Bimodal flexible pressure sensing array and device

Abstract

The invention discloses a bimodal pressure sensor array and device.The bimodal pressure sensor array comprises a piezoelectric actuator, an elastic piezoresistive substrate array and a pressure sensor unit which are arranged from inside to outside, and the pressure sensor unit comprises a piezoelectric film array layer; the pressure measurement is realized based on the piezoelectric response of the piezoelectric film array layer and the vibration of the piezoelectric actuator; based on the piezoelectric response of the piezoelectric film array layer, the vibration of the piezoelectric actuator and the deformation of the elastic piezoresistive substrate array, the direction and angle measurement is realized. Pressure measurement and bending angle measurement can be simultaneously realized on a single device, and the unique dual-function sensing technology has huge application potential in the medical field.

Description

[0001] The present invention belongs to the field of piezoelectric sensors, and in particular relates to a dual-mode flexible pressure sensor array and device. Background Art

[0002] In recent years, flexible physical sensors that can measure and quantify the electrical signals generated by human activities have attracted the attention of many researchers due to their unique characteristics such as light weight, ultrathin, high flexibility, and stretchability. They can provide new development opportunities for human activity detection, personal healthcare, and medical treatment. In the past few decades, with the development of interfaces with human skin or organs, physiological measurement has always been a concern, and the research and development work in this field has been increasing day by day. All along, the diagnosis, treatment of many diseases, and the monitoring of human health are highly dependent on the physical signals of human vital signs. Pressure indicators inside the human body, such as intracranial pressure, pharyngeal pressure, cardiovascular and blood pressure, intervertebral disc pressure, plantar pressure, etc., are closely related to the operating state of human body functions, and many diseases externally show abnormal pressure changes. Therefore, accurately measuring the pressure inside the human body is of great significance for diagnosing certain diseases. Piezoelectric sensors, as devices that use the piezoelectric effect for information collection, that is, receive pressure signals from the outside world through the sensor, then convert these pressure signals into electrical signals, and finally process and analyze them by a computer to obtain corresponding data, play a crucial role in the pressure sensing system. Commonly used piezoelectric materials for pressure sensors include pbtio3, BaTiO3, PZT, ZnO, polypropylene (PP), PVDF, and P(VDF-TrFE), etc. Piezoresistive pressure sensors are based on the piezoresistive effect, which occurs when the resistance of a material changes with the applied pressure. These sensors have been widely studied by researchers due to their simple manufacturing process and device structure, low energy consumption during operation, easy pressure reading, and wide pressure detection range. Piezoresistive pressure sensors have broad prospects in realizing electronic skin and health monitoring due to their inherent flexibility, stretchability, and chemical stability. Moreover, they also have the advantages of simple manufacturing process and scalability. The active materials of piezoresistive pressure sensors are mainly based on elastomeric composites containing conductive fillers, such as R-GO, CNT, metal particles, and conductive polymers (CPs) incorporated into elastomers (such as PDMS and polyurethane (PU)) to produce the piezoresistive effect.

[0003] Traditional pressure sensors have only a single detection function in a single device. For example, a single pressure sensing unit can only detect the pressure signal covering the sensing unit and cannot simultaneously detect the pressure of a larger tissue area. At the same time, the pressures generated by different parts of the detected tissue on the sensor are different, and a single device cannot detect the different pressure signals generated at different positions. Therefore, it is very necessary and meaningful to fabricate a piezoelectric array capable of measuring different pressures at different positions in a single device. Ordinary pressure sensors can only detect the magnitude of the pressure exerted on them by external tissues. However, in the medical process, it is also equally important to detect what the surrounding tissues are. The present invention describes a method that utilizes the inverse piezoelectric effect of piezoelectric materials to actively apply pressure to biological tissues by the sensor and simultaneously obtain the signal exerted on the sensor by the reaction force to determine the surrounding biological tissues. At the same time, in different application scenarios, the physical signals to be detected are also different. For example, when the present invention is applied to the esophagus or intestine, while detecting the wall pressure, it is also necessary to detect the curvature of the esophagus or intestine and the size of the obstruction or tumor present in the esophagus or intestine. At this time, it is not sufficient for the device to only have the pressure detection function, and it also needs to have the bending angle detection function. Therefore, integrating a piezoelectric pressure sensor and a piezoresistive pressure sensor in one device has important research significance and broad application value. Summary of the Invention

[0004] The present invention solves the technical problem of how to simultaneously implement a pressure sensor and direction and angle measurement on one device; by combining the direct piezoelectric and inverse piezoelectric effects of piezoelectric materials and the sensing principle of piezoresistive materials, a unique sensor structure is constructed, which can simultaneously realize the detection of the human body wall pressure, the determination of the human body wall tissue, the measurement of the wall curvature, and the measurement of the size of foreign objects in the wall.

[0005] The technical solution adopted by the present invention is as follows: A dual-mode pressure sensor array, the dual-mode pressure sensor array includes a piezoelectric actuator, an elastic piezoresistive substrate array, and a pressure sensor unit arranged from the inside to the outside. The pressure sensor unit includes a piezoelectric thin film array layer, and realizes pressure measurement based on the piezoelectric response of the piezoelectric thin film array layer and the vibration of the piezoelectric actuator; realizes direction and angle measurement based on the piezoelectric response of the piezoelectric thin film array layer, the vibration of the piezoelectric actuator, and the deformation of the elastic piezoresistive substrate array.

[0006] Further, the pressure sensor unit further includes a flexible thin film base layer, a bottom electrode layer, a top electrode layer, and a packaging layer; the flexible thin film base layer, the bottom electrode layer, the piezoelectric thin film array layer, the top electrode layer, and the packaging layer are sequentially stacked.

[0007] Further, the piezoelectric actuation layer includes an actuation layer and a copper sheet arranged in a stacked manner. An elastic piezoresistive substrate array is arranged around the side of the copper sheet away from the actuation layer, and an elastic piezoresistive substrate array is arranged around the side of the actuation layer away from the copper sheet.

[0008] Further, the material of the piezoelectric thin film array includes, but is not limited to, one or several of PVDF, P(VDF-TrFE), quartz crystal, lithium niobate, piezoelectric ceramics, III-V group compounds, II-VI group compounds; the thickness is 25um - 50um.

[0009] Further, the electrodes of the bottom electrode layer and the top electrode layer are micro-nano printed onto the flexible thin film substrate layer and the piezoelectric thin film array layer. The materials of the electrodes of the bottom electrode layer and the top electrode layer include one of conductive silver paste, carbon nanotube solution, and graphene solution, and the thickness is 10um - 20um.

[0010] Further, the elastic piezoresistive substrate array includes an elastic substrate skeleton, a conductive material, an upper electrode, and a lower electrode. The material of the elastic substrate skeleton is one or more of PDMS, silica gel, epoxy resin glue, phenolic resin glue, polyacrylic resin glue, and polysilazane. The conductive material includes, but is not limited to, one or more of Ag, carbon nanotubes, and graphene. The upper electrode or the lower electrode is one of metal and its alloy electrode materials such as gold, platinum, aluminum, silver, copper, and magnesium.

[0011] Further, the encapsulation layer includes a flexible device protection layer. The material of the flexible device protection layer is one or more of PDMS, silica gel, epoxy resin glue, phenolic resin glue, polyacrylic resin glue, polysilazane, polyurethane sealant, and silicone sealant.

[0012] Further, the bottom electrode of the piezoelectric thin film array layer and the top electrode of the elastic piezoresistive substrate array are connected by a wire.

[0013] Further, the cross-section of the elastic piezoresistive substrate array includes one of cylindrical, circular, and elliptical.

[0014] A dual-mode pressure sensor device includes the dual-mode pressure sensor array described above, and also includes a signal processing device, a numerical display, and a pressure distribution display. The top electrode layer of the elastic piezoresistive substrate array and the bottom electrode layer of the piezoelectric thin film array layer are connected by silver paste to form a common electrode. The common electrode, the top electrode layer of the piezoelectric thin film array layer, and the bottom electrode layer of the elastic piezoresistive substrate array are respectively connected to the signal processing device. The signal processing device is connected to the numerical display and the pressure distribution display through signal transmission lines.

[0015] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are: 1. In the present invention, printing the electrodes and lead-out circuits of the piezoelectric sensitive layer using micro-nano printing technology can miniaturize and densify the units of the piezoelectric sensitive layer array, enabling more accurate measurement of the size information and softness of different parts of the object to be measured.

[0016] 2. The built-in piezoelectric actuation layer proposed in the present invention can increase the functions of the pressure measurement catheter. Ordinary pressure measurement catheters can only measure the magnitude of the pressure exerted on them by external objects and cannot measure the softness and hardness of external objects. The built-in piezoelectric actuation layer in the present invention applies pressure to the external object to enable the piezoelectric sensitive layer to obtain different feedbacks and thereby obtain the softness and hardness of the external object to be measured.

[0017] 3. In addition to being used to increase the deformation of the piezoelectric sensitive layer and thus increase the piezoelectric signal, the cylindrical elastic piezoresistive substrate array mentioned in the present invention can also be filled with conductive factors inside it to make it a piezoresistive sensor for measuring the bending direction and angle of the pressure measurement hose.

[0018] 4. Combining tissue pressure measurement, hose bending angle measurement, and obstacle size measurement has important application potential in biological tissue pressure measurement and disease prevention.

[0019] 5. The device is provided with a numerical display and a pressure distribution display after passing through the signal processing device, and the measurement results can be seen very intuitively. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of an embodiment of the present invention; Figure 2 is an expanded view of the pressure sensing unit array of an embodiment of the present invention; Figure 3 is a structural diagram of the pressure sensing unit of an embodiment of the present invention; Figure 4 is a schematic diagram of the working process for measuring the elasticity of biological tissue of an embodiment of the present invention; Figure 5 is a system framework diagram for measuring the pressure of external biological tissue and the bending angle inside a biological pipeline of an embodiment of the present invention.

[0021] Reference numerals: 1 - piezoelectric actuation layer, 2 - copper plate, 3 - cylindrical elastic piezoresistive substrate array, 4 - pressure sensing unit, 5 - flexible thin film base layer, 6 - bottom electrode layer of the piezoelectric film array, 7 - piezoelectric film array layer, 8 - top electrode layer of the piezoelectric film array, 9 - encapsulation layer, 10 - common electrode, 11 - bottom electrode layer of the cylindrical elastic piezoresistive substrate array, 12 - signal processing device, 13 - numerical display, 14 - pressure distribution display. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] A dual-mode pressure sensor array, which includes a piezoelectric actuator, an elastic piezoresistive substrate array, and a pressure sensor unit arranged from the inside out. The pressure sensor unit includes a piezoelectric thin film array layer. Pressure measurement is achieved based on the piezoelectric response of the piezoelectric thin film array layer and the vibration of the piezoelectric actuator; direction and angle measurement are achieved based on the piezoelectric response of the piezoelectric thin film array layer, the vibration of the piezoelectric actuator, and the deformation of the elastic piezoresistive substrate array.

[0023] The pressure sensor unit further includes a flexible thin film base layer, a bottom electrode layer, a top electrode layer, and a packaging layer; the flexible thin film base layer, the bottom electrode layer, the piezoelectric thin film array layer, the top electrode layer, and the packaging layer are stacked in sequence.

[0024] The piezoelectric actuator layer includes a stacked actuator layer and a copper sheet. The elastic piezoresistive substrate array is arranged around the side of the copper sheet away from the actuator layer, and the elastic piezoresistive substrate array is also arranged around the side of the actuator layer away from the copper sheet.

[0025] The material of the piezoelectric thin film array includes, but is not limited to, one or several of PVDF, P(VDF-TrFE), quartz crystal, lithium niobate, piezoelectric ceramics, III-V compounds, II-VI compounds; the thickness is 25um - 50um.

[0026] The electrodes of the bottom electrode layer and the top electrode layer are micro-nano printed onto the flexible thin film base layer and the piezoelectric thin film array layer. The materials of the electrodes of the bottom electrode layer and the top electrode layer include one of conductive silver paste, carbon nanotube solution, and graphene solution, and the thickness is 10um - 20um.

[0027] The elastic piezoresistive substrate array includes an elastic substrate skeleton, a conductive material, an upper electrode, and a lower electrode. The material of the elastic substrate skeleton is one or more of PDMS, silica gel, epoxy resin glue, phenolic resin glue, polyacrylic resin glue, and polysilazane. The conductive material includes, but is not limited to, one or more of Ag, carbon nanotubes, and graphene. The upper electrode or the lower electrode is one of metal and its alloy electrode materials such as gold, platinum, aluminum, silver, copper, and magnesium.

[0028] The packaging layer includes a flexible device protection layer, and the material of the flexible device protection layer is one or more of PDMS, silica gel, epoxy resin glue, phenolic resin glue, polyacrylic resin glue, polysilazane, polyurethane sealant, and silicone sealant.

[0029] The bottom electrode of the piezoelectric thin film array layer is connected to the top electrode of the elastic piezoresistive substrate array through a wire.

[0030] The cross-section of the elastic piezoresistive substrate array includes one of cylindrical, circular, and elliptical.

[0031] A dual - mode pressure sensor device includes the dual - mode pressure sensor array, and also includes a signal processing device, a numerical display, and a pressure distribution display. The top electrode layer of the elastic piezoresistive substrate array and the bottom electrode layer of the piezoelectric thin - film array layer are connected by silver paste to form a common electrode. The common electrode, the top electrode layer of the piezoelectric thin - film array layer, and the bottom electrode layer of the elastic piezoresistive substrate array are respectively connected to the signal processing device. The signal processing device is connected to the numerical display and the pressure distribution display through signal transmission lines.

[0032] Specifically, a dual - mode pressure sensor array and device with pressure measurement and bending angle measurement functions, as Figure 1 shown, includes a piezoelectric actuator layer 1, a copper sheet 2, a cylindrical elastic piezoresistive substrate array 3, a pressure sensing unit 4. The pressure sensing unit 4 includes (a flexible thin - film base layer 5, a bottom electrode layer 6, a piezoelectric thin - film array layer 7, a top electrode layer 8, a packaging layer 9), a common electrode 10, a bottom electrode layer 11 of the cylindrical elastic piezoresistive substrate array, a signal processing device 12, a numerical display 13, and a pressure distribution display 14. When a measured object applies pressure to the piezoelectric thin - film array layer, it drives the bottom electrode layer 11 of the cylindrical elastic piezoresistive substrate array to deform. The piezoelectric thin - film array layer (PVDF) 7 generates a larger deformation compared to when no elastic base layer is added, generating a more obvious signal. When an alternating voltage is applied to the piezoelectric actuator layer (PZT) 1, its vibration deformation drives the deformation of the PDMS elastic base layer, which in turn drives the piezoelectric thin - film array layer (PVDF) 7 to apply pressure to the outside. The external measured object applies a reaction force to it, causing it to deform, and thus obtaining the soft - hardness information of different materials. When the pressure - measuring hose encounters an obstacle or the pipeline bends, it drives the bottom electrode layer 11 of the cylindrical elastic piezoresistive substrate array to deform. By measuring the resistance values of different units, the deformation amounts of different units are obtained, and then the bending angle and direction are obtained, and the size information of the obstacle and the bending degree information of the pipeline are obtained.

[0033] The constructed device structure is specifically as follows: The piezoelectric actuator is composed of a 1-mm PZT and a metal copper plate. Ag electrodes with a thickness of 50 nm are deposited on both surfaces of the PZT. The cylindrical elastic piezoresistive substrate array 3 is made by filling cylindrical sugar cube modules with PDMS with a ratio of PDMS main agent to PDMS cross-linking agent of 10:1 to form a cylindrical PDMS skeleton and then filling it with a carbon nanotube solution so that conductive factors adhere to the skeleton. The flexible thin-film base layer 5 is a PI film with a thickness of 50 μm. The bottom electrode 6 and the bottom electrode lead-out circuit use micro-nano printing technology to print conductive silver paste on the flexible thin-film base layer. After annealing, the conductive silver paste forms a 5-μm-thick film. The piezoelectric thin-film array layer 7 consists of 8 PVDF thin-film units with a thickness of 30 μm, which are fixed above the bottom electrode. Micro-nano printing technology is used to print conductive silver paste on the upper surfaces of the 8 PVDF thin films to form the top electrode and the top electrode lead-out circuit. After annealing, an Ag electrode with a thickness of 5 μm is formed. Micro-nano printing technology is used to print PDMS solution on the upper surface of the piezoelectric thin-film array layer and the printed circuit for encapsulation. After printing and annealing, an encapsulation film with a thickness of 50 μm is formed. Then, the top electrode layer of the cylindrical elastic piezoresistive substrate array and the bottom electrode layer 6 of the piezoelectric thin-film array are connected together by silver paste to form a common electrode 10. The common electrode 10, the top electrode layer 8 of the piezoelectric thin-film array, and the bottom electrode layer 11 of the cylindrical elastic piezoresistive substrate array are respectively connected to the signal processing device 12, and the signals of the signal processing device are connected to the numerical display 13 and the pressure distribution display 14 using signal transmission lines. For the dual-mode pressure sensing device, the device is arranged in sequence as: piezoelectric actuator, cylindrical elastic piezoresistive substrate array, flexible thin-film base layer, electrode array, piezoelectric thin-film array, electrode array, flexible device protective layer. A signal processing device, a numerical display, and a pressure distribution display are arranged at the rear end of the device. When an external biological tissue applies pressure to the piezoelectric thin-film array layer, the piezoelectric thin-film array layer generates a piezoelectric response. When the piezoelectric actuator deforms externally, the reaction force of the external biological tissue is applied to the piezoelectric thin-film array to generate a piezoelectric response. The piezoresistive device is arranged in the middle of the device. The piezoresistive devices are arranged in a cylindrical shape in a clockwise direction in 8 arrays. When the flexible hose is squeezed by an obstacle, the piezoresistive devices deform and transmit the magnitude of the deformation amount outwards, thereby obtaining the bending direction and angle of the hose. The described piezoelectric device with a pressure detection function and a function of deforming externally to apply pressure combines the direct piezoelectric effect and the inverse piezoelectric effect of piezoelectric materials. When an external tissue applies pressure to the piezoelectric thin-film array, the piezoelectric thin-film array deforms on the cylindrical elastic substrate, and the piezoelectric thin-film array generates a direct piezoelectric signal, generating charges with equal magnitudes and opposite directions on both sides of the piezoelectric thin film, thereby generating a voltage signal.When an alternating current is applied to the piezoelectric actuator by the user, the piezoelectric actuator deforms due to the inverse piezoelectric effect of the material. Since an alternating current is applied, vibrations are generated, exerting pressure on the cylindrical elastic substrate and then transmitted to the piezoelectric thin film array layer and the biological tissue. The biological tissue exerts a reaction force on the piezoelectric thin film array layer, and the piezoelectric thin film array layer generates a positive piezoelectric signal. Since the Young's moduli of different biological tissues are different, the magnitudes of the reaction forces applied to the piezoelectric thin film layer are also different, resulting in different piezoelectric responses. The piezoresistive sensor array that can detect the bending angle of the hose and the size of the obstacle encountered is the elastic piezoresistive substrate array. It combines the deformation of the device under the pressure of an external force, which leads to the change in the distribution density and contact state of the internal conductive material, and further causes a regular change in the resistance of the device. When the human body pipeline bends in a specific direction, specific sensors in the piezoresistive array undergo different deformations, and the distribution density and contact state of the internal conductive material change to different degrees. By measuring the resistance of the piezoresistive sensor, the bending direction and angle inside the human body pipeline can be obtained. When encountering obstacles of different sizes, including but not limited to tumors and obstructions, the bending degrees of the hose are different. By combining the entry distance and bending angle of the hose, the contour and size of the obstacle can be obtained.

[0034] Generally, the electromechanical energy conversion of piezoelectric materials is to convert mechanical energy into electrical energy. Theoretically, when an external force is applied in the direction normal to the surface of the piezoelectric material, piezoelectric induced charges will accumulate on both sides due to the deformation of the piezoelectric material. The open-circuit voltage and short-circuit current generated can be calculated by the following formulas:

[0035] Furthermore, for tissue modulus values between 1 kPa and 1000 kPa, a scaling law related to the tissue modulus Etissue and the sensor voltage Vsensor can be established.

[0036] Under standard test conditions, elastic components with different Young's moduli are fabricated by configuring solutions with different ratios of PDMS base agent and cross-linking agent to simulate tissues that a piezoelectric sensor may test. The magnitude of the applied force is adjusted by regulating the travel distance of the horizontal motor used for testing, thereby obtaining the piezoelectric characteristics of the pressure sensing unit 4. When testing a piezoresistive array with a bending angle measurement function, semi-circular models with different curvatures are customized, and the piezoresistive array is pressed against the semi-circular model to change its bending angle. The piezoresistive array reflects the change in the bending angle through the change in the sensor resistance value. Voltages with different magnitudes and frequencies are applied to the piezoelectric actuator layer 1, and different characteristic signals obtained after the sensor applies forces to elastic structures with different Young's moduli are measured, thereby judging different elastic tissues. The numerical display 13 shows the signal numerical magnitudes of different units in the array, and the pressure distribution display 14 visually shows the pressure distribution by displaying different colors.

[0037] Specifically, the sensitivity is 40.2 mv / N, the maximum output power at a 70 MΩ load is 0.122 uW / cm2, and during 1000 cyclic impact experiments, the output of the piezoelectric voltage signal only decreases by 6.8%. When testing a piezoresistive array with a bending angle measurement function, semi-circular models with different curvatures are customized, and the piezoresistive array is pressed against the semi-circular model to change its bending angle. Under standard test conditions, the bending response time is less than 67 ms, and the piezoresistive array reflects the change in the bending angle through the change in the sensor resistance value. Specifically, the slope of the approximate relationship line between the resistance value of the sensor and the curvature is 3.014, and the resistance value of the sensor changes significantly after 2000 cycles of use. After applying an alternating current with a voltage of 20 V and a frequency of 220 HZ to the piezoelectric actuator layer 1, the pressure sensing unit 4 generates a voltage of approximately 0.5 mv under a pressure of 80 KPa, and the pressure sensing unit 4 generates a voltage of approximately 0.57 mv under a pressure of 80 Kpa.

[0038] On the basis of Example 1, using the same preparation process and keeping other factors unchanged, in order to explore the sensitivity and signal quality of different piezoelectric sensitive materials to biological tissues, the piezoelectric thin film array layer 7 used is replaced with a P(VDF-TrFE) thin film. Other parts of this example are the same as those of the above example and will not be elaborated here.

[0039] Under standard test conditions, elastic components with different Young's moduli were fabricated by configuring solutions with different ratios of PDMS base agent and cross-linking agent to simulate tissues that a piezoelectric sensor might test. The magnitude of the applied force was adjusted by regulating the travel distance of the horizontal motor used for testing, thereby obtaining the piezoelectric characteristics of the pressure sensing unit 4, which were specifically manifested as follows: the sensitivity was 52.2 mv / N, the maximum output power at a 70 MΩ load was 0.242 uW / cm2, and during 1000 cyclic impact experiments, the output of its piezoelectric voltage signal decreased by only 6.5%. When testing a piezoresistive array with a bending angle measurement function, semicircular models with different curvatures were customized, and the piezoresistive array was pressed against the semicircular model to change its bending angle. Under standard test conditions, the bending response time was less than 67 ms. The piezoresistive array reflected the change in the bending angle through the change in the resistance value of the sensor, which was specifically manifested as follows: the slope of the approximate relationship line between the resistance value of the sensor and the curvature was 3.014, and the resistance value of the sensor changed significantly after 2000 cycles of use. After applying an alternating current with a voltage of 20 V and a frequency of 220 HZ to the piezoelectric actuator layer 1, a voltage of approximately 0.5 mv was generated in the pressure sensing unit 4 under a pressure of 80 KPa, and a voltage of approximately 0.57 mv was generated in the pressure sensing unit 4 under a pressure of 80 Kpa.

[0040] Specific Example 3: On the basis of Example 1, the same preparation process was adopted and other factors were kept unchanged. In order to explore the influence of the deformation amount generated by different biological tissues on the sensing device on the signal quality generated by the piezoelectric thin film array layer 7, the ratio of the PDMS base agent and the cross-linking agent of the PDMS solution used to fabricate the PDMS elastic base layer was changed to 20:1, making it a material with higher elasticity, changing the piezoresistive characteristics of the piezoresistive array and simultaneously changing the deformation amount of the piezoelectric thin film array layer 7. Other parts of this example are the same as those of the above example and will not be elaborated here.

[0041] Specific Example 4: On the basis of Example 1, the same preparation process was adopted and other factors were kept unchanged. In order to explore the sensitivity and signal quality of angle measurement of piezoresistive sensors with different conductivities, the concentration of the carbon nanotube solution used when fabricating the piezoresistive array was changed from 0.35 wt% to 0.45 wt%, making its conductivity better. Other parts of this example are the same as those of the above example and will not be elaborated here.

[0042] Specific Example 5: On the basis of Example 1, the same preparation process was adopted and other factors were kept unchanged. In medical experiments, it is necessary to ensure that the device does not damage biological tissues, so there are extremely high requirements for the device size. In this example, in order to explore the influence of different packaging materials on the device size and the device's effect on external biological tissues, the packaging material in Example 1 was replaced with polydimethylsiloxane. Other parts of this example are the same as those of the above example and will not be elaborated here.

Claims

1. A dual-modal pressure sensor array, characterized in that: The dual-mode pressure sensor array includes a piezoelectric actuator, an elastic piezoresistive substrate array, and a pressure sensor unit arranged from the inside out. The pressure sensor unit includes a piezoelectric thin film array layer, and pressure measurement is achieved based on the piezoelectric response of the piezoelectric thin film array layer and the vibration of the piezoelectric actuator. Direction and angle measurement are achieved based on the piezoelectric response of the piezoelectric thin film array layer, the vibration of the piezoelectric actuator, and the deformation of the elastic piezoresistive substrate array.

2. The dual-mode pressure sensor array according to claim 1, wherein: The pressure sensor unit further includes a flexible thin film base layer, a bottom electrode layer, a top electrode layer, and a packaging layer; the flexible thin film base layer, the bottom electrode layer, the piezoelectric thin film array layer, the top electrode layer, and the packaging layer are sequentially stacked.

3. The dual-mode pressure sensor array according to claim 1, wherein: The piezoelectric actuation layer includes a stacked actuation layer and a copper sheet. The elastic piezoresistive substrate array is disposed around the side of the copper sheet away from the actuation layer, and the elastic piezoresistive substrate array is disposed around the side of the actuation layer away from the copper sheet.

4. A dual-modal pressure sensor array according to claim 1, wherein: The material of the piezoelectric thin film array includes, but is not limited to, one or several of PVDF, P(VDF-TrFE), quartz crystal, lithium niobate, piezoelectric ceramics, III-V compounds, II-VI compounds; the thickness is 25um - 50um.

5. A dual-modal pressure sensor array according to claim 2, characterized in that: The electrodes of the bottom electrode layer and the top electrode layer are micro-nano printed onto the flexible thin film base layer and the piezoelectric thin film array layer. The materials of the electrodes of the bottom electrode layer and the top electrode layer include one of conductive silver paste, carbon nanotube solution, and graphene solution, and the thickness is 10um - 20um.

6. A dual-modal pressure sensor array according to claim 1, characterized in that: The elastic piezoresistive substrate array includes an elastic substrate skeleton, a conductive material, an upper electrode, and a lower electrode. The material of the elastic substrate skeleton is one or more of PDMS, silica gel, epoxy resin glue, phenolic resin glue, polyacrylic resin glue, and polysilazane. The conductive material includes, but is not limited to, one or more of Ag, carbon nanotubes, and graphene. The upper electrode or the lower electrode is one of metal and its alloy electrode materials such as gold, platinum, aluminum, silver, copper, and magnesium.

7. The dual-mode pressure sensor array according to claim 2, wherein: The packaging layer includes a flexible device protection layer, and the material of the flexible device protection layer is one or more of PDMS, silica gel, epoxy resin glue, phenolic resin glue, polyacrylic resin glue, polysilazane, polyurethane sealant, and silicone sealant.

8. A dual-mode pressure sensor array according to claim 1, characterized in that: The bottom electrode of the piezoelectric thin film array layer and the top electrode of the elastic piezoresistive substrate array are connected by a wire.

9. The dual-mode pressure sensor array according to claim 1, wherein: The cross-section of the elastic piezoresistive substrate array includes one of cylindrical, circular, and elliptical.

10. A dual-mode pressure sensor device, characterized in that: Including the dual-mode pressure sensor array according to any one of claims 1-9, further including a signal processing device, a numerical display, and a pressure distribution display. The top electrode layer of the elastic piezoresistive substrate array and the bottom electrode layer of the piezoelectric thin film array layer are connected by silver paste to form a common electrode. The common electrode, the top electrode layer of the piezoelectric thin film array layer, and the bottom electrode layer of the elastic piezoresistive substrate array are respectively connected to the signal processing device. The signal processing device is connected to the numerical display and the pressure distribution display through a signal transmission line.

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