CN111855044A - A plantar pressure sensing device and method based on porous PDMS - Google Patents

Abstract

The invention provides a sole pressure sensing device and method based on porous PDMS, wherein the device comprises: the pressure sensitive layer, the signal acquisition chamber and the signal processing device; the pressure sensitive layer is arranged at the top of the signal acquisition chamber, and the signal processing device is connected with the signal acquisition chamber; the pressure sensitive layer comprises a flexible membrane, a flexible porous layer and tempered glass from top to bottom, and the tempered glass supports the flexible membrane and the flexible porous layer; the signal acquisition chamber comprises a box body, an illumination light source, a reflector, a supporting plate and an image acquisition module, and light rays emitted by the illumination light source illuminate the whole flexible porous layer through toughened glass; the image acquisition module acquires the image information of the flexible porous layer in real time through the reflector. The invention adopts an optical method, adopts a simpler hardware structure to collect image information, directly carries out surface measurement on the plantar pressure signal, can realize visualization of plantar pressure response only by simple image change, and greatly reduces the data processing operation amount.

Description

A plantar pressure sensing device and method based on porous PDMS

technical field

The invention relates to gait analysis, more particularly to the field of plantar pressure sensing, and more particularly to a system and method for measuring plantar pressure based on porous PDMS, and this method adopts flexible sensitive elements, which can realize pressure response and The visualization of large-scale pressure distribution can be widely used in the field of medical rehabilitation and human movement science.

Background technique

A pressure sensor is a device or device that can sense pressure and convert the pressure into a usable output signal according to certain rules. Typically, pressure sensors contain pressure sensitive elements and signal processing elements. Wangjoo Lee, Seung-HyeonHong, etc. proposed a piezoresistive insole based on polydimethylsiloxane (PDMS) and carbon nanotubes in 2018; SatuRajala, Timo Salpavaara, Sampo Tuukkanen et al. Thin-film piezoelectric in-shoe sensors of vinylidene fluoride (PVDF), cellulose nanofibers (CNF), and piezoelectric electret films (EMFi). Existing pressure sensors based on piezoelectric, piezoresistive, capacitive, eddy current and other principles mainly convert pressure signals into electrical signals. In some occasions that need to visualize the pressure response, such as gait correction of stroke patients, a conversion system is required to convert the electrical signal into a visual pressure distribution map according to a certain response curve, and compare it with the standard library to achieve correction. Since the electrical signal is measured at a point, such a plantar pressure device has a relatively complex measurement circuit and a signal conversion module, and the calculation amount is relatively large during signal processing.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention adopts an optical method, adopts a simpler hardware structure to collect image information, directly measures the surface of the plantar pressure signal, and then only needs a simple image change to realize the visualization of the plantar pressure response . The invention provides a pressure sensing system and method based on porous PDMS, that is, a transparent material, such as polydimethylsiloxane (PDMS), silica gel, etc., is mixed with a pore-forming agent to form a film with a certain thickness , as a pressure sensitive element, a pressure sensor is made. This technique enables the visualization of pressure response and large-scale pressure distribution through the change of transparency of porous membrane under different pressures.

The present invention provides the following solution: a plantar pressure sensing device based on porous PDMS, comprising:

a pressure sensitive layer, a signal acquisition chamber, and a signal processing device; the pressure sensitive layer is arranged on the top of the signal acquisition chamber, and the signal processing device is connected to the signal acquisition chamber;

The pressure-sensitive layer includes a flexible membrane, a flexible porous layer, and tempered glass from top to bottom, and the tempered glass provides support for the flexible membrane and the flexible porous layer;

The signal acquisition room includes a box, an illumination light source, a reflector, a support plate, and an image acquisition module. The light emitted by the illumination light source illuminates the entire flexible porous layer through the tempered glass; the image acquisition module collects the flexible porous layer in real time through the reflector. image information.

Further, the flexible membrane is made of PDMS material mixed with nano-silver particles, which is black and attached to the flexible porous layer, and transmits the applied pressure to the porous layer under the premise of protecting the porous layer from being polluted.

Further, the flexible porous layer is a pressure-sensitive element, and is made of porous material PDMS, which is white under no pressure, and increases in transparency when the pressure is increased.

Further, the box body provides support for the entire device, and at the same time concentrates the light in the signal collection chamber, and a support plate is provided under the box body for supporting the reflector.

Further, under the action of the upper pressure, the pores of the flexible porous layer are compressed, and the layer thickness is reduced. Under different pressures, its transparency is different, so as to achieve different pressure responses. When the pressure is greater than the threshold, the pores are completely flattened, and the porous layer is completely flat. Transparent, to achieve complete light transmission.

Further, the signal processing device processes the image information of the porous layer collected by the image acquisition module into a grayscale image, and the grayscale image directly shows the pressure distribution in a large area, and at the same time, according to the corresponding relationship between grayscale and pressure, the numerical pressure is given. Distribution.

According to another aspect of the present invention, a plantar pressure sensing method based on porous PDMS is also proposed, comprising the following steps:

Step 1. The user places the foot on the plantar pressure sensing device and stands naturally;

Step 2, the signal acquisition chamber collects the image after the flexible porous layer is stressed and transmits it to the signal processing device;

Step 3, the signal processing device analyzes and displays the user's plantar pressure information, for researchers in the field of sports scientific research and biomechanical engineering to analyze and study the user's plantar pressure information.

The working principle of the pressure sensing device is as follows:

Under the action of no pressure, the pores of the porous layer are not compressed, and the light irradiated from the signal acquisition chamber is diffusely reflected. When there is pressure, the pores are compressed, and the light irradiated from the signal acquisition chamber can partially pass through the porous layer and be absorbed by the black flexible film. At this time, the image collected by the image acquisition module is processed as a grayscale image. Values below 255. When the pressure reaches the upper limit, the pores are completely compressed, the porous layer is completely transparent, and the light irradiated from the signal acquisition chamber completely passes through the porous layer and is completely absorbed by the black film. .

Beneficial effects:

The advantages of the present invention relative to the prior art are:

1. The flexible material is used as the response element, the preparation process is simple, the response range and sensitivity can be flexibly controlled, and the pressure object can be well protected;

2. The image collected by the image acquisition module can directly qualitatively display the pressure distribution, which has a guiding role. At the same time, after a simple conversion, the pressure distribution map can be directly generated, and the pressure value of each part can be quantitatively displayed. The acquisition and processing of the pressure response are all image transformations, and in the analysis of large-area pressure distribution, the amount of computation is much lower than that of other sensing devices.

Description of drawings

FIG. 1 is a schematic diagram of the pressure sensing device based on porous PDMS of the present invention.

Reference numeral description: 1 illumination light source, 2 reflector, 3 support plate, 4 flexible membrane, 5 flexible porous layer, 6 tempered glass, 7 box, 8 image acquisition module, 9 computer.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in Fig. 1, the pressure sensing device based on porous PDMS includes: a pressure sensitive layer, a signal acquisition chamber and a signal processing device. The pressure-sensitive layer includes a flexible film 4, a flexible porous layer 5, and a tempered glass 6. The light irradiated from the signal collection chamber is partially reflected by the flexible porous layer 5, and the rest of the light passing through is closely adhered to the flexible film of the flexible porous layer 5. 4. Absorption, the tempered glass 6 supports the flexible porous layer 5. The signal acquisition room includes an illumination light source 1, a reflector 2, a support plate 3, a box body 7, and an image acquisition module 8. The illumination light source 1 provides sufficient brightness, illuminates the flexible porous layer 5 through the tempered glass 6, and the image acquisition module 8 The image information of the flexible porous layer 5 is collected in real time, the reflector 2 folds the optical path, the support plate 3 supports the reflector 2, and the box 7 supports the entire device while concentrating the light in the signal collection room. The signal processing device includes a computer 9. The computer 9 performs image processing on the image of the flexible porous layer 5 collected in real time by the image acquisition module 8, and provides data such as a numerical pressure distribution map and a pressure center.

The flexible membrane 4 is made of PDMS material mixed with nano-silver particles, which is characterized by black color, good light absorption effect, and can be well attached to the flexible porous layer 5 .

The flexible porous layer 5 is a pressure-sensitive element, and is made of porous material PDMS, which is characterized by white color under no pressure, and increased transparency when the pressure is increased. The response range and sensitivity of the flexible porous layer 5 to pressure can be flexibly controlled by adjusting parameters such as the layer thickness, pore size, pore density, and curing agent ratio of the flexible porous layer 5 .

The working principle of the pressure sensing device is as follows:

Under the action of no pressure, the pores of the porous layer are not compressed, and the light irradiated from the signal acquisition chamber is diffusely reflected. When there is pressure, the pores are compressed, and the light irradiated from the signal acquisition chamber can partially pass through the porous layer and be absorbed by the black flexible film. At this time, the image collected by the image acquisition module is processed as a grayscale image. Values below 255. When the pressure reaches the upper limit, the pores are completely compressed, the porous layer is completely transparent, and the light irradiated from the signal acquisition chamber completely passes through the porous layer and is completely absorbed by the black film. .

According to an embodiment of the present invention, a method for sensing plantar pressure based on porous PDMS is also proposed, comprising the following steps:

Step 1. The user places the foot on the plantar pressure sensing device and stands naturally;

Step 2, the signal acquisition chamber collects the image after the flexible porous layer is stressed and transmits it to the signal processing device;

Step 3, the signal processing device analyzes and displays the user's plantar pressure information, for researchers in the field of sports scientific research and biomechanical engineering to analyze and study the user's plantar pressure information.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the appended claims. All changes within the meaning and range of the equivalents of , are included in the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (7)

1. A plantar pressure sensing device based on porous PDMS is characterized by comprising:

the pressure sensitive layer, the signal acquisition chamber and the signal processing device; the pressure sensitive layer is arranged at the top of the signal acquisition chamber, and the signal processing device is connected with the signal acquisition chamber;

the pressure sensitive layer comprises a flexible membrane, a flexible porous layer and tempered glass from top to bottom, and the tempered glass supports the flexible membrane and the flexible porous layer;

the signal acquisition chamber comprises a box body, an illumination light source, a reflector, a supporting plate and an image acquisition module, and light rays emitted by the illumination light source illuminate the whole flexible porous layer through toughened glass; the image acquisition module acquires the image information of the flexible porous layer in real time through the reflector.

2. The plantar pressure sensing device according to claim 1, wherein the pressure sensing device is composed of a porous PDMS,

the flexible membrane is made of PDMS (polydimethylsiloxane) material mixed with nano silver particles, is black, is attached to the flexible porous layer, and transmits acting pressure to the porous layer on the premise of protecting the porous layer from being polluted.

3. The plantar pressure sensing device according to claim 1, wherein the pressure sensing device is composed of a porous PDMS,

the flexible porous layer is a pressure sensitive element, is made of porous PDMS, is white under the action of no pressure, and has increased transparency when the pressure is enhanced.

4. The plantar pressure sensing device according to claim 1, wherein the pressure sensing device is composed of a porous PDMS,

the box provides the support to whole device, concentrates the light in the signal acquisition room simultaneously, and the box below is provided with the backup pad for support reflector.

5. The plantar pressure sensing device according to claim 1, wherein the pressure sensing device is composed of a porous PDMS,

under the action of upper pressure, the flexible porous layer is compressed, the layer thickness is reduced, under different pressures, the transparency is different, so that different pressure responses are realized, when the pressure is greater than a threshold value, the pores are completely flattened, the porous layer is completely transparent, and the complete light transmission is realized.

6. The plantar pressure sensing device according to claim 1, wherein the pressure sensing device is composed of a porous PDMS,

the signal processing device processes the porous layer image information acquired by the image acquisition module into a gray image, the gray image directly displays the large-area pressure distribution condition, and simultaneously, a numerical pressure distribution diagram is given according to the gray-pressure correspondence.

7. A plantar pressure sensing method based on porous PDMS using the device of claim 1, characterized by comprising the steps of:

step 1, a user places feet on a plantar pressure sensing device and stands naturally;

step 2, the signal acquisition chamber acquires images of the flexible porous layer after being stressed and transmits the images to the signal processing device;

and 3, analyzing and displaying the plantar pressure information of the user by the signal processing device, and analyzing and researching the plantar pressure information of the user by researchers in the fields of sports research and biomechanics engineering.

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