A multi-layer integrated flexible multimodal sensor

Abstract

The present invention relates to a multi-layer integrated flexible multimodal sensor, belonging to the technical field of physiological signal detection; the problem that the multimodal sensors in the prior art mostly adopt a planar distribution mode, have a large area and a low degree of integration is solved; the sensor of the present invention comprises a pressure sensing layer, a non-exposed sensing layer, an exposed sensing layer and a flexible packaging layer from bottom to top; the pressure sensing layer comprises a first flexible substrate and a pressure sensor and a corresponding lead wire arranged on the first flexible substrate; the non-exposed sensing layer comprises a second flexible substrate arranged on the pressure sensing layer and a non-exposed sensor and a corresponding lead wire arranged on the second flexible substrate; the exposed sensing layer comprises a third flexible substrate arranged on the non-exposed sensing layer and an exposed sensor and a corresponding lead wire arranged on the third flexible substrate; the flexible packaging layer covers the exposed sensing layer, and etches out the area directly above the exposed sensor, the neural electrode and the electrical stimulator.

Description

Technical Field

[0001] The present invention relates to the technical field of physiological signal detection, and in particular to a multi-layer integrated flexible multi-modal sensor. Background Art

[0002] With the continuous development of related technologies in the field of medical health, the application of implantable health monitoring equipment is becoming more and more extensive. Flexible electronics, due to their light, thin, soft and small characteristics, are very suitable for many scenarios in the field of medical health that have high requirements for the size, weight and integration of equipment, such as elderly care, daily health management, sports training, etc. Specifically, chips and integrated circuits are made flexible, and miniature flexible devices are implanted into the human body to detect human physiological information without affecting human health and living habits, thereby assisting medical institutions, individual users, and athletes in disease treatment, health management and training guidance. In order to meet the needs of flexible sensors implanted in the human body, the miniaturization and integration of sensors are new development trends in the future. However, current flexible sensors generally face problems such as large area and volume and low degree of integration, which restrict the development of flexible electronic technology.

[0003] Existing flexible sensor integration technologies can be mainly divided into two forms: various sensors distributed on a single substrate and heterogeneous integration on different substrates. However, both methods face the problem of large area and unsuitable for implantable application scenarios, or some smaller sensors cannot meet multimodal testing requirements due to the single type of sensor. Therefore, studying the high-density integration technology of multimodal sensors and exploring feasible design solutions that can achieve miniaturization and miniaturization of sensors are of vital importance to meet the needs of multi-signal detection of implantable sensors, reduce implantation trauma and obtain more accurate signals. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a multi-layer integrated flexible multimodal sensor to solve the problem that the multimodal sensors in the prior art mostly adopt a planar distribution method, have a large area and low integration.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a multi-layer integrated flexible multi-modal sensor, which comprises, from bottom to top, a pressure sensing layer, a non-exposed sensing layer, an exposed sensing layer and a flexible packaging layer;

[0007] The pressure sensing layer includes a first flexible substrate, a pressure sensor disposed on the first flexible substrate, and a lead wire corresponding to the pressure sensor;

[0008] The non-exposed sensing layer includes a second flexible substrate disposed on the pressure sensing layer, and a non-exposed sensor disposed on the second flexible substrate and a lead wire corresponding to the non-exposed sensor;

[0009] The exposed sensing layer includes a third flexible substrate disposed on the non-exposed sensing layer, and an exposed sensor disposed on the third flexible substrate and a lead wire corresponding to the exposed sensor;

[0010] The flexible packaging layer covers the exposed sensing layer, and etches away the area directly above the exposed sensors, neural electrodes and electrical stimulators.

[0011] Furthermore, the pressure sensing layer, the non-exposed sensing layer and the exposed sensing layer of the multimodal sensor are arranged in a stepped shape at the interface of the multimodal sensor; and gold fingers of the lead wires corresponding to each layer are arranged at each step.

[0012] Furthermore, the lead wire is arranged as a curved pattern of any shape;

[0013] The lead wires of each layer extend from the layer where the lead wire is located to the interface of the multimodal sensor, and an exposure process is performed at the stepped position of the interface.

[0014] Furthermore, the exposed sensor includes a potassium and sodium ion sensor, an oxygen partial pressure sensor, a neural electrode and an electrical stimulator; the potassium and sodium ion sensor and the oxygen partial pressure sensor adopt an embedded probe structure or a sensitive layer protruding probe structure;

[0015] When the potassium and sodium ion sensors and the oxygen partial pressure sensor adopt an embedded probe structure, the third flexible substrate and the second flexible substrate have the same size of 4mm*8mm; the potassium and sodium ion sensors, the oxygen partial pressure sensor, the neural electrodes and the electrical stimulator are all arranged on the third flexible layer and are located within the range of the 4mm*8mm flexible substrate.

[0016] Furthermore, when the potassium-sodium ion sensor and the oxygen partial pressure sensor adopt a sensitive layer protruding probe structure, the third flexible substrate, in addition to the 4mm*8mm shape, also includes a plurality of protruding probes made of the same material as the third flexible substrate, and the potassium-sodium ion sensor and the oxygen partial pressure sensor are arranged on the protruding probes; the plurality of protruding probes are arranged to avoid the multimodal sensor interface.

[0017] Furthermore, the first flexible substrate, the second flexible substrate and the third flexible substrate are made of the same or different substrate materials.

[0018] Furthermore, the flexible substrate material is photolithographic PI or SU-8; or non-photolithographic PI or Parylene.

[0019] Furthermore, the preparation process of the second flexible substrate and the third flexible substrate includes:

[0020] Spin coating a flexible substrate material twice on the pressure sensing layer and the non-exposed sensing layer;

[0021] Etching the flexible substrate material using an oxygen dry method to obtain the second flexible substrate and the third flexible substrate material which are flat;

[0022] According to the component ratio of oxygen to carbon tetrafluoride of 1:1 by volume, the flat surfaces of the second flexible substrate and the third flexible substrate are etched by a plasma etching method to obtain the second flexible substrate and the third flexible substrate; the thickness of the flexible substrate is 7-10 μm.

[0023] Furthermore, the bottom surface size of the multimodal sensor is 4mm*8mm, and the thickness is less than 300μm;

[0024] The preparation process of the pressure sensor includes:

[0025] A first flexible substrate is provided which is bilaterally symmetrical and has a shape of 8mm*8mm;

[0026] Patterning 2n left-right symmetrical pressure sensitive film windows on the first flexible substrate, where n is the number of pressure sensors;

[0027] Preparing an upper electrode plate and a lower electrode plate of a pressure sensor corresponding to the 2n pressure-sensitive film windows, and preparing a lead wire of the pressure sensor on the first flexible substrate;

[0028] The first flexible substrate is folded in half along the symmetry axis so that the lower electrode plate is aligned and covered with the upper electrode plate, and a pressure sensor film is added in the middle to form a pressure sensor.

[0029] Furthermore, preparing lead wires on the second flexible substrate and the third flexible substrate includes:

[0030] Depositing a layer of metal chromium on the second flexible substrate and the third flexible substrate, wherein the thickness of the metal chromium is less than 15 nm;

[0031] The lead wire of solid metal material is prepared by photolithography patterning process on metal chromium;

[0032] Or a lead wire made of conductive liquid material is prepared on metallic chromium by screen printing or inkjet printing; the thickness of the lead wire is less than 300 nm.

[0033] Beneficial effects of this technical solution:

[0034] 1. The multi-layer integrated flexible multimodal sensor of the present invention adopts a three-layer sensor structure, wherein the first and third layers are open exposed sensors, which can be used for sensing quantities that communicate information with the outside world, such as chemical quantities (potassium and sodium ions, oxygen) and physical quantities (electrophysiological electrodes, pressure sensors); the second layer is a non-exposed sensor, which can be used for monitoring physical quantities that do not necessarily contact the outside world, such as temperature sensors, stress sensors, etc. The different flexible substrates of the sensor of the present invention can adopt the same or different flexible substrate materials, and adopt non-heterogeneous integration means to form a multi-layer three-dimensional flexible sensor under the traditional MEMS process, thereby reducing the volume of the sensor.

[0035] 2. The lead wires of the present invention also adopt a layered structure, and there is no spatial and temporal intersection between the layers. The multiple layers of unconnected lead wires extend to the flexible FPC connector. Through the flexible substrate opening process, the lead wire interface is fully exposed, and each sensor part can be effectively connected to the signal processing unit through the FPC connector. The advantage of this connection method over the traditional single-layer parallel wiring is that there is no need to perform through-hole connection of multi-layer wiring, thereby reducing the difficulty of production and improving the yield rate.

[0036] 3. The multi-layer integrated sensor of the present invention can reduce its area from 2cm*3cm of the planar structure to 4mm*8mm when integrating the same number of sensors, while its height is similar to that of the planar structure, both less than 300μm, which greatly reduces the volume of the sensor and improves the integration.

[0037] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0039] Figure 1 Schematic diagram of the structure of a multi-modal implantable sensor according to an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the connection between an implantable sensor and an external processor according to an embodiment of the present invention;

[0041] Figure 3 The pressure sensor manufacturing process of the embodiment of the present invention;

[0042] Figure 4Schematic diagram of the design of an exposed sensor embedded in a probe according to an embodiment of the present invention

[0043] Figure 5 This is a schematic diagram of an exposed sensitive layer protruding probe design according to an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the exposure process of the lead wire at the step structure interface according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0046] A multi-layer integrated flexible multi-modal sensor in this embodiment, such as Figure 1 As shown, from bottom to top, it includes a pressure sensing layer, a non-exposed sensing layer, an exposed sensing layer and a flexible packaging layer; wherein the pressure sensing layer includes a first flexible substrate, and a pressure sensor and a lead wire corresponding to the pressure sensor arranged on the first flexible substrate; the non-exposed sensing layer includes a second flexible substrate arranged on the pressure sensing layer, and a non-exposed sensor and a lead wire corresponding to the non-exposed sensor arranged on the second flexible substrate; the exposed sensing layer includes a third flexible substrate arranged on the non-exposed sensing layer, and an exposed sensor and a lead wire corresponding to the exposed sensor arranged on the third flexible substrate; the flexible packaging layer covers the exposed sensing layer, and is obtained by etching away the area directly above the exposed sensor, the neural electrode and the electrical stimulator. Each layer of the flexible substrate of the multi-layer integrated flexible multi-modal sensor of this embodiment can select different flexible substrate materials according to the corresponding sensor type, and the thickness of each layer of the flexible substrate is 7-10μm; the thickness of the entire multi-modal sensor mostly comes from the pressure sensitive element of the pressure sensor, and the multi-layer structure has little effect on the thickness, and its thickness is similar to that of the planar multi-modal sensor, both less than 300μm; the sensor area of ​​this embodiment is 4mm*8mm, and can integrate at least 2 flexible pressure sensors, 2 shear force sensors, 2 oxygen partial pressure sensors, 2 groups of different potassium and sodium ion sensors, and 15 neural electrodes (neural electrodes can be used for neural signal acquisition or neural electrical stimulation, or through time division multiplexing, the same electrode has both electrical signal acquisition and neural electrical stimulation functions). In the case of integrating the same multi-category sensors, the multi-layer integrated structure of this embodiment greatly reduces the volume of the sensor. In practical applications, the multi-modal sensor of this embodiment is connected to an external processor (integrated circuit and wireless transmission circuit) through a flexible cable (FPC), such as Figure 2As shown in the figure, the implantable sensor which integrates multiple layers of flexible substrate and multiple flexible sensing units can be placed under human skin, in the cavity of human internal organs or in the cerebrospinal fluid above the cerebral cortex, and connected to the signal processing front-end circuit through flexible FPC cable, nylon thread or other biocompatible flexible wire as an insulating layer, and can monitor muscle temperature, muscle strength, myoelectricity, oxygen partial pressure, electrolyte concentration and other multi-parameter information.

[0047] Furthermore, the flexible multimodal sensor of this embodiment is an implantable sensor for physiological signal detection. Its flexible substrate material needs to select organic materials with high biocompatibility and be convenient for MEMS production (photolithography, etching, etc.). Therefore, the materials that can be used mainly include PI, parylene, SU-8, etc. By selecting the ratio of different components, the elastic modulus of the material is matched with the human brain tissue and skin tissue, so that it has commonalities with the cerebral cortex and skin, and the degree of damage to the brain tissue and skin caused by the implantable device is reduced as much as possible. Its specific size can be designed as a flexible multimodal sensor of different sizes and shapes according to the actual situation of the patient's wound and disease type.

[0048] For the materials of flexible substrates, one is the material that has photolithographic properties, such as photolithographic PI (negative photoresist properties) and SU-8, and the other is the material that does not have photolithographic properties, such as non-photolithographic PI and Parylene. For photolithographic flexible substrate materials, they can be patterned by photolithography technology when the material is formed, so that the structure formed is more precise. For non-photolithographic substrate materials, it is necessary to etch after each layer of substrate material is spin-coated, and before etching, it is necessary to use photoresist for patterning and protection; if the requirements for the lines are not high, hard mask protection can be used and then etching can be performed using oxygen, carbon tetrafluoride, argon or other gases.

[0049] In practical applications, the mechanical parameters of the substrate material, such as stiffness, Young's modulus, yield coefficient, etc., can be determined according to different application scenarios, and then the appropriate substrate and lead wire material and preparation process can be selected. When preparing the first layer of flexible substrate, a rigid substrate is required as a support plate for processing. Preferably, the support plate can be formed by depositing aluminum from silicon. After the multi-layer multimodal sensor is manufactured, the aluminum is removed by electrochemical anodic corrosion, so that the flexible sensor is peeled off from the support plate. The first flexible substrate in this embodiment includes two left-right symmetrical parts; the left-right symmetrical parts are used to prepare the upper and lower electrode plates of the pressure sensor, respectively.

[0050] For the pressure sensing layer, such as Figure 3 As shown, the preparation process of the pressure sensor includes:

[0051] A first flexible substrate is provided which is bilaterally symmetrical and has a size of 8 mm*8 mm;

[0052] Patterning 2n left-right symmetrical pressure sensitive film windows on the first flexible substrate, where n is the number of integrated pressure sensors;

[0053] An upper electrode plate and a lower electrode plate of a pressure sensor are prepared correspondingly on the 2n pressure-sensitive film windows, and a lead wire of the pressure sensor is prepared on the first flexible substrate;

[0054] The first flexible substrate is folded in half along the symmetry axis so that the lower electrode plate is aligned and covered with the upper electrode plate, and a pressure sensor film is added in the middle to form a pressure sensor.

[0055] In practical applications, after preparing a first flexible substrate of 8mm*8mm, firstly, a pressure-sensitive film window is patterned on the first flexible substrate, and then a layer of gold is deposited as an electrode and a lead wire of the pressure sensor. The method of this embodiment can produce a pressure sensor based on piezoresistor and a pressure sensor based on capacitance, both of which have an upper and lower electrode plate and an intermediate pressure-sensitive layer. The upper and lower electrodes are completed synchronously in this step. After removing the support plate, the lower electrode plate side is bent downward to align and cover with the other electrode, and a pressure sensor film is added in the middle to form a pressure sensor layer with a size of 4mm*8mm. The pressure sensor film in the two electrode plates is also prepared from flexible materials. After each layer of the sensing layer is prepared, it is also necessary to perform a patterned exposure process at the end of the lead wire. The lead wire after the exposure process can be electrically connected to the FPC cable to transmit the pressure signal detected by the pressure sensor to the external processing circuit.

[0056] In particular, the first flexible substrate, the second flexible substrate and the third flexible substrate of the present invention can use the same or different substrate materials. The flexible multilayer structure of the multimodal sensor of this embodiment will affect each other during the preparation process; for example, the surface of the pressure sensing layer and the non-exposed sensing layer of the sensor that have been prepared will form a concave-convex structure, and the preparation of sensors and lead wires on the concave-convex plane is likely to cause circuit breakage and poor contact between the metal lead wire and the flexible substrate. In order to solve this problem, when preparing the second flexible substrate and the third flexible substrate, this embodiment first spin-coats the flexible substrate material, such as PI, on the pressure sensing layer and the non-exposed sensing layer twice, and uses oxygen etching to obtain a flat upper surface of the sensing layer; on the other hand, plasma etching technology is used to treat the PI surface at a power of 50W in a manner of a volume ratio of oxygen to carbon tetrafluoride of 1:1. Through chemical reactions, a variety of functional groups (hydroxyl groups) are formed on the PI surface, and through physical bombardment, tiny depressions are generated on the surface, increasing the surface area, so that the binding between the flexible substrate and the metal is enhanced. In addition, taking advantage of the good bonding properties of metal chromium with the PI substrate and other metals, a layer of metal chromium is first deposited on the PI substrate and then other metal lead wires (such as gold, silver, platinum, etc.) are deposited to achieve a firm bond between the metal lead wire and the PI flexible substrate; wherein the thickness of the metal chromium is less than 15nm, and the thickness of the metal lead wire is less than 300nm.

[0057] The non-exposed flexible sensor in this embodiment includes a temperature sensor and a stress sensor;

[0058] A non-exposed flexible sensor is prepared on a second flexible substrate, comprising:

[0059] Deposit temperature sensor material and stress sensor material on the second flexible substrate and pattern them; or prepare temperature sensors and stress sensors on other substrates and transfer them to the second flexible substrate by pattern transfer to complete the preparation of temperature sensors and stress sensors.

[0060] For the exposed sensing layer, firstly, the third flexible substrate and the lead wires corresponding to the exposed sensor are prepared on the non-exposed sensing layer by the aforementioned method. The exposed sensor in this embodiment includes potassium and sodium ion sensors, oxygen partial pressure sensors, neural electrodes and electrical stimulators; the potassium and sodium ion sensors and oxygen partial pressure sensors adopt an embedded probe structure or a sensitive layer protruding probe structure;

[0061] Specifically, when the potassium and sodium ion sensors and the oxygen partial pressure sensors adopt an embedded probe structure, the third flexible substrate has the same 4mm*8mm shape as the second flexible substrate; the potassium and sodium ion sensors, oxygen partial pressure sensors, neural electrodes and electrical stimulators are all arranged on the third flexible layer and are located within the range of the 4mm*8mm flexible substrate.

[0062] When the potassium and sodium ion sensors and the oxygen partial pressure sensor adopt a sensitive layer protruding probe structure, the third flexible substrate, in addition to the 4mm*8mm shape, also includes a plurality of protruding probes made of the same substrate material, and the potassium and sodium ion sensors and the oxygen partial pressure sensor are arranged on the protruding probes; the plurality of protruding probes are arranged away from the multimodal sensor interface;

[0063] Preferably, the potassium and sodium ion sensor adopts an embedded probe design, and its preparation process includes:

[0064] A third flexible substrate having the same shape of 4 mm*8 mm as the second flexible substrate is prepared on the second flexible substrate; three electrodes are prepared on the third flexible substrate, including a potassium ion working electrode, a reference electrode and a sodium ion working electrode;

[0065] Depositing a conductive nanomaterial on the potassium ion working electrode and the sodium ion working electrode, and covering the conductive nanomaterial with a potassium ion selective film and a sodium ion selective film and curing the film;

[0066] The PVB material is deposited on the reference electrode and solidified to complete the preparation of the potassium and sodium ion sensor.

[0067] The preparation process of the oxygen partial pressure sensor for the embedded probe design includes:

[0068] On the third flexible substrate, three electrodes are manufactured by using a deposited metal film lift-off process, including a working electrode, a counter electrode and a reference electrode;

[0069] Depositing a proton conductive solid material on top of the electrode to complete the preparation of the oxygen partial pressure sensor;

[0070] The preparation process of neural electrodes and electrical stimulators includes:

[0071] On top of the third flexible substrate, a metal Pt or Ir electrode is made by a deposition or metal film stripping process, and porous nano-conductive particles are deposited to complete the preparation of the neural electrode and the electrical stimulator.

[0072] As a specific example, Figure 4As shown in the figure, when the embedded probe design is adopted, the multiple types of sensors on the exposed sensing layer are all located above the main body of the structure. First, the electrode materials of the potassium and sodium ion sensors are deposited on the prepared third flexible layer and patterned, wherein the working electrode can be Pt and the reference electrode can be Ag / AgCl; the oxygen partial pressure sensor material (such as Pt) is deposited and patterned; while depositing Pt, partial patterning can be performed to form multi-channel neural electrodes and electrical stimulation materials; further, conductive nanomaterials such as PEDOT:PSS are deposited above the working electrode of the potassium and sodium ion sensor, and then the potassium ion selective film and the sodium ion selective film are covered, and a mixed adhesive such as PVC and DOS synthesizer are cured to form a solid potassium ion and sodium ion selective film. PVB material is deposited and cured above the reference electrode of the ion sensor to reduce baseline drift. For the oxygen partial pressure sensor, a proton conductive solid material such as Nafion can be deposited above the electrode to form a sensitive membrane of the oxygen partial pressure sensor. For the neural electrode and the electrical stimulator, a layer of porous nano-conductive particles such as nano-gold wire, platinum black, etc. can be deposited to reduce their output impedance.

[0073] Furthermore, the potassium-sodium ion sensor and the oxygen partial pressure sensor adopt a sensitive layer protruding probe design, and the preparation process includes: avoiding the interface side of the multimodal sensor and the bending side of the sensor, extending the third flexible substrate by 2 mm and patterning multiple potassium-sodium ion sensor and oxygen partial pressure sensor protruding probes on the extended part; using deposition or metal film stripping process to manufacture the metal three electrodes and oxygen partial pressure sensor materials of the potassium-sodium ion sensor on the protruding probes; and depositing the corresponding electrochemical sensitive layer and solidified layer to fully wrap the metal three electrodes and oxygen partial pressure sensor materials of the potassium-sodium ion sensor by dripping.

[0074] It should be noted that the exposed sensing layer adopts a sensitive layer protruding probe structure, in which the potassium and sodium ion sensors and the oxygen partial pressure sensor extend outside the main structure of the multimodal sensor, such as Figure 5 As shown, the neural electrode is still located above the main body of the structure. The sensitive layer protruding probe design can be used to fully wrap the deposited electrochemical sensitive layer and its curing layer, such as PVC and DOS synthetic agent, by dripping, which can increase the adsorption area of ​​the sensitive layer, improve the adsorption stability and increase the sensitivity of the sensor.

[0075] Preferably, after the exposed sensing layer is prepared, a flexible packaging layer can be covered on the exposed sensing layer, and the thickness of the flexible packaging layer is 5 μm; the flexible insulating layer area directly above the potassium and sodium ion sensors, oxygen partial pressure sensors, neural electrodes and electrical stimulators is etched away by photolithography or shadow mask to achieve exposure processing of the exposed sensor.

[0076] Preferably, in order to improve the yield rate and signal quality of the sensor, the multi-layer sensing layer of the present invention adopts a stepped structure design at the interface of the multi-modal sensor, which is used to expose the lead wires of each layer at the stepped position at the interface of the layer, such as Figure 6 As shown, the advantage of the stepped structure design at the interface is that the lead wires of each layer do not need to be designed with a perforated structure. They only need to be extended from the current layer to the interface, and the thick gold fingers are reinforced at the interface position for exposure.

[0077] In this embodiment, lead wires need to be made in each sensing layer to connect the sensors of each layer and the connectors at the interface of the multimodal sensor; the shape of the lead wires can be designed as snake-shaped, arc-shaped, and any curved shapes, the purpose of which is to maintain the electrical stability of the lead wires during the stretching or compression of the substrate. If the lead wire density is high, a simple straight line shape can also be selected. In addition, based on the ladder structure design, there is no intersection in time and space between the lead wires between layers, and the multi-layer unconnected lead wires extend to the joint part of the multimodal sensor. Through the flexible substrate opening process, the full exposure of the lead wire interface is achieved, and then the various sensor parts can be effectively connected to the signal processing unit through the FPC connector. The advantage of the lead wire design method of this embodiment over the traditional single-layer parallel routing of the lead wire is that there is no need for through-hole connection of the multi-layer routing, thereby reducing the difficulty of production and greatly improving the yield rate and signal quality.

[0078] In summary, the multi-layer integrated flexible multimodal sensor provided by the embodiment of the present invention integrates a variety of physiological and biochemical sensors inside a multi-layer substrate material, and adopts a three-layer sensor structure, wherein the first and third layers are open exposure sensors, which can be used for sensing quantities that communicate information with the outside world, such as chemical quantities (potassium and sodium ions, oxygen) and physical quantities (electrophysiological electrodes, pressure sensors); the second layer is a non-open exposure sensor, which can be used for monitoring physical quantities that are not necessarily in contact with the outside world, such as temperature sensors, stress sensors, etc. Each layer can adopt a different flexible substrate material, and adopts a non-heterogeneous integration method to form a multi-layer three-dimensional flexible sensor under the traditional MEMS process. And the lead wire design of the present invention also adopts a layered structure, and there is no intersection in time and space between the layers. The multi-layer unconnected lead wires extend to the joint part of the multimodal sensor. Through the flexible substrate opening process, the full exposure of the lead wire interface is achieved, and then each sensor part can be effectively connected to the signal processing unit through the FPC connector. The advantage of this connection method over traditional single-layer parallel routing is that it does not require through-hole connections for multi-layer routing, thereby reducing the difficulty of production and improving the yield and signal quality.

[0079] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0080] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A multi-layer integrated flexible multimodal sensor, characterized in that: The sensor comprises, from bottom to top, a pressure sensing layer, a non-exposed sensing layer, an exposed sensing layer and a flexible packaging layer; The pressure sensing layer includes a first flexible substrate, a pressure sensor disposed on the first flexible substrate, and a lead wire corresponding to the pressure sensor; The non-exposed sensing layer includes a second flexible substrate disposed on the pressure sensing layer, and a non-exposed sensor disposed on the second flexible substrate and a lead wire corresponding to the non-exposed sensor; The exposed sensing layer includes a third flexible substrate disposed on the non-exposed sensing layer, and an exposed sensor disposed on the third flexible substrate and a lead wire corresponding to the exposed sensor; The lead wire is set to a curved pattern of any shape; The lead wires of each layer are extended to the interface of the multimodal sensor at the layer where the lead wires are located, and an exposure process is performed at the stepped position at the interface; Lead wires are prepared on the second flexible substrate and the third flexible substrate by the following method: A layer of metal chromium is deposited on the second flexible substrate and the third flexible substrate, wherein the thickness of the metal chromium is less than 15 nm; a lead wire of solid metal material is prepared on the metal chromium by a photolithography patterning process; or a lead wire of conductive liquid material is prepared on the metal chromium by a screen printing or inkjet printing process; the thickness of the lead wire is less than 300 nm; The flexible packaging layer covers the exposed sensing layer, and etches away the area directly above the exposed sensors, neural electrodes and electrical stimulators.

2. The multi-layer integrated flexible multimodal sensor according to claim 1, characterized in that: The pressure sensing layer, the non-exposed sensing layer and the exposed sensing layer of the multimodal sensor are arranged in a stepped shape at the interface of the multimodal sensor; and the gold fingers of the lead wires corresponding to each layer are arranged at each layer of the steps.

3. The multi-layer integrated flexible multimodal sensor according to claim 1, characterized in that: The exposed sensor includes a potassium and sodium ion sensor, an oxygen partial pressure sensor, a nerve electrode and an electrical stimulator; the potassium and sodium ion sensor and the oxygen partial pressure sensor adopt an embedded probe structure or a sensitive layer protruding probe structure; When the potassium and sodium ion sensors and the oxygen partial pressure sensor adopt an embedded probe structure, the third flexible substrate is the same as the second flexible substrate. The potassium and sodium ion sensors, oxygen partial pressure sensors, neural electrodes and electrical stimulators are all disposed on the third flexible substrate and are located Flexible substrate range.

4. The multi-layer integrated flexible multimodal sensor according to claim 3, characterized in that: When the potassium and sodium ion sensors and the oxygen partial pressure sensor adopt a sensitive layer protruding probe type structure, the third flexible substrate is In addition to the shape, it also includes a plurality of protruding probes made of the same material as the third flexible substrate, and the potassium and sodium ion sensors and the oxygen partial pressure sensor are arranged on the protruding probes; the plurality of protruding probes are arranged to avoid the multimodal sensor interface.

5. The multi-layer integrated flexible multimodal sensor according to claim 1, characterized in that: The first flexible substrate, the second flexible substrate and the third flexible substrate are made of the same or different substrate materials.

6. The multi-layer integrated flexible multimodal sensor according to claim 1, characterized in that: The first flexible substrate, the second flexible substrate and the third flexible substrate are made of photolithographic PI or SU-8; or non-photolithographic PI or Parylene.

7. The multi-layer integrated flexible multimodal sensor according to claim 1, characterized in that: The preparation process of the second flexible substrate and the third flexible substrate includes: Spin coating a flexible substrate material twice on the pressure sensing layer and the non-exposed sensing layer; Etching the flexible substrate material using an oxygen dry method to obtain the second flexible substrate and the third flexible substrate material which are flat; According to the component ratio of oxygen to carbon tetrafluoride of 1:1 by volume, the flat surfaces of the second flexible substrate and the third flexible substrate are etched by a plasma etching method to obtain the second flexible substrate and the third flexible substrate; the thickness of the flexible substrate is 7-10 μm.

8. The multi-layer integrated flexible multimodal sensor according to claim 1, characterized in that: The bottom size of the multimodal sensor is , thickness less than 300μm; The preparation process of the pressure sensor includes: Set the shape to be symmetrical. a first flexible substrate; Patterning 2n left-right symmetrical pressure sensitive film windows on the first flexible substrate, where n is the number of pressure sensors; Preparing an upper electrode plate and a lower electrode plate of a pressure sensor corresponding to the 2n pressure-sensitive film windows, and preparing a lead wire of the pressure sensor on the first flexible substrate; The first flexible substrate is folded in half along the symmetry axis so that the lower electrode plate is aligned and covered with the upper electrode plate, and a pressure sensor film is added in the middle to form a pressure sensor.

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