CN117309197A

CN117309197A - Pressure sensor based on heat conduction mechanism

Info

Publication number: CN117309197A
Application number: CN202310782779.6A
Authority: CN
Inventors: 于宏宇; 王晓毅; 邓洋
Original assignee: Hong Kong University of Science and Technology HKUST
Current assignee: Hong Kong University of Science and Technology HKUST
Priority date: 2022-06-29
Filing date: 2023-06-29
Publication date: 2023-12-29

Abstract

The present disclosure relates to a pressure sensor, comprising: a carrier; a thermal sensing membrane on the carrier and comprising at least one heat detector configured to produce a temperature change in response to being subjected to pressure such that a current in the at least one heat detector changes in response to the temperature change; a processor is connected to the heat detector of the heat sensing diaphragm and configured to detect the pressure from a change in the current.

Description

Pressure sensor based on heat conduction mechanism

Technical Field

The present disclosure relates to the field of sensors, and more particularly, to a pressure sensor and a method of manufacturing the same.

Background

Among the various types of sensors developed, pressure sensors can impart tactile sensing capabilities to a machine and play an important role in electronics. In recent years, high-performance pressure sensors are widely applied in the fields of touch screens, wearable electronic devices, human-computer interfaces, real-time physiological signal sensing and the like, and are attracting extensive research attention in the fields of wearable electronic devices and intelligent electronic skin.

However, because the "functionality" of the sensor is generally incompatible with "simple" manufacturing strategies, the sensor is hardly capable of meeting both low cost targets and good performance requirements. To date, a great deal of work has been done in various ways to improve the performance of pressure sensors. Pressure sensing mechanisms can be categorized into many categories, such as piezoelectric sensors, capacitive sensors, resistive sensors, triboelectric sensors, and the like, according to the test principle.

The present invention proposes a simple and low-cost Thermal Resistance Pressure Sensor (TRPS) based on a thermally conductive sensing mechanism. The device consists of a thermal sensing unit, a carrier and an elastomer. The pressure value may be converted by the elastomer deformation and monitored by heat loss from the thermal sensing unit. Based on this we produced prototypes with excellent properties that can be used for mass production and that facilitate the use of pressure sensors in wearable electronics and human-machine interfaces.

Disclosure of Invention

In one aspect, there is provided a pressure sensor comprising: a carrier; a thermal sensing membrane on the carrier and comprising at least one heat detector configured to produce a temperature change in response to being subjected to pressure such that a current in the at least one heat detector changes in response to the temperature change; a processor is connected to the heat detector of the heat sensing diaphragm and configured to detect the pressure from a change in the current.

In one embodiment, the thermal sensing film has a sensing region including a central region in which a protective layer is formed, a circular shape surrounding the central region, and a pad region surrounding the sensing region, the at least one thermal detector including a plurality of thermal detectors uniformly distributed in the sensing region at equal intervals, a plurality of pads forming the pads and being electrically connected in one-to-one correspondence with the plurality of thermal detectors, respectively.

In one embodiment, the pressure sensor further comprises an elastomer located above the thermal sensing membrane, wherein the elastomer is deformed by pressure such that the elastomer presses at least a portion of the plurality of thermal detectors, the elastomer being out of contact with the plurality of thermal detectors in response to being not under pressure.

In one embodiment, the front projection of the elastomer onto the thermal sensing membrane overlaps with the front projections of the plurality of thermal detectors onto the thermal sensing membrane.

In one embodiment, the elastomer has a planar upper surface remote from the thermal sensing membrane and a curved surface protruding toward the thermal sensing membrane, and an orthographic projection of the planar upper surface of the elastomer onto the thermal sensing membrane is circular.

In one embodiment, the elastomer comprises silica gel, and the thickness of the elastomer is 5mm.

In one embodiment, the plurality of heat detectors are equally spaced, circumferentially distributed outside the central region.

In one embodiment, each of the plurality of heat detectors has a fan-shaped planar coil structure in which conductive wires are routed in an S-shape, the plurality of heat detectors being equally spaced from a center point of the central region, respective edges of the plurality of heat detectors near the central region being on the same circumference, and respective edges of the plurality of heat detectors far from the central region being on the same circumference.

In one embodiment, the plurality of heat detectors are arranged in a plurality of rows and columns in a heat detector array.

In one embodiment, each of the plurality of heat detectors has a concentric circular planar coil structure formed by winding a conductive wire in a clockwise or counterclockwise direction.

In one embodiment, the elastomer includes an array of elastomers positioned above the thermal sensing membrane and including a plurality of elastomers arranged in a plurality of rows and columns, at least a portion of the plurality of elastomers being deformed by pressure such that the portion of the elastomers presses against a respective thermal detector of the plurality of thermal detectors, the plurality of elastomers being out of contact with the plurality of thermal detectors in response to being not being under pressure.

In one embodiment, the front projection of each elastomer onto the thermal sensing membrane overlaps with the front projection of the corresponding thermal detector onto the thermal sensing membrane.

In one embodiment, each elastomer has a planar upper surface remote from the thermal sensing membrane and a curved surface protruding toward the thermal sensing membrane, and the orthographic projection of the planar upper surface of each elastomer onto the thermal sensing membrane is circular.

In one embodiment, the conductive wire comprises one of a metal wire made of titanium tungsten and platinum, a carbon-based conductor, and indium tin oxide.

In one embodiment, the carrier comprises a flexible material.

In another aspect, a braille recognition device is provided, including the above pressure sensor.

In yet another aspect, a method of making a pressure sensor is provided, comprising: providing a carrier; forming a thermal sensing film comprising at least one heat detector on the carrier, wherein the heat detector is configured to produce a temperature change in response to being subjected to pressure such that a current in the at least one heat detector changes in response to the temperature change; a processor is provided that is connected to the heat detector of the heat sensing diaphragm and configured to detect the pressure from a change in the current.

In one embodiment, forming a thermal sensing membrane comprising at least one thermal detector on the carrier comprises: depositing a protective layer on the substrate using a chemical vapor deposition process; sputtering to form a titanium tungsten layer on the protective layer; forming a platinum layer on the titanium tungsten layer by sputtering to form a plurality of heat detectors in a sensing region and a plurality of bonding pads in a bonding pad region; forming a protective layer on the plurality of heat detectors and the plurality of pads such that the protective layer covers the plurality of heat detectors and the plurality of pads; etching the protective layer in the pad region until the plurality of pads are exposed while retaining the protective layers in the central region and the sensing region; stripping the substrate from the patterned protective layer, thereby forming the thermal sensing film; the thermal sensing membrane is attached to the carrier.

In one embodiment, the method further comprises: forming an elastomer composed of silica gel using a mold; encapsulating the elastomer, the thermal sensing film, and the carrier.

Drawings

Fig. 1 illustrates a perspective view of a pressure sensor according to one embodiment of the present disclosure.

FIG. 2 illustrates a perspective view of a pressure sensor according to one embodiment of the present disclosure

Fig. 3 illustrates a plan view of a pressure sensor according to one embodiment of the present disclosure.

Fig. 4 illustrates a state of a pressure sensor when a force is applied according to one embodiment of the present disclosure.

Fig. 5 illustrates a state of a pressure sensor when a force is applied according to one embodiment of the present disclosure.

Fig. 6A-6D illustrate current flow in respective heat detectors in accordance with one embodiment of the present disclosure.

Fig. 7A to 7I illustrate a manufacturing process of a pressure sensor according to an embodiment of the present disclosure.

Fig. 8 illustrates a top view of an elastomer according to one embodiment of the present disclosure.

FIG. 9 illustrates a top view of a thermal sensing film according to one embodiment of the present disclosure.

Fig. 10 illustrates a perspective view of a pressure sensor according to one embodiment of the present disclosure.

FIG. 11 illustrates a plan view of a heat detector array according to one embodiment of the present disclosure.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present disclosure, the present disclosure will be described in further detail with reference to the accompanying drawings and detailed description.

The present disclosure will be described in more detail below with reference to the accompanying drawings. Like elements are denoted by like reference numerals throughout the various figures. For purposes of clarity, the various features of the drawings are not drawn to scale. Furthermore, some well-known portions may not be shown in the drawings.

Numerous specific details of the present disclosure, such as construction, materials, dimensions, processing techniques and technologies, are set forth in the following description in order to provide a more thorough understanding of the present disclosure. However, as will be understood by those skilled in the art, the present disclosure may be practiced without these specific details.

Typically, the pressure component or shear force component of the pressure changes the capacitance of the parallel plate capacitor by changing the effective overlap area of the parallel plate capacitor and the distance between the two plates. For example, a capacitive pressure sensor for human physiological signal acquisition is reported that has a minimum detection limit of 1.5Pa, a broad measurement range (0-400 kPa), and high reliability at high pressure (> 167 kPa) exceeding 10000 cycles. Robust flexible capacitive pressure sensors with PDMS embedded silver nanowires have also been reported to have fast response times, good repeatability and good stability. However, it is difficult for the capacitive pressure sensor to obtain high sensitivity in a high voltage range due to the limit of young's modulus of the elastic insulating layer.

Piezoelectric pressure sensors rely on a piezoelectrically sensitive material that can convert mechanical energy into electrical energy such that when the material is deformed by an external force, a potential difference is created across two opposing surfaces of the material. For example, a Polydopamine (PDA) modification strategy has been reported, combining PDA with piezoelectric materials of barium titanate (BaTiO 3, BTO) and polyvinylidene fluoride (PVDF), to promote diffusion of Barium Titanate (BTO) into polyvinylidene fluoride (PVDF) matrix, the novel design achieving a fast response of 61ms and a significant output voltage of 9.3V. Another piezoelectric material of lead zirconate titanate (PZT) Nanofibers (NF) in Polydimethylsiloxane (PDMS) has also been proposed. The flexible piezoelectric pressure sensor exhibits a wide linear range (1.25-250 kPa), good reproducibility over 2000 cycles, and potential applications for human motion monitoring. A new approach has also been proposed to improve the dielectric and piezoelectric properties of ceramic-epoxy nanocomposites with additional small amounts of CNT dispersion. The optimum concentration of CNT filler was 0.07% by mass and the output voltage increased significantly to 575.42mV at 1N.

Piezoresistive pressure sensorAnd measuring external force, wherein the external force can change the distribution and contact state of the internal conductive material, thereby leading to the resistance value of the composite material. Piezoresistive pressure sensors have the advantage of a less complex sensor structure, low power consumption and a wide measuring range compared to capacitive pressure sensors and piezo-electric pressure sensors. A piezoresistive pressure sensor made of flexible Carbonized Crepe Paper (CCP) with corrugated structure is proposed, which shows high performance, including high sensitivity (at 0-2.53kPa ^-1 To 2.56-5.67kPa ^-1 ) A wide applicable pressure range (0-20 kPa), a fast response time (about 30 ms), a low detection limit (about 90 Pa) and good durability (> 3000 cycles). An ultrasensitive piezoresistive pressure sensor based on the conductive polymer elastic membrane sensed by the hollow sphere microstructure is also reported, and can detect the pressure below 1Pa, and has good repeatability. Sensors of the above type rely on external power converters, otherwise these sensors cannot operate.

Triboelectric-based pressure sensors are active sensors that convert a mechanical input into an electrical output without the need for an external power source, which is known as self-powered. An array of triboelectrically active sensors for pressure detection is proposed, which has a high sensitivity (0.31 kPa ^-1 ) Steel trap response time (< 5 ms), repeatability (30000 cycles), low detection limit (2.1 Pa). To achieve better performance, major research efforts have been focused on material engineering or surface microstructure to improve sensitivity, response time, and long-term stability, which typically involve expensive micromachining processes or complex procedures. Furthermore, these devices mainly use some chemical synthesis procedures, which are generally not ecologically friendly.

The present disclosure provides a thermal resistance pressure sensor that is simple to manufacture and low in cost. The pressure detection mechanism is based on thermal conduction, and deformation of the elastomer will result in thermal loss of the resistor and resistance change of the thermal detector. By optimizing the shape and material of the elastomer, a wide linear measurement range and a low detection limit can be achieved. The manufactured prototype has good repeatability, high linearity, quick response and good stability. The pressure sensor of the present disclosure has the advantage of high stability, low power consumption, and is compatible with silicon-based rigid substrates, elastomers, and flexible membranes, as compared to other pressure sensors.

Fig. 1 illustrates a perspective view of a pressure sensor according to one embodiment of the present disclosure. As shown in fig. 1, the pressure sensor includes a carrier 7, a thermal sensing membrane 1, and a processor. The carrier 7 includes, but is not limited to, flexible materials, such as PET, PC, PVC, ABS, PE, PI, etc., and the carrier 7 may also employ a rigid substrate, such as a wafer, plastic sheet, glass, etc. The thermal sensing membrane 1 is located on a carrier 7. The thermal sensing film 1 includes a central region R1, a sensing region R2 annularly surrounding the central region R1, and a pad region R3 annularly surrounding the sensing region R2. A protective layer of parylene-C is provided in the central region R1. A plurality of heat detectors, for example, eight heat detectors TD1 through TD8, are equally spaced, circularly distributed in the sensing region R2. A plurality of pads, for example, eight pads, are equally spaced, circularly distributed in the pad region R3. The plurality of heat detectors are electrically connected to the plurality of pads in one-to-one correspondence, and the plurality of heat detectors TD1 to TD8 are connected in parallel. A processor is connected to the thermal sensing membrane and configured to detect the pressure from a temperature change of the thermal sensing membrane. In the example shown in fig. 1, skin (e.g., finger or electronic skin) contacts at least one of the heat detectors TD1 through TD8, changing the contact area with the heat detector, resulting in a loss of thermal energy and thus a temperature change. A processor detects the pressure from a temperature change of the thermal sensing membrane.

Fig. 2 illustrates a perspective view of a pressure sensor according to one embodiment of the present disclosure. As shown in fig. 2, the pressure sensor includes a thermal sensing membrane 1 having a plurality of heat detectors, an elastic body 2, a carrier 7, and a processor. The pressure sensor shown in fig. 2 is basically the same in structure as the pressure sensor shown in fig. 1, except that: the pressure sensor shown in fig. 2 further comprises an elastomer 2. The elastic body 2 has a planar upper surface S1 distant from the heat sensing film 1 and a curved surface S2 (i.e., a spherical surface S2) close to the heat sensing film 1. The orthographic projection of the planar upper surface S1 of the elastic body on the thermal sensing film 1 is circular.

The front projection of the elastic body 2 on the thermal sensing film 1 in fig. 2 covers the central region R1 and a part of the sensing region R2 and does not exceed the range of the sensing region R2. The front projection of the elastic body 2 on the heat sensing film 1 overlaps a portion of the front projection of each of the plurality of heat detectors on the heat sensing film 1. In one embodiment, the orthographic projection of the elastic body 2 on the thermal sensing film 1 overlaps the central region R1, overlaps a portion of the sensing region R2, and does not overlap the pad region R3.

As shown in fig. 2, in the absence of pressure, the curved surface S2 of the elastic body 2 is in direct contact with the central region R1 of the thermal sensing film 1, thereby avoiding the dislocation of the elastic body 2 and the thermal sensing film 1 to affect the product performance. As shown in fig. 2, in the absence of pressure, the elastic body 2 having the inverted convex surface is not deformed, the elastic body 2 is not in contact with any one of the heat detectors on the heat sensing film 1, and the circularly allocated heat detectors TD1, TD2, TD3, TD4 are not subjected to temperature change.

Fig. 3 illustrates a plan view of a pressure sensor according to one embodiment of the present disclosure. Each heat detector has a fan-shaped annular planar coil structure in which conductive wires are routed in an S-shape. The edges of the plurality of heat detectors near the central region R1 are on the same circumference, and the edges of the plurality of heat detectors far from the central region R1 are also on the same circumference. The plurality of heat detectors are equidistant from the center point of the central region R1. The structure of the heat detectors may not be limited thereto, and may be designed according to practical circumstances, for example, each heat detector has a circular planar coil structure, a square planar coil structure.

A signal is input to each of the heat detectors TD1 to TD8 on the heat sensing film 1 via the signal input line W1 such that the temperature of the heat detectors TD1 to TD8 is at a high temperature (T) compared to the ambient temperature (Ta). A signal input line W1 is provided between each two adjacent heat detectors of the heat sensing film 1. Each heat detector is electrically connected to a corresponding pad via one of the signal output lines W2, so that a sensing signal is transmitted to the corresponding pad via the signal output line W2, so that it is received by the processor for signal processing. A signal output line W2 is provided between each two adjacent heat detectors. One signal input line W1 and one signal output line W2 are provided for each heat detector.

In one embodiment, the wire is made of titanium Tungsten (TiW) and platinum (Pt) and is wound in the shape of a sector ring, each sector ring being arranged in a circular ring outside the central region R1. The heat detector is not limited to metal wires, but may be made of other conductors, such as carbon-based conductors, ITO, etc.

Each pad is made of titanium Tungsten (TiW) and platinum (Pt), and 8 pads are uniformly distributed in the pad region R3 outside the sensing region R2 according to a circumference and are electrically connected with corresponding signal lines, respectively, for outputting sensing signals.

The elastomer 2 is made of Silica gel comprising a mixture of a component A and a component B in a volume ratio of 1:1, wherein the component A is a mixture of polysiloxanes (polyoxosiloxanes), amorphous Silica (Silica, amorphos), platinum-siloxanes (Platinum-Siloxane Complex). The component B is a mixture of polysiloxane (Polyorganosiloxanes) and Amorphous Silica (Silica, amorphos). The elastomer 2 includes, but is not limited to, silica gel, but may also include other materials that are thermally conductive, such as fabrics, polymers, metals, and the like.

Fig. 4 illustrates a state of a pressure sensor when a force is applied according to one embodiment of the present disclosure. When the elastic body 2 receives an external force perpendicular to the elastic body 2, since the young's modulus of the elastic body 2 is relatively low, the elastic body 2 is deformed, resulting in contact between the elastic body 2 and each of the eight heat detectors. Based on the heat transfer principle that heat flux is transferred from the high temperature region to the low temperature region, the temperatures of the heat detectors TD1 to TD8 will decrease due to the contact of the elastic body 2, and thus the resistances of the heat detectors TD1 to TD8 will also decrease, and the currents of the respective heat detectors TD1 to TD8 become large in the case where a constant voltage is applied to the respective heat detectors TD1 to TD 8. The processor detects an external force according to the magnitude of the current in the heat detectors TD1 through TD8, thereby implementing the pressure sensing function of the pressure sensor of the present disclosure.

Fig. 5 illustrates a state of a pressure sensor when a force is applied according to one embodiment of the present disclosure. As shown in fig. 5, the elastic body 2 is inclined with respect to an axis perpendicular to the thermal sensing film 1 in the case where the elastic body 2 receives an external force. The elastic body 2 is deformed, resulting in contact between the elastic body 2 and at least a portion of the heat detectors, such as the heat detectors TD1, TD2, TD 6. Based on the heat transfer principle, the temperature of the heat detectors TD1, TD2, TD6 will decrease due to the contact of the elastomer 2. When a constant voltage is applied to each of the heat detectors, the resistances of the heat detectors TD1, TD2, and TD6 decrease, and the current increases. From the currents in the heat detectors TD1, TD2, TD6 being significantly different from the currents in the other heat detectors, it can be determined that the elastic body 2 presses the heat detectors TD1, TD2, TD6, and thus the direction of the external force. The magnitude of the external force can be determined based on the magnitude of the currents of the heat detectors TD1, TD2, and TD 6.

As shown in fig. 5, the annularly arranged heat detectors are equally divided into 8 parts along 360 degrees for measuring forces in 8 directions. 4 of the 8 heat detectors TD1, TD2, TD3, TD4 are connected to signal lines, respectively, so that sensing signals are transmitted to an external circuit; the other 4 heat detectors TD5, TD6, TD7, TD8 of the 8 heat detectors are not connected to the signal lines, and thus no signal is output. When all 8 heat detectors are connected to the signal line, 8 directional forces can be sensed. In practical applications, the more heat detectors, the finer the division of directions and the more accurate the detection. The number of heat detectors may be designed according to the actual application. The pressure sensor of the present disclosure may be used in wearable electronics and smart electronic skin, among others.

Fig. 6A to 6D show the current flow in each heat detector.

Fig. 6A shows that the current in heat detector TD1 is the largest, the current in heat detector TD3 is the smallest, and the current in heat detector TD4 is comparable to and between the maximum and minimum values of the current in heat detector TD 2.

Fig. 6B shows that the current in heat detector TD2 is the largest, the current in heat detector TD1 is less than the current in heat detector TD2, the current in heat detector TD3 is less than the current in heat detector TD1, the current in heat detector TD4 is the smallest and less than the current of heat detector TD 3.

Fig. 6C shows that the current of the heat detector TD3 is the largest, the current of the heat detector TD2 and the current of the heat detector TD4 are equivalent and smaller than the current of the heat detector TD3, and the current of the heat detector TD1 is the smallest.

Fig. 6D shows that the current of the heat detector TD4 is the largest, the current of the heat detector TD1 and the current of the heat detector TD3 are equivalent and smaller than the current of the heat detector TD4, and the current of the heat detector TD2 is the smallest.

Fig. 7A to 7I illustrate a manufacturing process of a pressure sensor according to an embodiment of the present disclosure. To obtain a skin-safe device, biocompatible materials are used for the manufacture of the pressure sensor. The thermal sensing film is fabricated using a MEMS-based process.

First, as shown in fig. 7A, a 10 μm parylene-C (Galentis) protective layer 3 is deposited on a substrate 8 using a Chemical Vapor Deposition (CVD) process.

As shown in fig. 7B, for patterning the heat detector, a photoresist AZ504 of 1 μm was spin-coated on the protective layer 3 by a SUSS coater (PHT-SC 1), and exposed with an aligner for 5 seconds to 5.5 seconds, and developed with a developer for 60 seconds to 70 seconds. In one embodiment, tiW is used asPt is->Will be about +.>Titanium tungsten->The Pt 4 of (C) is sputtered sequentially on the parylene-C protective layer 3. Thereafter, a lift-off process is performed for patterning of Pt. TiW and Pt have a laminated structure. Since adhesion of Pt on the substrate is not good, a thin TiW layer is formed as an adhesion layer, and then a Pt layer is laminated on the TiW layer, thereby forming each of a pad and a heat detector on the protective layer 3.

As shown in fig. 7C, a protective layer 5 of 10 μm thickness including parylene-C (Galentis) is deposited such that the protective layer 5 covers the heat detector TD and the pads 4.

As shown in fig. 7D, the protective layer 5 made of parylene-C was etched using a Reactive Ion Etching (RIE) system using AZ9260 as a mask layer until the pad 4 made of Pt 4 was exposed. In this step, the protective layer 5 above the individual heat detectors remains.

As shown in fig. 7E, the substrate 8 is peeled off from the protective layers 3 and 5, thereby forming the thermal sensing film 1.

Fig. 8 illustrates a top view of an elastomer according to one embodiment of the present disclosure. The elastomer 2 is manufactured from dragon skin, which exhibits excellent physical properties in terms of flexibility, durability and preparation. Dragon skin is a Silica gel synthesized from component A and component B, wherein component A is a mixture of polysiloxane (polyoxosilanes), amorphous Silica (Silica, amorphos), platinum-Siloxane (Platinum-Siloxane Complex). The component B is a mixture of polysiloxane (Polyorganosiloxanes) and Amorphous Silica (Silica, amorphos). In use, the component A and the component B are mixed according to the volume of 1:1, so that the elastomer can be quickly solidified from a liquid state.

As shown in fig. 7F, the mold 6 is manufactured using a 3D printing method, and the inverted convex shape of the elastic body 2 is manufactured using the mold 6.

As shown in fig. 7G, in order to simplify the subsequent peeling process, a thin parylene-C layer, i.e., a protective layer, having a thickness of 2 μm was deposited on the surface of the 3D printing die 6. Dragon skin was prepared by placing the mixture of component A and component B in a ratio of 1:1 in a vacuum chamber, pumping for 10 minutes to reduce air bubbles, and baking on a hot plate at 70deg.C for one hour.

As shown in fig. 7H, the elastic body 2 is peeled from the die 6.

As shown in fig. 7I, in order to reduce heat loss, the thermal sensing film 1 (i.e., parylene-C film) is attached to the silicone film 7 of the carrier with an adhesive. Because the hollowed-out area on the silicone membrane is opposite to the position of the heat detector, the heat detector is in a suspended state, and heat loss is reduced. Finally, the elastomer 2 and the thermal sensing membrane 1 are encapsulated with an adhesive.

Fig. 9 shows a top view of a thermal sensing film 1 according to one embodiment of the present disclosure. As shown by the broken line in fig. 9, the side length of the thermal sensing film is 10mm. The thermal sensing film 1 is located on the silicone film 7 of the carrier, the thickness of the silicone film being 100 μm and the thickness of the elastomer 2 being 5mm.

Fig. 10 illustrates a perspective view of a pressure sensor according to one embodiment of the present disclosure. As shown in fig. 10, the pressure sensor has a carrier 7, a thermal sensing membrane 1, an elastomer array 2, and a processor. The carrier 7 includes, but is not limited to, flexible materials, such as PET, PC, PVC, ABS, PE, PI, etc., and the carrier 7 may also employ a rigid substrate, such as a wafer, plastic sheet, glass, etc. The thermal sensing membrane 1 is located on a carrier 7. The thermal sensing membrane 1 includes thereon an array of heat detectors having a plurality of heat detectors 1-9, each of the plurality of heat detectors 1-9 having a central region R1, a sensing region R2 annularly surrounding the central region R1. The thermal sensing film 1 also has a pad region R3 surrounding all central regions R1 and all sensing regions R2 of the plurality of heat detectors 1-9. A protective layer of parylene-C is provided in the central region R1. The heat detector array of the plurality of heat detectors 1-9 is arranged in three rows and three columns in the sensing region R2. The elastic body array 2 includes a plurality of elastic bodies 2 arranged in three rows and three columns and in one-to-one correspondence with a plurality of heat detectors 1-9 arranged in three rows and three columns. The plurality of heat detectors 1-9 are connected in parallel. A processor is connected to the thermal sensing membrane and configured to detect the pressure from a temperature change of the thermal sensing membrane.

Each of the elastic bodies 2 in the elastic body array has a planar upper surface S1 distant from the heat sensing film 1 and a curved surface S2 close to the heat sensing film 1 and protruding toward the heat sensing film 1. The orthographic projection of the planar upper surface S1 of each elastic body 2 on the thermal sensing film 1 is circular. The front projection of each elastomer 2 onto the thermal sensing membrane 1 is circular and overlaps with the front projection of the corresponding thermal detector 1-9 onto the thermal sensing membrane 1.

The orthographic projection of each elastomer 2 on the thermal sensing film 1 is located in the respective central region R1 and the respective sensing region R2. The front projection of each elastic body 2 on the heat sensing film 1 overlaps a portion of the front projection of the corresponding heat detector on the heat sensing film 1. In one embodiment, the orthographic projection of each elastic body 2 on the thermal sensing film 1 overlaps the central region R1, overlaps a portion of the sensing region R2, and does not overlap the pad region R3.

A plurality of pads electrically connected to the plurality of heat detectors in one-to-one correspondence are provided in the pad region R3. In one embodiment, 8 pads are located on opposite sides of the plurality of heat detectors 1-9.

The signal input line W1 is routed in a square shape around one of the heat detectors 5 located in the center of the array and the other heat detectors 1-3, 4, 6, 7-9 around the heat detector 5 so as to be electrically connected to the respective heat detectors 1-9. Each heat detector is electrically connected to a corresponding pad via a signal output line W2. A common signal input line W1 is provided for a plurality of heat detectors 1-9, and a signal output line W2 is provided for each heat detector 1-9 individually. External power enters each heat detector via a common signal input line W1, and sensing signals are transmitted to corresponding pads via respective signal output lines W2, so as to be received by an external processor for signal processing.

In response to being not pressurized, the downwardly convex curved surface S2 of each elastic body 2 is in direct contact with the upper surface of the corresponding heat detector, thereby avoiding misalignment of the elastic body 2 with the heat sensing film 1 to affect product performance. In the absence of pressure, the elastic body 2 having the inverted convex surface is not deformed, and the elastic body 2 is not in contact with any one of the heat detectors 1 to 9 on the heat sensing film 1, so that heat transfer is not generated between the elastic body 2 and the heat detectors 1 to 9, and thus the heat detectors 1 to 9 are not subjected to temperature change, and no electric signal is generated.

In the case where the elastic body array is subjected to an external force, a part of the elastic bodies 2 in the elastic body array is subjected to a pressure so that a part of the elastic bodies 2 presses the corresponding heat detector in the heat detector array. Pressure sensing is achieved by monitoring the response of each of the respective heat detectors.

In one embodiment, in the event that the array of elastic bodies is subjected to an external force, for example, when the array of elastic bodies is pressed by braille protrusions having a certain rule, a portion of the elastic bodies 2 in the array of elastic bodies is deformed by the external force, resulting in contact between a portion of the elastic bodies 2 and a portion of the heat detectors (e.g., the heat detectors 2, 5, 8), thereby generating heat transfer between a portion of the elastic bodies 2 and the heat detectors 2, 5, 8, resulting in a decrease in temperature of the heat detectors 2, 5, 8. The resistance of the heat detectors 2, 5, 8 decreases due to the decrease in temperature and the current increases. From the fact that the current of the heat detector 2, 5, 8 is clearly different from the other heat detectors 1, 3-4, 6-7, 9, it can be judged that the elastic body 2 presses the heat detector 2, 5, 8, and thus that the letter is a capital "I". The pressure sensor array in the present application may be integrated with a robotic finger and provide the finger with a pressure mapping function, for example for braille recognition.

FIG. 11 illustrates a plan view of a heat detector according to one embodiment of the present disclosure. As shown in fig. 11, each heat detector has a metal coil structure, which is wound in concentric circles in a clockwise or counterclockwise direction with metal wires, thereby forming the metal coil structure of the heat detector. The structure of each heat detector is not limited thereto, and may be designed according to practical circumstances, for example, each heat detector may have a square planar coil shape or other shapes.

Further, an elastomer array having a plurality of elastomers 2 may be manufactured by 3D printing.

The embodiment of the disclosure also provides a braille recognition device, which comprises the pressure sensor array.

It is to be understood that the above embodiments are merely exemplary embodiments employed to illustrate the principles of the present disclosure, however, the present disclosure is not limited thereto. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the disclosure, and are also considered to be within the scope of the disclosure.

Claims

1. A pressure sensor, comprising:

a carrier;

a thermal sensing membrane on the carrier and comprising at least one heat detector configured to produce a temperature change in response to being subjected to pressure such that a current in the at least one heat detector changes in response to the temperature change;

a processor is connected to the heat detector of the heat sensing diaphragm and configured to detect the pressure from a change in the current.

2. The pressure sensor of claim 1, wherein

The thermal sensing film has a sensing region including a central region, a circular shape surrounding the central region, and a pad region surrounding the sensing region,

a protective layer is formed in the central region,

the at least one heat detector includes a plurality of heat detectors equally spaced uniformly distributed in the sensing region,

a plurality of pads are formed in the pads and are electrically connected to the plurality of heat detectors in a one-to-one correspondence, respectively.

3. The pressure sensor of claim 2, further comprising an elastomer located over the thermal sensing membrane, wherein

The elastic body is deformed by pressure such that the elastic body presses at least a portion of the plurality of heat detectors,

in response to not being subjected to pressure, the elastomer is not in contact with the plurality of heat detectors.

4. The pressure sensor of claim 3, wherein

The front projection of the elastomer onto the thermal sensing membrane overlaps with the front projections of the plurality of thermal detectors onto the thermal sensing membrane.

5. The pressure sensor of claim 3 or 4, wherein

The elastic body has a planar upper surface away from the thermal sensing film and a curved surface protruding toward the thermal sensing film,

the orthographic projection of the planar upper surface of the elastomer on the thermal sensing film is circular.

6. The pressure sensor of claim 5, wherein

The elastomer comprises a silica gel, and the silica gel,

the thickness of the elastomer is 5mm.

7. The pressure sensor of claim 5, wherein

The plurality of heat detectors are equally spaced, circumferentially distributed outside the central region.

8. The pressure sensor of claim 7, wherein

Each of the plurality of heat detectors has a fan-shaped ring-shaped planar coil structure in which conductive wires are wired in an S-shape,

the plurality of heat detectors are equidistant from a center point of the central region,

the plurality of heat detectors are on the same circumference near respective edges of the central region,

the edges of the plurality of heat detectors remote from the central region are also on the same circumference.

9. The pressure sensor of claim 5, wherein

The plurality of heat detectors are arranged in a plurality of rows and columns in a heat detector array.

10. The pressure sensor of claim 9, wherein

Each of the plurality of heat detectors has a concentric circular planar coil structure formed by winding a conductive wire in a clockwise or counterclockwise direction.

11. The pressure sensor of claim 9 or 10, wherein the elastomer comprises an array of elastomers positioned above the thermal sensing membrane and comprising a plurality of elastomers arranged in a plurality of rows and columns, wherein

At least a portion of the plurality of elastic bodies is deformed by pressure such that the portion of the elastic bodies presses a corresponding heat detector of the plurality of heat detectors,

in response to not being subjected to pressure, the plurality of elastomers are not in contact with the plurality of heat detectors.

12. The pressure sensor of claim 11, wherein

The front projection of each elastomer onto the thermal sensing membrane overlaps with the front projection of the corresponding thermal detector onto the thermal sensing membrane.

13. The pressure sensor of claim 11 or 12, wherein

Each elastic body has a planar upper surface away from the thermal sensing film and a curved surface protruding toward the thermal sensing film,

the orthographic projection of the planar upper surface of each elastomer onto the thermal sensing membrane is circular.

14. The pressure sensor of claim 8, wherein

The conductive wire includes one of a metal wire made of titanium tungsten and platinum, a carbon-based conductor, and indium tin oxide.

15. The pressure sensor of claim 1, wherein

The carrier comprises a flexible material.

16. A braille recognition device comprising a pressure sensor according to any of claims 9-13.

17. A method of making a pressure sensor, comprising:

providing a carrier;

forming a thermal sensing film comprising at least one heat detector on the carrier, wherein the heat detector is configured to produce a temperature change in response to being subjected to pressure such that a current in the at least one heat detector changes in response to the temperature change;

a processor is provided that is connected to the heat detector of the heat sensing diaphragm and configured to detect the pressure from a change in the current.

18. The method of claim 16, forming a thermal sensing film comprising at least one thermal detector on the carrier, comprising:

depositing a protective layer on the substrate using a chemical vapor deposition process;

sputtering to form a titanium tungsten layer on the protective layer;

forming a platinum layer on the titanium tungsten layer by sputtering to form a plurality of heat detectors in a sensing region and a plurality of bonding pads in a bonding pad region;

forming a protective layer on the plurality of heat detectors and the plurality of pads such that the protective layer covers the plurality of heat detectors and the plurality of pads;

etching the protective layer in the pad region until the plurality of pads are exposed while retaining the protective layers in the central region and the sensing region;

stripping the substrate from the patterned protective layer, thereby forming the thermal sensing film;

the thermal sensing membrane is attached to the carrier.

19. The method of claim 17, further comprising:

forming an elastomer composed of silica gel using a mold;

encapsulating the elastomer, the thermal sensing film, and the carrier.