic wearing conditions. xSe 1-x The sensitive thin film 101 is the core functional layer, formed by thermal evaporation or co-evaporation processes. Its thickness is preferably 20-300 nm, more preferably 50-200 nm. Within this thickness range, good film uniformity and thermosensitive response characteristics are ensured, while also reducing heat capacity and improving sensitivity to slight temperature changes. x Se 1-x The value of x in the sensitive thin film 101 can be adjusted within a certain range to optimize the film's conductivity, thermodynamic response characteristics, and device stability.

[0023] Te on the sensitive unit 12 x Se 1-x The sensitive thin film 101 is electrically connected to a first electrode 122 and a second electrode 123. The first electrode 122 and the second electrode 123 are spaced apart and form a coplanar electrode structure on the same side. The Te on the reference unit 13 x Se 1-x The sensitive film 101 is electrically connected to a third electrode 132 and a fourth electrode 133. The third electrode 132 and the fourth electrode 133 are spaced apart and form a coplanar electrode structure on the same side. The first electrode 122, the second electrode 123, the third electrode 132 and the fourth electrode 133 are each independently selected from one or more of Au, Ag, Al, Cu, Ti, Cr, Ni, Pt and their composite metal films. The distance between the first electrode 122 and the second electrode 123 is 5μm-200μm and the electrode thickness is 20-200nm. The first electrode 122 and the second electrode 123 are made of different materials or have different thicknesses to form an asymmetric electrode structure to enhance the thermoelectric response or temperature difference response of the sensitive unit 12.

[0024] Wherein, the first electrode 122 and the second electrode 123 are disposed on the Te of the sensing unit 12 x Se 1-x The same side surface of the sensitive film 101 and respectively with the Te x Se 1-x Sensitive film 101 has overlapping contact at both ends, and the Te between the two is... x Se 1-x The sensitive thin film 101 region constitutes an effective thermistor region or thermoelectric response region; the third electrode 132 and the fourth electrode 133 are disposed on the reference electrode in the same manner. x Se 1-x The sensitive thin film 101 is attached to the same side surface and overlaps with both ends to form a reference unit 13. The first electrode 122, the second electrode 123, the third electrode 132, and the fourth electrode 133 are not upper and lower sandwich electrodes, but are connected to Te. x Se 1-xThe sensitive thin film 101 forms a coplanar electrical connection on the same side, which can reduce the obstruction of incident infrared thermal radiation and facilitate low-temperature patterning fabrication on a flexible substrate.

[0025] The thermal isolation area 121 is a groove-filled thermal isolation area located below the sensitive unit 12. The groove of the groove-filled thermal isolation area is filled with a low thermal conductivity polymer or a low thermal conductivity porous polymer and is cured and planarized to form a low thermal conductivity support surface that is flush with or substantially flush with the upper surface of the flexible substrate 11, so that the Te x Se 1-x A sensitive thin film 101 is deposited on the low thermal conductivity support surface, wherein the low thermal conductivity polymer or low thermal conductivity porous polymer is selected from one or more of PDMS, siloxane, porous polyimide, porous epoxy resin or aerogel composite polymer.

[0026] Among them, Te x Se 1-x The sensitive film 101 is not deposited at the bottom of the unfilled groove; therefore, the groove-filled thermal isolation area is located in Te. x Se 1-x Between the sensitive thin film 101 and the flexible substrate 11, vertical thermal conduction and lateral thermal diffusion can be reduced, while maintaining Te x Se 1-x The continuity and smoothness of the deposition surface of the sensitive thin film 101 are ensured to avoid Te from being affected by groove steps. x Se 1-x The sensitive film 101 is broken or the electrode contact is unstable.

[0027] The signal output terminal 14 includes flexible metal leads 141 electrically connected to the first electrode 122, the second electrode 123, the third electrode 132, and the fourth electrode 133, respectively, and an edge signal output pad 142 disposed in the edge region of the flexible substrate 11. The flexible metal leads 141 and the corresponding electrodes are patterned on the same flexible substrate 11 surface by the same layer of metal or stacked metal. The edge signal output pad 142 is connected to a differential amplifier circuit, a bridge circuit, a low-noise readout circuit, or a controller by anisotropic conductive adhesive, conductive silver paste, crimping, low-temperature soldering, or a flexible flat cable, so as to compensate for environmental temperature drift using the reference unit 13.

[0028] The flexible metal leads 141 of the signal output terminal 14 are led out from the first electrode 122, the second electrode 123, the third electrode 132, and the fourth electrode 133, respectively, and extend along the surface of the flexible substrate 11 to the edge region of the device. The edge signal output pad 142 can be configured with four ports: S+, S-, R+, and R-. S+ and S- correspond to the output terminals of the sensitive unit 12, and R+ and R- correspond to the output terminals of the reference unit 13. To improve bending reliability, the flexible metal leads 141 can adopt a serpentine, arc-shaped, or widened transition. The structure is protected by a Parylene, polyimide, or siloxane encapsulation layer, with external connection windows reserved only in the edge pad area. The detector body 1 only includes a low-temperature compatible structure such as a sensitive unit 12, a reference unit 13, a flexible metal lead 141, and an edge signal output pad 142. The differential amplifier, filter circuit, analog-to-digital converter, and controller can be arranged on an external flexible circuit or a rigid-flexible combined circuit module, thereby avoiding high-temperature soldering, rigid component mounting, or large-area rigid circuits directly acting on the functional area of ​​the flexible substrate 11.

[0029] Working principle: Utilizing a coplanar electrode structure on the same side, the electrodes and Te... x Se 1-x The sensitive thin film 101 is disposed on the same side surface, thereby avoiding the blocking of incident thermal radiation by the traditional sandwich electrode structure and facilitating flexible device fabrication and subsequent packaging. The coplanar electrode can be used to detect Te. x Se 1-x The resistance change caused by temperature variations in the sensitive thin film 101 can also be enhanced by asymmetric electrode design to increase the thermoelectric signal output. This allows the device to achieve electrical conversion of changes in human body thermal radiation using a thermistor, thermoelectric, or a combination of both. Since human respiration and surface temperature fluctuations typically manifest as slow and small-amplitude thermal radiation changes, this invention does not rely on a simple direct photogenerated carrier collection mechanism, but rather utilizes Te... x Se 1-x The thermoelectric response, thermal isolation enhancement design, and differential compensation mechanism of the sensitive film 101 enable the effective extraction of weak physiological thermal signals from the human body, making it suitable for continuous monitoring in room temperature, uncooled, and flexible wearable scenarios.

[0030] A method for fabricating the flexible infrared thermosensitive physiological signal detector includes the following steps: Step S1: Cleaning and surface pretreatment of the flexible substrate 11. The specific cleaning and surface pretreatment methods are as follows: the flexible substrate 11 is cleaned with acetone, isopropanol and deionized water in sequence, and then dried with nitrogen and subjected to plasma surface treatment. Step S2: On the flexible substrate 11, grooves are formed in the region corresponding to the sensitive unit 12 using laser etching, plasma etching, molding, or patterned sacrificial layer methods. Low thermal conductivity polymers or low thermal conductivity porous polymers are filled into the grooves, and a planarization process is performed using thermosetting, photosetting, or room temperature curing methods, followed by scraping, spin coating, backfilling, imprinting, or light etching to form a groove-filled thermal insulation area with a low thermal conductivity support surface. This allows for subsequent Te... x Se 1-x Sensitive thin 101 films can be deposited on a continuous, flat, low thermal conductivity support surface; Step S3: Using a pre-alloyed evaporation source or a dual-source co-evaporation thermal deposition process, Te is deposited on the low thermal conductivity support surface of the groove-filled thermal isolation zone and in the corresponding area of ​​the reference unit 13. x Se 1-x Sensitive thin film 101 forms the functional thin film in sensitive unit 12 and reference unit 13, wherein the evaporation vacuum degree is 1×10 -3 Pa-1×10 -5 Pa, substrate temperature 20-120℃, deposition rate 0.1-2.0 nm / s; After step S3 is completed, the method further includes processing the Te. x Se 1-x The sensitive film 101 undergoes post-annealing treatment at a temperature of 60-180°C for 1-30 minutes. Step S4, in the sensitive unit 12, Te x Se 1-x A first electrode 122 and a second electrode 123 are fabricated on the sensitive thin film 101, and the Te in the reference unit 13 x Se 1-x A third electrode 132 and a fourth electrode 133 are fabricated on the sensitive thin film 101, and flexible metal leads 141 and edge signal output pads 142 that are electrically connected to the first electrode 122, the second electrode 123, the third electrode 132, and the fourth electrode 133 are fabricated simultaneously or in steps to form coplanar electrodes on the same side and flexible signal output terminals 14. The fabrication process is carried out under low temperature conditions suitable for flexible substrates, and preferably a mask patterning or low temperature patterning process is used to avoid thermal deformation or performance degradation of the flexible substrate and the low thermal conductivity filling layer. The first electrode 122, the second electrode 123, the third electrode 132, the fourth electrode 133, the flexible metal lead 141, and the edge signal output pad 142 are prepared by one or more of the following methods: thermal evaporation, electron beam evaporation, magnetron sputtering, inkjet printing, screen printing, or transfer printing. The first electrode 122 and the second electrode 123 are respectively bonded to the Te of the sensing unit 12. x Se 1-xThe two ends of the sensitive thin film 101 overlap, so that the third electrode 132 and the fourth electrode 133 are respectively connected to the reference unit 13. x Se 1-x The sensitive film 101 overlaps at both ends to form a coplanar electrode structure on the same side; simultaneously or subsequently, a flexible metal lead 141 and an edge signal output pad 142 are formed to be continuously connected to the first to fourth electrodes. The edge signal output pad is used to connect to an external differential readout circuit and controller via anisotropic conductive adhesive, conductive silver paste, crimping or flexible flat cable. In the preferred fabrication method, the electrodes, flexible metal leads 141, and edge signal output pads 142 are formed in one step by deposition using the same Ti / Au, Cr / Au, Ti / Cu / Au, or Ag conductive layer via a mask. Alternatively, the electrode layer can be formed first, followed by the thickened trace layer and pad layer. To accommodate the bending of the flexible substrate, the thickness of the flexible metal leads 141 is preferably 50-500 nm, and the edge signal output pads 142 can be locally thickened to 0.1-5 μm. A flexible reinforcement layer is provided below or above the edge signal output pads 142 to improve mechanical reliability under external connection and repeated bending conditions. x Se 1-x During the deposition of the sensitive thin film 101, the microstructure and electrical properties of the film can be adjusted by controlling the substrate temperature and post-processing conditions, so that it can exhibit an amorphous or polycrystalline state, thereby optimizing the thermal response characteristics and operational stability of the device.

[0031] Step S5: An infrared shielding layer 131 is prepared above the reference unit 13 to reduce the direct response of the reference unit to human body thermal radiation. Step S6: An encapsulation layer 2 is formed on the surface of the detector body 1 by chemical vapor deposition, spin coating, spraying, scraping or lamination, and an infrared sensing window 21 is retained above the sensitive unit 12. Step S7: Set the gap structure 211 for controlling the gap with the human body surface to obtain a flexible infrared thermosensitive physiological signal detector.

[0032] Specifically, the spacer structure 211 is made of a flexible polymer sheet with a thickness of 0.1-3mm, preferably 0.3-0.8mm, which is die-cut or laser-cut to form an annular spacer corresponding to the infrared sensing window 21. The annular spacer is then attached to the periphery of the infrared sensing window 21 to control the predetermined air gap between the device and the human body surface.

[0033] Example 1, PI-based flexible differential Te 0.7 Se 0.3 Fabrication method of infrared thermal detector The preparation steps include the following: In substrate preparation step S1, a 25μm thick polyimide film is selected as a flexible substrate and ultrasonically cleaned in acetone, isopropanol and deionized water in sequence, cleaning for 10 minutes in each solution. After that, it is dried with nitrogen and subjected to oxygen plasma surface treatment for 30-120 seconds. In step S2, a localized groove is formed on the polyimide substrate in the area where the sensitive unit 12 is to be formed, using laser etching or plasma etching. The groove depth is 10-8 μm, and a polyimide support layer of approximately 7-15 μm thickness is retained at the bottom of the groove. Subsequently, low thermal conductivity porous PDMS, low thermal conductivity siloxane, or aerogel composite polymer is filled into the groove and cured at 60-100°C for 10-60 min. After curing, surface planarization is performed by backfilling with a scraping agent, imprinting, or light plasma etching, making the upper surface of the filling layer flush or substantially flush with the surrounding polyimide substrate surface, forming a groove-filled thermal isolation region with a low thermal conductivity support surface. This structure facilitates subsequent Te x Se 1-x The sensitive film 101 is deposited on a flat, low thermal conductivity support surface, rather than directly on the bottom of the unfilled groove, thereby avoiding shortening the heat conduction path and reducing heat diffusion from the sensitive area to the substrate; the reference unit 13 can remain unfilled or have the same filled structure. Te x Se 1-x In the sensitive thin film deposition step S3, the pre-prepared Te 0.7 Se 0.3 The alloy evaporation source was placed inside the evaporation boat of the thermal evaporation equipment, and a vacuum of 5 × 10⁻⁴ Pa was applied. The substrate temperature was controlled at 40 °C, and a 120 nm thick Te alloy was deposited at a deposition rate of 0.2–0.3 nm / s. 0.7 Se 0.3 Alloy thin film, Te of sensing unit 12 0.7 Se 0.3 Alloy films are deposited on the planarized surface of the groove-filled thermal insulation region and the overlapping areas on both sides, with reference unit 13's Te 0.7 Se 0.3 An alloy thin film is deposited in the region corresponding to reference cell 13 to form a sensitive cell thin film and a reference cell thin film, respectively. In step S4, the electrode and signal output terminal fabrication process involves depositing Ti / Au composite electrodes at both ends of the sensitive unit film using a mask evaporation method to form a first electrode 122 and a second electrode 123. The electrode thickness is 10-60 nm, and the electrode spacing is 30-50 μm. A third electrode 132 and a fourth electrode 133 with identical structures are fabricated on the reference unit film. Simultaneously, flexible metal leads 141 are formed, connecting the first to fourth electrodes respectively, using the same mask or a second mask. These flexible metal leads 141 are extended to the edge of the polyimide substrate to form S+, S-, R+, and R- edge signal output pads 142. The edge signal output pads 142 can be locally thickened using Ti / Au, Cr / Au, or Ti / Cu / Au multilayer metals and can be cryogenically bonded to anisotropic conductive adhesive, flexible flat cables, or flexible printed circuit boards. In the reference cell shielding step S5, an infrared shielding layer 131 of Al material with a thickness of 150-300nm is deposited on the reference cell 13 to suppress the direct effect of external infrared radiation on the reference cell. In the encapsulation and window formation step S6, a Parylene encapsulation layer 2 with a thickness of 0.5-2μm is deposited on the surface of the detector body 1, and an infrared sensing window 21 of 2mm×2mm is retained above the sensing unit 12. In step S7, a spacer structure 211 with a thickness of 0.3-0.8 mm is formed around the infrared sensing window 21 to maintain a stable air gap between the device and the human body surface during use. In step S8 of the readout connection and control circuit, the S+, S-, R+, and R- edge signal output pads 142 are connected to the external readout module via anisotropic conductive adhesive, conductive silver paste, low-temperature bonding, or flexible flat cables. The external readout module includes a differential bridge or differential instrumentation amplifier, a low-noise filter circuit, an analog-to-digital converter, and a controller. The detector body 1 mainly retains the sensitive unit 12, the reference unit 13, the flexible metal lead 141, and the edge signal output pads 142. The controller and thicker electronic components can be set on the external flexible circuit or a rigid-flexible combined small module to improve the process compatibility of the flexible substrate and the wearing reliability.

[0034] In resistive readout mode, the sensing element 12 is equivalent to a resistor Rsens, and the reference element 13 is equivalent to a resistor Rref. The two are connected to adjacent or symmetrical arms of the differential bridge, and together with two precision matching resistors R0, they form a bridge. Human body thermal radiation mainly acts on the sensing element 12, causing Rsens to change with temperature. The reference element 13, due to the infrared shielding layer 131, mainly responds to environmental temperature drift and device common-mode disturbances. The two midpoints of the bridge output V+ and V-, which are differentially amplified by the instrumentation amplifier and then enter the filter circuit, analog-to-digital converter, and controller.

[0035] In thermoelectric voltage readout mode, the thermoelectric voltage Vsens of the sensing unit 12 is output between the first electrode 122 and the second electrode 123, and the thermoelectric voltage Vref of the reference unit 13 is output between the third electrode 132 and the fourth electrode 133. Vsens and Vref are input to a high input impedance differential amplifier, and after low noise filtering and analog-to-digital conversion, they are sent to the controller. The controller performs baseline drift subtraction, bandpass filtering, peak detection or spectrum analysis to obtain respiratory-related thermal pulse signals and slow changes in body surface temperature signals.

[0036] The controller can be a low-power microcontroller, an analog front-end chip, a system-on-a-chip, or an external processing module on a flexible circuit board. It is electrically connected to the flexible detector through edge signal output pads 142 and flexible connectors. This structure avoids directly fabricating rigid chips on flexible thermal sensitive areas, and can take into account the flexible substrate fabrication process, packaging reliability, and subsequent wearable integration.

[0037] Among them, flexible connectors are existing technologies and are electrical connection components for flexible cables, flexible conductive sheets, etc.

[0038] Example 2: Application for respiratory signal detection The PI-based flexible differential Te obtained in Example 1 0.7 Se 0.3 An infrared thermal detector is fixed to a flexible support on the inside of the mask or near the nose, with the infrared sensing window 21 facing the nostrils and maintaining a detection distance of 2-10mm between the infrared sensing window 21 and the nostril outlet. During the user's exhalation and inhalation, the thermal radiation intensity near the nose undergoes periodic changes, and these changes, acting on the sensitive unit 12, cause a Te... 0.7 Se 0.3 Temperature changes in the alloy thin film cause the device to output corresponding resistance or voltage signals.

[0039] Among them, the existing technology of flexible support components specifically refers to the U-shaped breathable inner support bracket or medical-grade aluminum foil or galvanized iron wire inside the mask. The U-shaped breathable inner support bracket is made of one of the following materials: food-grade ABS, TPE, and silicone. It can also be a flexible pad made of skin-friendly materials such as medical-grade TPU and soft silicone, which directly conforms to the contour of the nose.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0041] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A flexible infrared thermosensitive physiological signal detector, characterized in that: Its structure includes a detector body (1) and an encapsulation layer (2) covering the detector body (1). The detector body (1) is used to receive the temperature change of the sensitive unit (12) caused by human body thermal radiation and output a resistance signal or thermoelectric voltage signal corresponding to the temperature change. The detector body (1) includes a flexible substrate (11), a sensitive unit (12) disposed on the flexible substrate (11), and a reference unit (13). A thermal isolation area (121) is disposed below the sensitive unit (12), and an infrared shielding layer (131) is disposed above the reference unit (13) to reduce the response of the reference unit (13) to external infrared radiation. Signal output terminals (14) are electrically connected to the sensitive unit (12) and the reference unit (13), respectively. An infrared sensing window (21) is formed above the sensitive unit (12). The sensitive unit (12) and the reference unit (13) both include Te. x Se 1-x Sensitive film (101), Te on the sensitive unit (12) x Se 1-x The sensitive thin film (101) is electrically connected to a first electrode (122) and a second electrode (123). The first electrode (122) and the second electrode (123) are spaced apart and form a coplanar electrode structure on the same side. The Te on the reference unit (13) x Se 1-x The sensitive film (101) is electrically connected to a third electrode (132) and a fourth electrode (133), wherein the third electrode (132) and the fourth electrode (133) are spaced apart and form a coplanar electrode structure on the same side.

2. The flexible infrared thermosensitive physiological signal detector according to claim 1, characterized in that: The thermal isolation area (121) is a groove-filled thermal isolation area located below the sensitive unit (12). The groove of the groove-filled thermal isolation area is filled with a low thermal conductivity polymer or a low thermal conductivity porous polymer and is cured and planarized to form a low thermal conductivity support surface that is flush with or substantially flush with the upper surface of the flexible substrate (11), so that the Te x Se 1-x A sensitive thin film (101) is deposited on the low thermal conductivity support surface.

3. The flexible infrared thermosensitive physiological signal detector according to claim 2, characterized in that: The Te x Se 1-x The value of x in the sensitive film (101) ranges from 0.4 to 0.

9.

4. The flexible infrared thermosensitive physiological signal detector according to claim 3, characterized in that: The Te x Se 1-x The thickness of the sensitive thin film (101) is 20-300 nm, and the Te x Se 1-x The sensitive thin film (101) has an amorphous or polycrystalline structure.

5. A flexible infrared thermosensitive physiological signal detector according to claim 1, characterized in that: The infrared sensing window (21) is surrounded by a gap structure (211) for maintaining a predetermined gap with the human body surface, the predetermined gap being 0.1-3mm.

6. A flexible infrared thermosensitive physiological signal detector according to claim 1, characterized in that: The signal output terminal (14) includes a flexible metal lead (141) electrically connected to the first electrode (122), the second electrode (123), the third electrode (132) and the fourth electrode (133) respectively, and an edge signal output pad (142) disposed in the edge region of the flexible substrate (11).

7. A method for preparing a flexible infrared thermosensitive physiological signal detector according to any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Clean and pre-treat the surface of the flexible substrate (11); Step S2: A groove is formed in the region corresponding to the sensitive unit (12) of the flexible substrate (11), and a low thermal conductivity polymer or a low thermal conductivity porous polymer is filled in the groove. After curing and planarization, a groove-filled thermal isolation area with a low thermal conductivity support surface is formed. Step S3: Te is deposited on the low thermal conductivity support surface of the groove-filled thermal isolation zone and the corresponding area of ​​the reference unit (13) using a thermal evaporation process. x Se 1-x A sensitive thin film (101) is formed to create a functional thin film in the sensitive unit (12) and the reference unit (13); Step S4, in the sensitive unit (12) Te x Se 1-x A first electrode (122) and a second electrode (123) are fabricated on the sensitive thin film (101), and the Te in the reference unit (13) x Se 1-x A third electrode (132) and a fourth electrode (133) are fabricated on a sensitive thin film (101), and flexible metal leads (141) and edge signal output pads (142) electrically connected to the first electrode (122), the second electrode (123), the third electrode (132), and the fourth electrode (133) are fabricated simultaneously or in steps to form coplanar electrodes on the same side and flexible signal output terminals (14). Step S5: An infrared shielding layer (131) is prepared above the reference unit (13). Step S6: Form an encapsulation layer (2) on the surface of the detector body (1) and retain an infrared sensing window (21) above the sensitive unit (12). Step S7: Set the gap structure (211) for controlling the gap with the human body surface to obtain a flexible infrared thermosensitive physiological signal detector.

8. The method for fabricating a flexible infrared thermosensitive physiological signal detector according to claim 7, characterized in that: After step S3 is completed, the method further includes processing the Te. x Se 1-x The sensitive film (101) is subjected to post-annealing treatment at a temperature of 60-180°C for a time of 1-30 min.

9. The method for preparing the flexible infrared thermosensitive physiological signal detector according to claim 7, characterized in that: In step S4, the first electrode (122), the second electrode (123), the third electrode (132), the fourth electrode (133), the flexible metal lead (141), and the edge signal output pad (142) are prepared by one or more of the following methods: thermal evaporation, electron beam evaporation, magnetron sputtering, inkjet printing, screen printing, or transfer printing.

10. The method for fabricating a flexible infrared thermosensitive physiological signal detector according to claim 7, characterized in that: In step S6, the encapsulation layer (2) is formed by chemical vapor deposition, spin coating, spraying, scraping or lamination.

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