CN111248878A - Flexible pressure sensor and pulse condition measuring device - Google Patents

Abstract

The invention discloses a flexible pressure sensor, comprising: a flexible substrate; a plurality of first flexible electrodes disposed on the flexible substrate; the flexible dielectric layer is arranged on the plurality of first flexible electrodes, and the dielectric constant of the flexible dielectric layer is changed under the action of different pressures; and the second flexible electrode is arranged on the flexible dielectric layer. The invention also provides a pulse condition measuring device. The invention solves the problem of lower sensitivity of the existing pressure sensor.

Description

Flexible pressure sensor and pulse condition measuring device

technical field

The invention relates to the technical field of pressure sensors, in particular to a flexible pressure sensor and a pulse condition measuring device.

Background technique

The human pulse can transmit the physiological and pathological information of the cardiovascular system. Because "the pulse is subtle, its body is difficult to distinguish, and it is easy to understand in the heart, it is difficult to understand under the finger", to be able to feel the obvious changes under the hands not only requires experience but also personal understanding, so it is difficult to learn and inherit. The use of modern computer-aided analysis can partially overcome the above shortcomings, thereby improving the application of TCM pulse diagnosis. Due to the limitation of the development of sensor technology, the pulse waveform analysis obtained by single-part and single-point pulse sensor is mainly used at present. However, the single-point pulse sensor has poor repeatability, a small gap in the collection position will cause a large error in the signal, and the amount of information is not rich enough, it is difficult to simulate the process of pulse cutting in traditional Chinese medicine, and the phenomenon of "the pulse is not symptomatic and the pulse is not dependent" occurs.

The process of TCM pulse diagnosis is that TCM uses three fingers to lift, press, and search on the cun, guan, and chi three parts, and then diagnose the disease based on experience and the feeling under the fingers. The structure of the finger is like multiple flexible, tiny, touch sensor units that can feel multi-dimensional force. The information obtained through many sensing units, through a certain biological process, forms a feeling, and finally gives a final conclusion based on experience.

In the aspect of objectification and quantification of traditional Chinese medicine, predecessors have done a lot of work and invented various forms of pulse meters. However, most of these pulse meters are based on unit-type pressure sensors, which are mostly rigid and clumsy, which are easy to cause discomfort to the subjects, and the amount of information is small.

At present, flexible pressure sensors are mainly divided into four categories: piezoresistive, piezoelectric, transistor and capacitive. Among them, the resistance type has low precision, and the relaxation time is long, which is easily affected by temperature and has large drift; the piezoelectric type is only used for dynamic monitoring, and requires a special type of amplifier, which is not easy to integrate; the transistor type has a complex structure; The formula is mainly prepared by semiconductor technology, which has high cost, low sensitivity and easy interference.

In order to solve the problem of pulse collection in traditional Chinese medicine, the developed pulse sensor must be flexible contact type and meet the following characteristics: dot matrix, high precision, high sensitivity, large detection range, static pressure and dynamic pressure, can be in floating Accurately detect the pulse beat under external pressure such as , medium and heavy. However, today's flexible pressure sensors with high sensitivity only work in a very limited low pressure range, while their sensitivity is low with a large detection range.

SUMMARY OF THE INVENTION

In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme:

A flexible pressure sensor comprising:

flexible substrate;

a plurality of first flexible electrodes disposed on the flexible substrate;

a flexible dielectric layer, disposed on the plurality of first flexible electrodes, and the dielectric constant of the flexible dielectric layer changes under the action of different pressures;

The second flexible electrode is disposed on the flexible dielectric layer.

Preferably, the flexible pressure sensor further comprises:

The analog-to-digital conversion device is arranged on the flexible substrate, and each first flexible electrode is independently and electrically connected to the analog-to-digital conversion device.

Preferably, the flexible dielectric layer comprises a composite of at least one of graphene, carbon nanotubes, silver nanowires, copper nanowires, nano barium carbonate particles, nano titanium dioxide and a high molecular polymer elastomer.

Preferably, the high molecular polymer elastomer includes one of styrene block copolymer, thermoplastic polyurethane, polyolefin-based elastomer, polystyrene-based elastomer, polyamide-based elastomer, and silicone rubber.

Preferably, the first flexible electrode and/or the second flexible electrode are woven from conductive fibers.

Preferably, the thickness of the flexible dielectric layer is 50 μm˜200 μm.

Preferably, the area of the first flexible electrodes is 1 mm ² to 4 mm ² , and/or the distance between two adjacent first flexible electrodes is 0.1 mm to 0.2 mm.

Preferably, the area occupied by the plurality of first flexible electrodes is 0.6 cm ² to 1 cm ² .

Preferably, the first flexible electrode is square.

The present invention also provides a pulse condition measuring device, comprising the above-mentioned flexible pressure sensor and a processor, wherein the processor is configured to receive a digital signal sent by the analog-to-digital conversion device.

Compared with the prior art, the dielectric constant of the dielectric layer of the flexible pressure sensor of the present invention greatly changes with the change of different external pressures, so that the capacitance value of the flexible pressure sensor increases with the pressure change rate. Thus, the sensitivity and pressure detection range of the flexible pressure sensor are improved.

Description of drawings

1 is a schematic structural diagram of a flexible pressure sensor of the present invention;

2 is a cross-sectional view of the flexible pressure sensor of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described with reference to the drawings are merely exemplary and the invention is not limited to these embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and the related structures and/or processing steps are omitted. Other details not relevant to the invention.

Example 1

As shown in FIGS. 1 and 2 , the flexible pressure sensor provided in this embodiment includes a flexible substrate 1 , a plurality of first flexible electrodes 2 , a flexible dielectric layer 3 , a second flexible electrode 4 and an analog-to-digital conversion device 5 . The plurality of first flexible electrodes 2 are arranged on the flexible substrate 1, the flexible dielectric layer 3 is arranged on the plurality of first flexible electrodes 2, and the second flexible electrodes 4 are arranged on the on the flexible dielectric layer 3 . The analog-to-digital conversion device 5 is also disposed on the flexible substrate, and is electrically connected to each of the first flexible electrodes 2 and the second flexible electrodes 4 .

Wherein, the flexible dielectric layer 3 is a composite (for example: One of styrene block copolymer, thermoplastic polyurethane, polyolefin-based elastomer, polystyrene-based elastomer, polyamide-based elastomer, and silicone rubber), with a thickness of 50 μm to 200 μm. The dielectric constant of the flexible dielectric layer 3 will be greatly changed under the action of different pressures. Thus, the sensitivity of the flexible pressure sensor is increased, and the detection range of the pressure sensor is improved.

As a further improvement, the first flexible electrode 2 and/or the second flexible electrode 4 are square and are woven from conductive fibers. Wherein, the area of the first flexible electrode 2 is 1 mm ² to 4 mm ² . The distance between two adjacent first flexible electrodes 2 is 0.1 mm˜0.2 mm. The area occupied by the plurality of first flexible electrodes 2 is 0.6 cm ² to 1 cm ² .

Example 2

Based on Embodiment 1, in this embodiment, the flexible pressure sensor may include a plurality of first flexible electrodes 2 arranged in a matrix. The number of horizontal rows of the first flexible electrodes 2 ranges from 4 to 5, and the number of vertical rows ranges from 5 to 6. The flexible pressure sensor of this embodiment has enough sensing units, which is beneficial to cover the radial artery.

Example 3

Based on Embodiment 1, in this embodiment, the flexible dielectric layer 3 is preferably a composite of graphene and silicone rubber, and the volume fraction of graphene in the composite is 1%. The dielectric constant of the flexible dielectric layer 3 will be greatly changed under the action of different pressures, thereby increasing the sensitivity of the flexible pressure sensor.

Example 4

Based on Embodiment 1, in this embodiment, the flexible dielectric layer 3 is preferably a composite of copper nanowires and polyamide-based elastomer, and the volume fraction of copper nanowires in the composite is 2.5%. The Young's modulus of the flexible dielectric layer 3 is relatively high, so the detectable pressure range is relatively large, which further improves the detection range of the flexible pressure sensor.

Example 5

Based on Embodiment 1, in this embodiment, the flexible dielectric layer 3 is preferably a composite of silver nanowires and a polyamide-based elastomer, and the volume fraction of silver nanowires in the composite is 2%. The Young's modulus of the flexible dielectric layer 3 is relatively high, so the detectable pressure range is relatively large, and the bending performance of the flexible pressure sensor is improved.

Example 6

Based on Example 1, in this example, the flexible dielectric layer 3 is preferably a composite of carbon nanotubes and thermoplastic polyurethane, and the volume fraction of carbon nanotubes in the composite is 1.5%. A small amount of doping not only makes the composite The dielectric constant of the material is greatly increased while retaining the flexibility of the original polymer.

In another aspect of the present invention, a pulse condition measuring device is provided. The device includes the flexible pressure sensor of any of the above embodiments and a processor. The processor is used to receive the digital signal sent by the analog-to-digital conversion device 5 and convert it into a three-dimensional dynamic image, which can display more accurate, vivid, vivid and intuitive pulse characteristics.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. a flexible pressure sensor, is characterized in that, comprises: flexible substrate (1); a plurality of first flexible electrodes (2) arranged on the flexible substrate (1); a flexible dielectric layer (3), disposed on the plurality of first flexible electrodes (2), the dielectric constant of the flexible dielectric layer (3) is changed under the action of different pressures; The second flexible electrode (4) is arranged on the flexible dielectric layer (3). 2. The flexible pressure sensor according to claim 1, further comprising: An analog-to-digital conversion device (5) is arranged on the flexible substrate, and each first flexible electrode (2) is independently electrically connected to the analog-to-digital conversion device (5). 3. The flexible pressure sensor according to claim 1 or 2, wherein the flexible dielectric layer (3) comprises graphene, carbon nanotubes, silver nanowires, copper nanowires, nano-barium carbonate particles, nano- A composite of at least one of titanium dioxide and a high molecular polymer elastomer. 4. The flexible pressure sensor according to claim 3, wherein the high molecular polymer elastomer comprises styrene block copolymer, thermoplastic polyurethane, polyolefin-based elastomer, polystyrene-based elastomer, polystyrene A kind of amide elastomer and silicone rubber. 5. The flexible pressure sensor according to claim 1, wherein the first flexible electrode (2) and/or the second flexible electrode (4) are woven from conductive fibers. 6 . The flexible pressure sensor according to claim 1 , wherein the thickness of the flexible dielectric layer ( 3 ) is 50 μm˜200 μm. 7 . 7. The flexible pressure sensor according to claim 1, characterized in that, the area of the first flexible electrode (2) is 1 mm ² to 4 mm ² , and/or two adjacent first flexible electrodes (2) The spacing between them is 0.1mm to 0.2mm. 8 . The flexible pressure sensor according to claim 1 , wherein the area occupied by the plurality of first flexible electrodes ( 2 ) is 0.6 cm ² to 1 cm ² . 9 . The flexible pressure sensor according to claim 1 , wherein the first flexible electrode ( 2 ) is square. 10 . 10. A pulse condition measuring device, characterized in that it comprises the flexible pressure sensor according to any one of claims 2-9 and a processor, wherein the processor is used to receive the digital data sent by the analog-to-digital conversion device (5). Signal.

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