CN108663154B - Flexible wearable air pressure sensor, preparation method and application thereof - Google Patents
Flexible wearable air pressure sensor, preparation method and application thereof Download PDFInfo
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- CN108663154B CN108663154B CN201710206612.XA CN201710206612A CN108663154B CN 108663154 B CN108663154 B CN 108663154B CN 201710206612 A CN201710206612 A CN 201710206612A CN 108663154 B CN108663154 B CN 108663154B
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
- G01L9/06—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of piezo-resistive devices
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Abstract
The invention discloses a flexible wearable air pressure sensor, a preparation method and application thereof. The flexible wearable barometric sensor comprises a flexible top layer having a first surface and a second surface opposite the first surface, the second surface having a microstructure that is capable of a sensitively discernable response to changes in the magnitude of pressure experienced and is electrically connected to a power source; a flexible base layer having a third surface, at least the third surface being electrically conductive and in electrical contact with the microstructure; and a sealed air chamber formed between the flexible top layer and the flexible bottom layer, wherein at least partial chamber walls of the sealed air chamber are formed by at least partial areas of the second surface and at least partial areas of the third surface, and the air pressure in the sealed air chamber reaches a set vacuum degree. The flexible wearable air pressure sensor has the characteristics of flexibility and wearability, the measurable air pressure range is 20KPa to 101KPa, the preparation process is simple, and the cost is low.
Description
Technical Field
The invention relates to a pressure sensor, in particular to a flexible wearable air pressure sensor and a preparation method and application thereof, and belongs to the technical field of microelectronic devices.
Background
With the great development of the intelligent field, the flexible wearable device attracts a great deal of attention of people. Efforts have been made to produce flexible wearable devices that sense various types of external signals, such as flexible pressure sensors, flexible temperature sensors, and flexible stress sensors. Research on such flexible wearable devices focuses on synthesizing or selecting suitable flexible materials, and designing a special device structure or a material microstructure to realize a special function. Meanwhile, on the basis of the existing research, people make a great deal of popularization on the specific application aspect of the existing research results.
But generally speaking, the flexible wearable device still has a great space in the aspect of popularization of practical application. This is primarily limited by the complexity of the process design of the flexible device in a particular application. Therefore, practical application and popularization based on the existing research results are very necessary.
Currently, air pressure sensing devices are widely used in a variety of fields. The traditional air pressure sensing equipment mainly comprises a mercury barometer, a liquid-free barometer and the like, wherein the barometer is manufactured according to the experimental principle of Torricelli (Evangelista Torricelli, 1608-1647), and generally comprises a rigid base made of glass or other solid materials, so that the barometer is fixed in structure and cannot be bent or deformed, and further cannot be applied to special application requirements, such as unsuitability for embedding wearable equipment.
Disclosure of Invention
The invention mainly aims to provide a flexible wearable air pressure sensor, a preparation method and application thereof, so as to overcome the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a flexible wearable air pressure sensor, which comprises:
a flexible top layer having a first surface and a second surface opposite the first surface, the second surface having a microstructure capable of a sensitively discernable response to changes in the magnitude of a pressure experienced, the microstructure being in electrical communication with a power source;
a flexible substrate having a third surface, at least the third surface being electrically conductive and the third surface being in electrical contact with the microstructure;
and a sealed air chamber formed between the flexible top layer and the flexible bottom layer, wherein at least partial chamber walls of the sealed air chamber are formed by at least partial areas of the second surface and at least partial areas of the third surface, and the air pressure in the sealed air chamber reaches a set vacuum degree.
In some preferred embodiments, the microstructures are capable of varying degrees of distinguishable deformation, at least for different pressures experienced.
The embodiment of the invention also provides a preparation method of the flexible wearable air pressure sensor, which comprises the following steps:
preparing a flexible top layer and a flexible bottom layer, respectively, the flexible top layer having a first surface and a second surface opposite to the first surface, the second surface having a microstructure capable of a sensitively distinguishable response to a change in the magnitude of a pressure to be applied, the microstructure being electrically connected to a power source, the flexible bottom layer having a third surface, at least the third surface being electrically conductive and the third surface being electrically in contact with the microstructure;
and arranging the second surface of the flexible top layer opposite to the third surface of the flexible bottom layer under a vacuum condition, and packaging to form a sealed air chamber in at least a partial area of the second surface and at least a partial area of the third surface to obtain the flexible wearable air pressure sensor.
In some preferred embodiments, the preparation method comprises:
respectively preparing a flexible top layer and a flexible bottom layer;
coating an annular sealing material on the surface of the flexible bottom layer, and then covering the flexible top layer on the annular sealing material;
and heating to the melting temperature of the annular sealing material under the vacuum condition, keeping the annular sealing material for a set time, then closing the heat source, keeping the vacuum, naturally cooling, and enabling the flexible top layer and the flexible bottom layer to be bonded under the vacuum condition to form a sealed air chamber on at least partial areas of the second surface and the third surface, so as to obtain the flexible wearable air pressure sensor.
The embodiment of the invention also provides application of the flexible wearable air pressure sensor in the field of air pressure detection.
Compared with the prior art, the invention has the advantages that:
1. the main body material of the flexible wearable air pressure sensor provided by the invention is organic polymer, and generally has the characteristics of flexibility, bending and deformability, so that the prepared air pressure sensor has the characteristics of flexibility and wearability, the requirements of flexible wearable equipment development at present can be well met, and the flexible wearable air pressure sensor can contribute to popularization in the aspect of wearable microelectronic devices;
2. the flexible wearable air pressure sensor provided by the invention can test the air pressure in the range of 20KPa to 101KPa, and the air pressure range can comprise all areas of the earth surface.
3. The flexible wearable air pressure sensor provided by the invention is simple in preparation process and simple in structure, only comprises an upper layer film and a lower layer film, can realize packaging meeting specific conditions only by a method of heating, solidifying and naturally cooling the hot melt adhesive, and is convenient to process and low in cost.
Drawings
FIG. 1 is a schematic structural view of the microstructure of a flexible top layer in an exemplary embodiment of the invention;
FIG. 2 is a schematic view of a flexible bottom layer coated with hot melt adhesive and attached to a flexible top layer in an exemplary embodiment of the invention;
FIG. 3 is a schematic diagram of a flexible wearable barometric pressure sensor fabricated in accordance with an exemplary embodiment of the present invention;
FIG. 4 is a schematic diagram of a testable air pressure range of a flexible wearable air pressure sensor packaged at normal pressure in an exemplary embodiment of the invention;
FIG. 5 is a graph showing the response of a flexible wearable air pressure sensor packaged at atmospheric pressure to different air pressures in an exemplary embodiment of the invention;
fig. 6 is a diagram of a testable air pressure range of a flexible wearable air pressure sensor packaged under a vacuum of 100Pa in an exemplary embodiment of the invention.
Detailed Description
In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide technical solutions of the present invention. The technical solution, its implementation and principles, etc. will be further explained as follows.
One aspect of an embodiment of the present invention provides a flexible wearable barometric pressure sensor, including:
a flexible top layer having a first surface and a second surface opposite the first surface, the second surface having a microstructure capable of a sensitively discernable response to changes in the magnitude of a pressure experienced, the microstructure being in electrical communication with a power source;
a flexible substrate having a third surface, at least the third surface being electrically conductive and the third surface being in electrical contact with the microstructure;
and a sealed air chamber formed between the flexible top layer and the flexible bottom layer, wherein at least partial chamber walls of the sealed air chamber are formed by at least partial areas of the second surface and at least partial areas of the third surface, and the air pressure in the sealed air chamber reaches a set vacuum degree.
In some preferred embodiments, the microstructures are capable of generating different degrees of distinguishable deformation at least for different pressures, and the microstructures are sensitively and discriminately responsive to changes in the magnitude of the externally applied pressure. For example, when the external applied pressure is gradually increased, the tip of the inverted triangle deforms, so that the contact area between the tip and the bottom layer is increased, the contact resistance is reduced, the output current is increased under the same voltage, and finally the response to the change of the external pressure is realized.
Preferably, the microstructure includes a plurality of protrusions formed on the second surface.
Preferably, the shape of the protrusion comprises an inverted pyramid shape.
Preferably, the flexible top layer is electrically conductive throughout, i.e. the flexible top layer should have electrically conductive properties or at least the microstructured surface should have an electrically conductive layer.
In some preferred embodiments, the first surface is provided with a first electrode through which the microstructures are electrically connected to a power source.
Preferably, the first surface is covered with a conductive layer, and the first electrode is disposed on the conductive layer.
In some preferred embodiments, the flexible substrate includes a flexible substrate and a second electrode overlying the flexible substrate, at least a partial region of a surface of the second electrode constituting the third surface.
Preferably, the second electrode includes a conductive layer formed on a surface of the flexible substrate.
Preferably, the conductive layer comprises an Indium Tin Oxide (ITO) layer.
In some preferred embodiments, the flexible top layer comprises any one of a flexible conductive film, a flexible non-conductive film filled with a conductive filler, and a flexible non-conductive substrate having a microstructure surface provided with a conductive coating. I.e. the material of the flexible top layer should comprise a conductive polymer material, a non-conductive polymer material with conductive fillers or a non-conductive polymer material with a conductive coating on the surface of the microstructure.
Preferably, the thickness of the flexible top layer is below 200 μm.
Preferably, the flexible bottom layer should also have electrically conductive properties, or at least any surface (at least the side that is in contact with the flexible top layer) should have an electrically conductive layer, i.e. have good electrical conductivity.
In some preferred embodiments, the flexible substrate includes any one of a flexible conductive film and a flexible non-conductive substrate having a conductive coating layer provided on a surface thereof. Namely, the material of the flexible bottom layer comprises a flexible conductive polymer material or other flexible non-conductive substrate with a conductive coating on the surface.
Preferably, the thickness of the flexible substrate is 500 μm or less.
Preferably, the flexible conductive film should be made of a thin flexible conductive polymer material with good elasticity, such as a PUD/PEDOT: PSS composite film.
Preferably, the material of the flexible non-conductive film comprises a flexible non-conductive polymer.
Preferably, the material of the flexible non-conductive substrate comprises a flexible non-conductive polymer.
Further, the flexible non-conductive polymer should be selected from a polymer material with a relatively thin thickness and good flexibility, such as polyethylene terephthalate (PET), Polydimethylsiloxane (PDMS), etc.
Preferably, the conductive filler includes metal nanoparticles, carbon-based nanomaterials, and the like.
Preferably, the carbon-based nanomaterial includes any one or a combination of two or more of carbon nanotubes, carbon black, and graphene, but is not limited thereto.
Particularly preferably, the carbon nanotubes comprise multi-walled Carbon Nanotubes (CNTs).
Preferably, the air pressure test range of the flexible wearable air pressure sensor is 20-101 KPa, and the air pressure range can include all areas of the earth surface.
Preferably, the operating voltage of the flexible wearable air pressure sensor is less than 5V, and particularly preferably 1V.
In some preferred embodiments, the flexible wearable air pressure sensor further comprises an annular sealing material disposed between the flexible top layer and the flexible bottom layer, and the annular sealing material encloses at least a partial region of the second surface and at least a partial region of the third surface to form the sealed air chamber.
Preferably, the annular sealing material is sealingly connected around the outer peripheral edge of the flexible top layer.
In some preferred embodiments, the vacuum degree of the sealed air chamber is 0 to 101 KPa.
Preferably, the shape of the annular sealing material is the same as that of the flexible top layer, so that the edge of the flexible top layer and the flexible bottom layer can be perfectly adhered conveniently.
Preferably, the annular sealing material comprises an adhesive, particularly preferably a hot melt adhesive, and the higher the purity of the annular sealing material, the better the purity of the annular sealing material, so that the device can be packaged in a mode of melting by heating, cooling and solidifying.
Particularly preferably, the hot melt adhesive comprises a colloid having a melting point below the glass transition temperature of the flexible bottom layer and the flexible top layer.
Furthermore, the hot melt adhesive is preferably selected from colloids with single components and definite melting points, such as high-purity paraffin.
The invention further provides a preparation method of the flexible wearable air pressure sensor, the air pressure sensor is prepared based on the principle of the contact resistance type pressure sensor, a flexible bottom layer and a flexible top layer with a microstructure are selected, and a flexible wearable device sensitive to air pressure change is prepared through a specific packaging technology. The basic structure of the air pressure sensor is similar to that of a contact resistance type pressure sensor, and the air pressure sensor is divided into an upper layer and a lower layer which are respectively called as a flexible top layer and a flexible bottom layer.
Specifically, the method for preparing the flexible wearable air pressure sensor comprises the following steps:
preparing a flexible top layer and a flexible bottom layer, respectively, the flexible top layer having a first surface and a second surface opposite to the first surface, the second surface having a microstructure capable of a sensitively distinguishable response to a change in the magnitude of a pressure to be applied, the microstructure being electrically connected to a power source, the flexible bottom layer having a third surface, at least the third surface being electrically conductive and the third surface being electrically in contact with the microstructure;
and arranging the second surface of the flexible top layer opposite to the third surface of the flexible bottom layer under a vacuum condition, and packaging to form a sealed air chamber in at least a partial area of the second surface and at least a partial area of the third surface to obtain the flexible wearable air pressure sensor.
In some preferred embodiments, the preparation method comprises:
respectively preparing a flexible top layer and a flexible bottom layer;
coating an annular sealing material on the surface of the flexible bottom layer, and then covering the flexible top layer on the annular sealing material;
and heating to the melting temperature of the annular sealing material under the vacuum condition, keeping the annular sealing material for a set time, then closing the heat source, keeping the vacuum, naturally cooling, and enabling the flexible top layer and the flexible bottom layer to be bonded under the vacuum condition to form a sealed air chamber on at least partial areas of the second surface and the third surface, so as to obtain the flexible wearable air pressure sensor.
Different annular sealing materials have different melting temperatures, but when selecting a sealant, it is not easy to select a material with a melting temperature of more than 80 ℃, i.e. preferably, the melting temperature is less than 80 ℃.
Preferably, the set time is within 2 min.
Preferably, the air pressure test range of the flexible wearable air pressure sensor is 20-101 KPa, and the air pressure range can include all areas of the earth surface.
In some preferred embodiments, the vacuum degree of the air pressure cavity is 0 to 101 KPa.
Preferably, the operating voltage of the flexible wearable air pressure sensor is less than 5V, and particularly preferably 1V.
Preferably, the sensitivity of the flexible wearable air pressure sensor is 0.087 KPa-1-5.25 KPa-1.
In some preferred embodiments, the microstructure is capable of generating different degrees of distinguishable deformation at least for different pressures, and the microstructure can sensitively (sensitivity is 0.087KPa-1 to 5.25KPa-1) distinguish response to the change of the external applied pressure. For example, when the external applied pressure is gradually increased, the tip of the inverted triangle deforms, so that the contact area between the tip and the bottom layer is increased, the contact resistance is reduced, the output current is increased under the same voltage, and finally the response to the change of the external pressure is realized.
Preferably, the microstructure includes a plurality of protrusions formed on the second surface.
Preferably, the shape of the protrusion comprises an inverted pyramid shape.
Preferably, the flexible top layer is electrically conductive throughout, i.e. the flexible top layer should have electrically conductive properties or at least the microstructured surface should have an electrically conductive layer.
In some preferred embodiments, the first surface is provided with a first electrode through which the microstructures are electrically connected to a power source.
Preferably, the first surface is covered with a conductive layer, and the first electrode is disposed on the conductive layer.
In some preferred embodiments, the flexible substrate includes a flexible substrate and a second electrode overlying the flexible substrate, at least a partial region of a surface of the second electrode constituting the third surface.
Preferably, the second electrode includes a conductive layer formed on a surface of the flexible substrate.
Preferably, the conductive layer comprises an Indium Tin Oxide (ITO) layer.
In some preferred embodiments, the flexible top layer comprises any one of a flexible conductive film, a flexible non-conductive film filled with a conductive filler, and a flexible non-conductive substrate having a microstructure surface provided with a conductive coating. I.e. the material of the flexible top layer should comprise a conductive polymer material, a non-conductive polymer material with conductive fillers or a non-conductive polymer material with a conductive coating on the surface of the microstructure.
Preferably, the thickness of the flexible top layer is below 200 μm.
Preferably, the flexible bottom layer should also have electrically conductive properties, or at least any surface (at least the side that is in contact with the flexible top layer) should have an electrically conductive layer, i.e. have good electrical conductivity.
In some preferred embodiments, the flexible substrate includes any one of a flexible conductive film and a flexible non-conductive substrate having a conductive coating layer provided on a surface thereof. Namely, the material of the flexible bottom layer comprises a flexible conductive polymer material or other flexible non-conductive substrate with a conductive coating on the surface.
Preferably, the thickness of the flexible substrate is 500 μm or less.
Preferably, the flexible conductive film should be made of a thin flexible conductive polymer material with good elasticity, such as a PUD/PEDOT: PSS composite film.
Preferably, the material of the flexible non-conductive film comprises a flexible non-conductive polymer.
Preferably, the material of the flexible non-conductive substrate comprises a flexible non-conductive polymer.
Further, the flexible non-conductive polymer should be selected from a polymer material with a relatively thin thickness and good flexibility, such as polyethylene terephthalate (PET), Polydimethylsiloxane (PDMS), etc.
Preferably, the conductive filler includes metal nanoparticles, carbon-based nanomaterials, and the like.
Preferably, the carbon-based nanomaterial includes any one or a combination of two or more of carbon nanotubes, carbon black, and graphene, but is not limited thereto.
Particularly preferably, the carbon nanotubes comprise multi-walled Carbon Nanotubes (CNTs).
Preferably, the material of the annular sealing material comprises an adhesive, and particularly preferably a hot melt adhesive, and the higher the purity of the annular sealing material is, the better the purity is, so that the device can be packaged in a mode of melting by heating, cooling and solidifying.
Preferably, the packaging method comprises a hot melt adhesive cooling and adhering method, and other flexible adhesive adhering methods can be included.
Preferably, the shape and size of the hot melt adhesive coated on the flexible bottom layer are equal to those of the flexible top layer as much as possible, the rubber rings are continuous, and the amount of the rubber rings coated is as small as possible, so that the area of direct contact between the flexible top layer and the flexible bottom layer is ensured to be as large as possible after the flexible top layer and the flexible bottom layer are adhered, and the edge of the flexible top layer and the flexible bottom layer are perfectly adhered.
Particularly preferably, the hot melt adhesive should be selected from a colloid having a melting point below the glass transition temperature of the flexible bottom layer and the flexible top layer.
Furthermore, the hot melt adhesive is preferably selected from colloids with single components and definite melting points, such as high-purity paraffin.
Furthermore, when the hot melt adhesive is heated, after the heating temperature reaches the temperature of the hot melt adhesive, the heat source is easily closed as soon as possible, the colloid is prevented from being in a melting state for a long time and being excessively diffused between the flexible bottom layer and the flexible top layer, and even all gaps between the two layers are filled.
In some preferred embodiments, the preparation method comprises: adding multi-wall carbon nano tubes into Polydimethylsiloxane (PDMS), uniformly dispersing to form a mixed material, and spin-coating the mixed material on a silicon chip with a microstructure by using a spin-coating method to obtain a flexible top layer with the microstructure. This flexible top layer satisfies the requirement of flexibility and electric conductivity simultaneously, after the external world applys certain pressure, the microstructure takes place deformation, top layer and bottom effective area of contact increase, and contact resistance reduces, and under the rated voltage, device output current increases, cancels pressure, because PDMS elasticity makes the microstructure deformation resume, effective area of contact reduces, and contact resistance increases, under the rated voltage, device output current increases to realize that device output current applys the response of pressure to the external world.
Preferably, the mass ratio of the multi-walled carbon nanotubes to the polydimethylsiloxane is 1: 100-5: 100.
in some specific embodiments, the preparation method may include the following steps:
selecting a mixed material with 2% CNTs by mass uniformly dispersed in PDMS, and spin-coating the mixed material on a silicon chip with a microstructure by a spin-coating method, thereby preparing a flexible top layer with the microstructure. And then, taking the PET film which is spin-coated with a thin conductive coating ITO as a flexible bottom layer, and coating a circle of hot melt adhesive (high-purity paraffin is selected) on the surface of the conductive coating ITO, wherein the shape of the circle is close to the size and the shape of the flexible top layer, so that the edge of the top layer is conveniently and perfectly adhered to the bottom layer. And then, heating the device to be packaged to the melting temperature of the hot melt adhesive under different vacuum conditions and keeping the temperature for a certain time, then closing a heat source, keeping the vacuum, and naturally cooling to finish the adhesion between the flexible top layer and the flexible bottom layer under different vacuum conditions, thereby obtaining the devices with different vacuum degrees between the flexible top layer and the flexible bottom layer. Finally, the air pressure sensor capable of testing different air pressure change intervals is obtained.
The embodiment of the invention also provides application of the flexible wearable air pressure sensor in the field of air pressure detection.
For example, the embodiment of the present invention further provides a flexible wearable device, which includes the foregoing flexible wearable air pressure sensor.
By the technical scheme, the main body material of the flexible wearable air pressure sensor provided by the invention is made of organic polymers, and generally has the characteristics of flexibility, bending and deformability, so that the manufactured air pressure sensor has the characteristics of flexibility and wearability, the measurable air pressure range of the air pressure sensor is 20KPa to 101KPa, and the air pressure range can include all regions on the earth surface. The invention has simple preparation process and simple structure, only comprises an upper layer film and a lower layer film, can realize the packaging meeting specific conditions only by a method of heating, solidifying and naturally cooling the hot melt adhesive, and has convenient processing and low cost.
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and some exemplary embodiments.
Example 1
Mixing a PDMS base solution and CNTs (multi-walled carbon nanotubes) according to a mass ratio of 100:2, then preparing a mixed solution with chloroform according to a volume ratio of 1:4, then stirring for 12 hours to ensure that the CNTs are uniformly mixed in the PDMS, heating to ensure that the chloroform is completely volatilized, and then spin-coating the residual mixture on a silicon wafer with a microstructure to prepare a flexible top layer with a microstructure, as shown in FIG. 1. Then, a thin layer of ITO-spun PET film was selected as the flexible substrate, and a high-purity paraffin of appropriate morphology was coated on the flexible substrate, as shown in fig. 2. Then, under normal pressure (101KPa), melting the high-purity paraffin by heating, then closing the heat source, keeping vacuum, naturally cooling, naturally sticking the flexible top layer and the flexible bottom layer, and finally obtaining the flexible wearable air pressure sensor capable of testing different air pressure intervals as shown in figure 3.
When the flexible wearable air pressure sensor prepared by the embodiment is subjected to an electrical performance test, a device packaged under normal pressure (101KPa) can accurately test the air pressure range as shown in fig. 4, and the response to different air pressures is shown in fig. 5.
Example 2
Mixing a PDMS base solution and CNTs (multi-walled carbon nanotubes) according to a mass ratio of 100:2, then preparing a mixed solution with chloroform according to a volume ratio of 1:4, then stirring for 12 hours to ensure that the CNTs are uniformly mixed in the PDMS, heating to ensure that the chloroform is completely volatilized, and then spin-coating the residual mixture on a silicon wafer with a microstructure to prepare a flexible top layer with a microstructure, as shown in FIG. 1. Then, a thin layer of ITO-spun PET film was selected as the flexible substrate, and a high-purity paraffin of appropriate morphology was coated on the flexible substrate, as shown in fig. 2. And then melting the high-purity paraffin by heating under the condition that the vacuum degree is 100Pa, then closing a heat source, keeping vacuum, naturally cooling, naturally sticking the flexible top layer and the flexible bottom layer, and finally obtaining the flexible wearable air pressure sensor capable of testing different air pressure intervals as shown in figure 3.
The flexible wearable air pressure sensor prepared by the embodiment is subjected to an electrical performance test, and the air pressure range of the device packaged under the condition that the vacuum degree is 100Pa can be accurately tested is shown in fig. 6.
Example 3
Mixing PDMS base solution and CB (carbon black) according to a mass ratio of 100:5, preparing a mixed solution with trichloromethane according to a volume ratio of 1:4, stirring for 12 hours to ensure that the CB is uniformly mixed in the PDMS, heating to ensure that the trichloromethane is completely volatilized, and then spin-coating the residual mixture on a silicon wafer with a microstructure to prepare a flexible top layer with a microstructure, wherein the flexible top layer is shown in figure 1. Then, a thin layer of ITO-spun PET film was selected as the flexible substrate, and a high-purity paraffin of appropriate morphology was coated on the flexible substrate, as shown in fig. 2. Then, under the normal pressure condition (101KPa), melting the high-purity paraffin by heating, then closing the heat source, naturally cooling, naturally sticking the flexible top layer and the flexible bottom layer, and finally obtaining the flexible wearable air pressure sensor for testing different air pressure intervals in the same way as shown in figure 3.
Example 4
Firstly, uniformly mixing PDMS base liquid and a cross-linking agent in a ratio of 10:1, removing air bubbles in the solution by adopting a vacuumizing mode, then spin-coating the prepared PDMS mixed liquid on a silicon wafer with a microstructure to prepare a flexible film with the microstructure, and then coating a layer of PEDOT on one side of the film with the microstructure by adopting an inclined drip-drop method: PSS solution, after which the prepared sample was placed in a vacuum oven at 80 ℃ for half an hour, allowing PEDOT: the PSS solution cures to a film and perfectly covers the microstructure surface. Then, a PET film with a 3 nanometer Cr film and a 5 nanometer Au film deposited successively by a high-temperature deposition method is selected as a flexible bottom layer, and high-purity paraffin with a proper shape is coated on the flexible bottom layer, as shown in figure 2. Then, under the normal pressure condition (101KPa), melting the high-purity paraffin by heating, then closing the heat source, naturally cooling, naturally sticking the flexible top layer and the flexible bottom layer, and finally obtaining the flexible wearable air pressure sensor for testing different air pressure intervals in the same way as shown in figure 3.
Through the embodiments 1-4, it can be found that the flexible wearable air pressure sensor prepared by the technical scheme of the invention can stably and accurately test the air pressure in different areas, is sensitive to air pressure change, and can finally realize the modulation of the testable range of the device by modulating the vacuum degree during packaging.
In addition, the inventor also refers to the schemes of the embodiments 1 to 4, tests are performed on flexible top layers made of different materials, flexible bottom layers made of different materials, packaging processes under different conditions, and the like, and a flexible wearable air pressure sensor capable of testing different air pressure change intervals is manufactured.
It should be noted that the drawings of the present embodiment are in a very simplified form and all use non-precise ratios, which are only used for convenience and clarity to aid in the description of the embodiments of the present invention.
Therefore, the scope of the present invention should not be limited to the disclosure of the embodiments, but includes various alternatives and modifications without departing from the scope of the present invention, which is defined by the claims of the present patent application.
Claims (48)
1. A flexible wearable barometric sensor, comprising:
a flexible top layer having a first surface and a second surface opposite to the first surface, the second surface having a microstructure capable of generating different degrees of distinguishable deformation in response to different pressures, the microstructure including a plurality of protrusions formed on the second surface, the microstructure being electrically connected to a power source, the flexible top layer being selected from any one of a flexible conductive film, a flexible non-conductive film filled with a conductive filler, and a flexible non-conductive substrate having a conductive layer on a surface of the microstructure;
a flexible substrate having a third surface, at least the third surface being conductive and the third surface being in electrical contact with the microstructure, the flexible substrate being selected from any one of a flexible conductive film and a flexible non-conductive substrate having a conductive layer provided on a surface thereof;
the sealed air chamber is formed between the flexible top layer and the flexible bottom layer, at least a partial chamber wall of the sealed air chamber is formed by at least a partial region of the second surface and at least a partial region of the third surface, the air pressure in the sealed air chamber reaches a set vacuum degree, the vacuum degree of the sealed air chamber is 0-101 KPa, the air pressure test range of the flexible wearable air pressure sensor is 20-101 KPa, and the sensitivity is 0.087KPa-1～5.25KPa-1；
And the annular sealing material is arranged between the flexible top layer and the flexible bottom layer, and the annular sealing material and at least partial areas of the second surface and the third surface enclose to form the sealing air chamber.
2. The flexible wearable air pressure sensor of claim 1, wherein: the shape of the protruding part is an inverted pyramid.
3. The flexible wearable air pressure sensor of claim 1, wherein: the microstructured surface has a conductive layer.
4. The flexible wearable air pressure sensor of claim 1, wherein: the first surface is provided with a first electrode, and the microstructure is electrically connected with a power supply through the first electrode.
5. The flexible wearable air pressure sensor of claim 4, wherein: the first surface is covered with a conductive layer, and the first electrode is arranged on the conductive layer.
6. The flexible wearable air pressure sensor of claim 1, wherein: the flexible top layer is electrically conductive throughout.
7. The flexible wearable air pressure sensor of claim 1, wherein: the flexible bottom layer comprises a flexible substrate and a second electrode covered on the flexible substrate, and at least partial area of the surface of the second electrode forms the third surface.
8. The flexible wearable air pressure sensor of claim 7, wherein: the second electrode comprises a conductive layer formed on the surface of the flexible substrate.
9. The flexible wearable air pressure sensor of claim 8, wherein: the conducting layer is an ITO layer.
10. The flexible wearable air pressure sensor of claim 1, wherein: the annular sealing material is sealingly connected around an outer peripheral edge of the flexible top layer.
11. The flexible wearable air pressure sensor of claim 1, wherein: the thickness of the flexible top layer is below 200 μm.
12. The flexible wearable air pressure sensor of claim 1, wherein: the conductive filler is selected from metal nanoparticles and/or carbon-based nanomaterials.
13. The flexible wearable air pressure sensor of claim 12, wherein: the carbon-based nano material is selected from any one or a combination of more than two of carbon nano tubes, carbon black and graphene.
14. The flexible wearable air pressure sensor of claim 13, wherein: the carbon nanotubes are selected from multi-walled carbon nanotubes.
15. The flexible wearable air pressure sensor of claim 1, wherein: the thickness of the flexible bottom layer is below 500 mu m.
16. The flexible wearable air pressure sensor of claim 1, wherein: the flexible conductive film is made of flexible conductive polymer.
17. The flexible wearable air pressure sensor of claim 1, wherein: the flexible non-conductive film is made of flexible non-conductive polymer.
18. The flexible wearable air pressure sensor of claim 1, wherein: the flexible non-conductive substrate is made of a flexible non-conductive polymer.
19. The flexible wearable air pressure sensor of claim 18, wherein: the flexible non-conductive polymer is selected from polyethylene terephthalate and/or polydimethylsiloxane.
20. The flexible wearable air pressure sensor of claim 1, wherein: the working voltage of the flexible wearable air pressure sensor is below 5V.
21. The flexible wearable air pressure sensor of claim 1, wherein: the shape of the annular sealing material is the same as the shape of the flexible top layer.
22. The flexible wearable air pressure sensor of claim 21, wherein: the annular sealing material is selected from adhesives.
23. The flexible wearable air pressure sensor of claim 22, wherein: the annular sealing material is hot melt adhesive.
24. The flexible wearable air pressure sensor of claim 23, wherein: the hot melt adhesive is a colloid with the melting point lower than the glass transition temperature of the flexible bottom layer and the flexible top layer.
25. The flexible wearable air pressure sensor of claim 24, wherein: the hot melt adhesive is paraffin.
26. A method of making a flexible wearable barometric sensor according to any of claims 1 to 25, comprising:
respectively preparing a flexible top layer and a flexible bottom layer, wherein the flexible top layer is selected from any one of a flexible conductive film, a flexible non-conductive film filled with conductive fillers and a flexible non-conductive substrate with a conductive layer arranged on the surface of a microstructure, and the flexible bottom layer is selected from any one of the flexible conductive film and the flexible non-conductive substrate with the conductive layer arranged on the surface;
the flexible top layer has a first surface and a second surface opposite the first surface, the second surface having a microstructure capable of undergoing different degrees of distinguishable deformation in response to different pressures experienced by the flexible top layer, the microstructure including a plurality of protrusions formed on the second surface to electrically connect the microstructure to a power source, the flexible bottom layer having a third surface, at least the third surface being electrically conductive and electrically contacting the third surface with the microstructure;
arranging the second surface of the flexible top layer opposite to the third surface of the flexible bottom layer under vacuum condition, coating a ring-shaped sealing material on the surface of the flexible bottom layer, and then covering the flexible top layer on the ring-shaped sealing material;
and heating to the melting temperature of the annular sealing material under the vacuum condition, keeping the annular sealing material for a set time, then closing the heat source, keeping the vacuum, naturally cooling, and enabling the flexible top layer and the flexible bottom layer to be bonded under the vacuum condition to form a sealed air chamber on at least partial areas of the second surface and the third surface, so as to obtain the flexible wearable air pressure sensor.
27. The method of claim 26, wherein: the melting temperature is less than 80 ℃.
28. The method of claim 26, wherein: the set time is within 2 min.
29. The method of claim 26, wherein: the working voltage of the flexible wearable air pressure sensor is below 5V.
30. The method of claim 26, wherein: the shape of the protruding part is an inverted pyramid.
31. The method of claim 26, wherein: the microstructured surface has a conductive layer.
32. The method of claim 26, wherein: the flexible bottom layer comprises a flexible substrate and a second electrode covered on the flexible substrate, and at least partial area of the surface of the second electrode forms the third surface.
33. The method of claim 32, wherein: the second electrode is selected from a conductive layer formed on the surface of the flexible substrate.
34. The method of claim 33, wherein: the conductive layer is selected from an ITO layer.
35. The method of claim 26, wherein: the flexible conductive film is made of flexible conductive polymer.
36. The method of claim 26, wherein: the flexible non-conductive film is made of flexible non-conductive polymer.
37. The method of claim 26, wherein: the flexible non-conductive substrate is made of a flexible non-conductive polymer.
38. The method of claim 36, wherein: the flexible non-conductive polymer is selected from polyethylene terephthalate and/or polydimethylsiloxane.
39. The method of claim 26, wherein: the conductive filler is selected from carbon nanotubes.
40. The method of claim 39, wherein: the carbon nanotubes are selected from multi-walled carbon nanotubes.
41. The method of claim 40, comprising: adding multi-walled carbon nanotubes into polydimethylsiloxane, uniformly dispersing to form a mixed material, and spin-coating the mixed material on a silicon chip with a microstructure by adopting a spin-coating method to obtain a flexible top layer with a microstructure.
42. The method of claim 41, wherein: the mass ratio of the multi-walled carbon nanotube to the polydimethylsiloxane is 1: 100-5: 100.
43. the method of claim 26, wherein: the shape of the annular sealing material is the same as the shape of the flexible top layer.
44. The method of claim 43, wherein: the annular sealing material is selected from adhesives.
45. The method of claim 44, wherein: the annular sealing material is hot melt adhesive.
46. The method of claim 45, wherein: the hot melt adhesive is selected from colloids having a melting point below the glass transition temperature of the flexible bottom layer and the flexible top layer.
47. The method of claim 46, wherein: the hot melt adhesive is paraffin.
48. A flexible wearable device comprising the flexible wearable barometric sensor of any one of claims 1-25.
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| CN112161738B (en) * | 2020-09-17 | 2022-04-08 | 五邑大学 | Air pressure sensor and manufacturing method thereof |
| CN113008416B (en) * | 2021-01-28 | 2022-09-20 | 广东粤港澳大湾区黄埔材料研究院 | Packaging mechanism and packaging method for microstructure type flexible pressure sensor |
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| CN104803339A (en) * | 2015-04-21 | 2015-07-29 | 电子科技大学 | Flexible micro pressure sensor and preparation method thereof |
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