CN111380632A

CN111380632A - Wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance

Info

Publication number: CN111380632A
Application number: CN202010132654.5A
Authority: CN
Inventors: 杨林; 于仕辉; 娄文涛; 秦国轩
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2020-02-29
Filing date: 2020-02-29
Publication date: 2020-07-07

Abstract

The invention discloses a wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance, LC resonance circuits are respectively printed on two sides of a flexible substrate, the flexible substrate is of an asymmetric structure, and planar spiral inductors on two sides respectively adopt a clockwise winding direction from inside to outside and a counterclockwise winding direction from inside to outside. The invention adopts a double-layer asymmetric LC resonance loop structure, and can optimize the detection distance and sensitivity of the wireless passive sensor based on LC resonance. The flexible substrate of Polydimethylsiloxane (PDMS) can meet the application requirements of wearable devices, electronic skins, medical detection and the like.

Description

Wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance

Technical Field

The invention relates to the field of flexible pressure sensors, in particular to a wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance.

Background

The flexible pressure sensor has the characteristics of small volume, high sensitivity, large bearable deformation and the like, and is well applied to important fields of electronic skin, medical detection, wearable equipment and the like. The existing capacitive flexible pressure sensor has the advantages of high sensitivity, quick dynamic response and the like, but all adopt an active structure, and a metal electrode needs to be sputtered on a flexible substrate, so that the problems of low working efficiency, high maintenance cost, high energy consumption and the like exist in practical application. Therefore, wireless and passive design is required to avoid the application defects of the current wired structure sensor and expand the application range of the sensor.

At present, the wireless and passive modes of the sensor are as follows: 1) the LC wireless passive technology establishes a connection with the planar spiral inductor through wireless coupling by the detection antenna to generate a resonant frequency; 2) in the Surface Acoustic Wave (SAW) technology, when a sensor is stressed, a piezoelectric substrate of the sensor generates SAW, and the magnitude of strain borne by the sensor can be analyzed according to different characteristics of front and rear waves; 3) radio Frequency Identification (RFID) technology, a radio frequency circuit is connected to a sensor. When the device works, a transmitter in a high-frequency module on the reader transmits a radio-frequency signal, a coupling element on the transponder receives energy to activate a data carrier module on the transponder, and then data is transmitted out through an antenna and received by a receiver to realize wireless detection. The latter two methods both require complex and expensive signal processing circuits, and compared with LC resonant devices, the LC resonant devices have the advantages of fewer manufacturing processes, good linearity, high sensitivity, simple signal processing circuits, low power consumption, and the like, so the LC resonant method is applied to flexible pressure sensors. However, the wireless passive technology of LC resonance has the problems of short measuring distance and low sensitivity.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance, which solves the problems of short measuring distance, low sensitivity and the like in the wireless passive technology of LC resonance in the prior art.

The technical scheme of the invention is as follows:

the utility model provides a wireless passive flexible pressure sensor based on double-deck asymmetric LC resonance, flexible basement both sides are printed LC resonance circuit respectively to for asymmetric structure, both sides plane spiral inductance adopts clockwise from inside to outside convolute direction and anticlockwise from inside to outside convolute direction respectively.

The flexible substrate is a polydimethylsiloxane material, and the dielectric constant of the flexible substrate is 2.7.

The flexible substrate has a length ×, width × and height 50 × 50 × 0.3.3 mm.

The planar spiral inductor has 7 turns of coils, and the total area is 30 × 30 mm.

The printing method is a screen printing method and is prepared by silver paste.

The invention has the beneficial effects that:

1. the invention adopts a double-layer asymmetric LC resonance loop structure, and can optimize the detection distance and sensitivity of the wireless passive sensor based on LC resonance.

2. The invention adopts the Polydimethylsiloxane (PDMS) flexible substrate, and can meet the application requirements of wearable devices, electronic skins, medical detection and the like.

3. The invention has simple structure and easy processing.

Drawings

FIG. 1 is a schematic structural view of a spiral inductor wound clockwise (from inside to outside) on one side of a flexible substrate according to the present invention;

FIG. 2 is a schematic view of the spiral inductor structure on the other side of the flexible substrate in a counterclockwise (from inside to outside) winding direction;

FIG. 3 is a graph comparing the S11 parameters of the present invention and a single layer LC tank.

Detailed Description

In order to make the object, technical solution and beneficial effects of the present invention more clearly understood, the following detailed description is made with reference to the accompanying drawings and embodiments.

Printing a clockwise (from inside to outside) winding planar spiral inductor on one side of a flexible substrate Polydimethylsiloxane (PDMS), and simultaneously printing a counterclockwise (from inside to outside) winding planar spiral inductor on the other side of the flexible substrate. The detection coil generates an alternating magnetic field which is coupled with asymmetric LC loops at the upper side and the lower side of the flexible substrate, so that the resonance frequency is generated on the detection coil. When the substrate is under the action of pressure, the farthest measurement distance of the detection coil is improved under the asymmetric double-layer LC structure, the offset of the resonance point is increased, and the measurement distance and the sensitivity of the wireless passive flexible pressure sensor based on the LC resonance circuit are effectively improved.

The upper layer clockwise (from inside to outside) winding plane spiral inductor structure is shown in figure 1, the lower layer anticlockwise (from inside to outside) winding plane spiral inductor structure is shown in figure 2, and the silver paste is prepared by adopting a screen printing method.

The substrate 1 is a flexible substrate PDMS, the upper layer is printed with a clockwise (from inside to outside) winding plane spiral inductor structure 2, and the lower layer is printed with a counterclockwise (from inside to outside) winding plane spiral inductor structure 3;

the flexible substrate 1 has a length ×, a width × and a height of 50 × 50 × 0.3.3 mm, and is made of Polydimethylsiloxane (PDMS) with a dielectric constant of 2.7.

The upper layer is wound to the planar spiral inductor 2 structure from inside to outside clockwise, the total area is 30 × 30mm, the width of the coil is 0.3mm, and the width of the coil gap is 0.3 mm.

The lower layer is wound to the planar spiral inductor 3 structure from inside to outside counterclockwise for 7 turns, the total area is 30 × 30mm, the width of the coil is 0.3mm, and the width of the coil gap is 0.3 mm.

FIG. 3 is a graph comparing the simulation of the resonant frequency of the single-layer LC resonant tank in this embodiment. The double-layer asymmetric LC resonant loop structure has a lower S11 parameter.

The invention is not limited to the embodiments described above, many variations in detail are possible without departing from the scope and spirit of the invention.

Claims

1. The wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance is characterized in that LC resonance circuits are printed on two sides of a flexible substrate respectively and are of asymmetric structures, and planar spiral inductors on two sides respectively adopt clockwise from inside to outside winding directions and anticlockwise from inside to outside winding directions.

2. The wireless passive flexible pressure sensor based on two-layer asymmetric LC resonance of claim 1, characterized in that the flexible substrate is a polydimethylsiloxane material with a dielectric constant of 2.7.

3. The wireless passive flexible pressure sensor based on two-layer asymmetric LC resonance as claimed in claim 1, wherein the flexible substrate has a length ×, a width × and a height 50 × 50, 50 × 0.3.3 mm.

4. The wireless passive flexible pressure sensor based on double-layer asymmetric LC resonance as claimed in claim 1, wherein the planar spiral inductor has 7 turns of coil, and the total area is 30 × 30 mm.

5. The wireless passive flexible pressure sensor based on the double-layer asymmetric LC resonance is characterized in that the printing method is a screen printing method and is prepared by silver paste.