Flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber double sensing intervals

Abstract

The invention discloses a flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber double sensing intervals. The sensor sequentially comprises a packaging layer, an electrode layer and a sensitive layer from outside to inside, the sensitive layer is formed by uniformly dispersing amorphous powder FeCrMoSiB subjected to heat treatment on porous silicone rubber, the electrode layer is made of copper foil, the packaging layer is made of PDMS, and the sensitive layer is formed by blending amorphous powder, ammonium bicarbonate and 107 silicone rubber through an open mill and then heating and curing; compared with a traditional piezomagnetic sensor, the piezomagnetic sensor can perform double-stress-interval sensing, namely, the piezomagnetic sensor not only has higher sensitivity to low stress, but also has good sensitivity to high stress; in addition, the preparation process is simple, the preparation cost is low, and adopted medicines are nontoxic and harmless.

Description

Technical Field

[0001] The present invention relates to the field of flexible pressure sensors, and in particular to a flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing intervals. Background Art

[0002] A sensor is a device or apparatus that can sense the information being measured and convert it into a usable output signal according to certain rules. With the rapid development of modern science and technology, the application of sensors has penetrated into various technical levels and fields, and people have put forward new requirements for sensors, namely small size, low power consumption, high sensitivity, low manufacturing cost and simple process.

[0003] However, currently, commonly used sensors at home and abroad generally have problems such as single sensing range and low sensitivity. The sensor in the present invention is based on the piezomagnetic effect of amorphous powder in silicone rubber, that is, the flexible piezomagnetic sensor based on the dual sensing range of amorphous powder / porous silicone rubber will deform under the action of external stress, resulting in changes in the internal magnetization state, and the measured impedance will change significantly. In addition, the micro-nano structure constructed by the ammonium bicarbonate foaming technology of the present invention makes the sensor not only have high sensitivity to low stress but also have good sensitivity to huge stress. Summary of the invention

[0004] The purpose of the present invention is to prepare a flexible piezomagnetic sensor with dual sensing intervals and high sensitivity in order to solve the problem of single sensing interval in existing sensors.

[0005] A flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing intervals includes, from the outside to the inside, a packaging layer, an electrode layer and a sensitive layer, wherein the sensitive layer is formed by heat-treated amorphous powder FeCrMoSiB uniformly dispersed on porous silicone rubber.

[0006] Preferably, the encapsulation layer is polydimethylsiloxane.

[0007] Preferably, the electrode layer is copper foil with a thickness of 0.01-0.014 mm.

[0008] Preferably, the thickness of the sensitive layer is 0.4-0.5 mm.

[0009] Preferably, the preparation steps of the heat-treated amorphous powder FeCrMoSiB are as follows: under vacuum conditions, the amorphous powder FeCrMoSiB is heat-treated at 550°C for 30 minutes, then mixed with a coupling agent having a mass fraction of 2%, ground for 20 minutes, and then dried at 80°C for 3 hours.

[0010] The method for preparing the above-mentioned flexible piezomagnetic sensor comprises the following steps:

[0011] (1) Heat treatment of amorphous powder FeCrMoSiB

[0012] Under vacuum conditions, the amorphous powder FeCrMoSiB was heat treated at 550°C for 30 min, then mixed with 2% by mass of a coupling agent, fully ground, and dried at 80°C for 3 hours.

[0013] (2) Preparation of sensitive layer

[0014] 80 parts by weight of heat-treated amorphous powder FeCrMoSiB, 20 parts by weight of 107 silicone rubber, 1-5 parts by weight of ammonium bicarbonate, 2 parts by weight of white carbon black, and 2 parts by weight of a vulcanizing agent are mixed for 3 hours, rolled into a thickness of 0.4-0.5 mm, and cured to obtain a sensitive layer;

[0015] (3) Packaging

[0016] First, a copper wire is welded on the electrode layer, and the electrode layer, the sensitive layer, and the electrode layer are placed in the mold in turn. PDMS and the curing agent are evenly mixed in a mass ratio of 10:1 and introduced into the above mold for curing. After curing, the mold is demolded to obtain the flexible piezomagnetic sensor.

[0017] Preferably, the coupling agent is isopropyl titanium triisostearate.

[0018] Preferably, grind for 20 minutes.

[0019] Preferably, the mass fraction of ammonium bicarbonate is 3-5 parts.

[0020] Preferably, in step (2), curing is performed at 145° C. for 1 h.

[0021] Preferably, in step (3), curing is performed at 65° C. for 6 hours.

[0022] Compared with the prior art, the advantages and effects of the present invention are

[0023] (1) Compared with existing sensors, the sensor of the present invention has a simple preparation process, uses low-cost raw materials, and uses an open mill for mixing. The technology is mature and suitable for industrial large-scale production.

[0024] (2) The sensor of the present invention can overcome the single sensing range problem of existing sensors, and has extremely high sensitivity (226MPa) in the low stress range (0-0.25MPa) -1 ), and has a high sensitivity (53.2MPa) in the high stress range (0.25-2.6MPa). -1). This is because there are a large number of micron-sized holes in the sensor, and the heat-treated amorphous powder FeCrMoSiB distributed therein forms a certain conductive network. Under low stress, a large number of micron-sized holes in the sensor will be closed, which will change the spatial arrangement of the heat-treated amorphous powder FeCrMoSiB and then change the conductive network structure, causing the resistance and magnetic properties of the film to change, and finally produce a larger stress impedance response. In the high stress range, most of the micron-sized holes in the sensor are closed, resulting in an increase in its modulus, which enables it to withstand higher compressive stress.

[0025] (3) The micro-nano porous structure constructed by the ammonium bicarbonate foaming technology of the present invention enables the sensor to perform dual stress interval sensing, and the cost of the ammonium bicarbonate raw material is low and the foaming process is simple.

[0026] (4) The base material 107 silicone rubber used in the present invention accounts for 20% of the sensor. 107 silicone rubber is a low-priced raw material, which reduces the overall cost of the sensor. Its high performance meets market demand, and its high cost performance conforms to market rules, and has broad commercial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing interval.

[0028] Figure 2 This is a scanning electron microscope image of the cross-section of the sensitive layer based on amorphous powder / porous silicone rubber composite film.

[0029] Figure 3 This is the sensitivity diagram of the flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing range in the low stress range and high stress range.

[0030] Figure 4 This is a graph showing the impedance signal changes when a flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing interval is pasted on the end of a finger to grasp different weights.

[0031] Figure 5 The stress-impedance ratio response diagram of the sensor prepared by adding different mass fractions of ammonium bicarbonate. DETAILED DESCRIPTION

[0032] The present invention is described in detail below.

[0033] Combination Figure 1The present invention constructs a flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing interval, which includes, from outside to inside, an encapsulation layer PDMS, an electrode layer copper foil and a sensitive layer amorphous powder / porous silicone rubber, wherein the sensitive layer is composed of heat-treated amorphous powder FeCrMoSiB uniformly dispersed on porous silicone rubber. The amorphous powder constructs a certain conductive network in the porous silicone rubber. The structure of the conductive network of the porous silicone rubber will change under the action of compressive stress, thereby changing the resistance and magnetic properties of the film, making the impedance respond more obviously. The porous structure in the silicone rubber will make the conductive network structure constructed by the amorphous powder more sensitive to stress, that is, the appearance of the porous structure will cause the conductive network to undergo a large change under low stress, thereby causing a huge change in the resistance and magnetic properties of the film, making the impedance respond more obviously.

[0034] Comparative Example 1

[0035] Preparation of flexible piezomagnetic sensors based on amorphous powder / silicone rubber with non-porous structure:

[0036] Step 1: Place the commercially available FeCrMoSiB micron amorphous powder into a round-bottomed capillary tube with an outer diameter of 20 mm, an inner diameter of 18 mm, a wall thickness of 1 mm, and a length of 16 cm, then turn on the mechanical pump to evacuate for 5 minutes, perform processing and tightening and sealing the tube to isolate the air, and then place it in a muffle furnace for heat treatment at 550°C for 30 minutes. Subsequently, the heat-treated amorphous powder is mixed with a coupling agent (isopropyl titanium triisostearate) with a mass fraction of 2% and ground in an agate mortar for 20 minutes, and finally the ground amorphous powder is placed in a constant temperature forced air drying oven and dried at 80°C for three hours.

[0037] Step 2: 80 parts by weight of the amorphous powder heat-treated in step 1, 20 parts of 107 silicone rubber, 2 parts of white carbon black, and 2 parts of a vulcanizing agent are mixed together in an open mill for three hours to be fully mixed, and then the spacing between the rollers of the open mill is adjusted to 0.4-0.5 mm, and the mixed film is rolled into a thickness of 0.4-0.5 mm, and finally placed in a constant temperature forced air drying oven at 145°C for curing for 1 hour to obtain a non-porous sensitive layer.

[0038] Step 3: Use 0.14mm copper foil as the upper and lower electrode layers of the sensor, and solder a 20cm long copper wire on the copper foil with an adjustable constant temperature electric soldering iron. Cut the copper foil, the non-porous sensitive layer, and the copper foil into 1cm*1cm sizes and put them into the mold in turn, then mix the PDMS and curing agent in a ratio of 10:1 in a magnetic stirrer for 1h to fully mix the PDMS and curing agent, finally pour it into the mold and put it in a constant temperature blast drying oven for drying, the curing temperature is 65℃, the curing time is 6h, and demolding is performed after curing is completed.

[0039] Impedance Analyzer (LCR Meter IM3536 made by HIOKI) and Electronic Universal Tester (UTM4304GD made

[0040] The performance of the sensor was tested by SUNS and the results are listed in Table 1.

[0041] Example 1

[0042] Preparation of flexible piezomagnetic sensor with dual sensing intervals based on amorphous powder / porous silicone rubber with 1 part of ammonium bicarbonate added:

[0043] Step 1: Place the commercially available FeCrMoSiB micron amorphous powder into a round-bottomed capillary tube with an outer diameter of 20 mm, an inner diameter of 18 mm, a wall thickness of 1 mm, and a length of 16 cm, then turn on the mechanical pump to evacuate for 5 minutes, perform processing and tightening and sealing the tube to isolate the air, and then place it in a muffle furnace for heat treatment at 550°C for 30 minutes. Subsequently, the heat-treated amorphous powder is mixed with a coupling agent (isopropyl titanium triisostearate) with a mass fraction of 2% and ground in an agate mortar for 20 minutes, and finally the ground amorphous powder is placed in a constant temperature forced air drying oven and dried at 80°C for three hours.

[0044] Step 2: 80 parts by weight of the amorphous powder heat-treated in step 1, 20 parts of 107 silicone rubber, 1 part of ammonium bicarbonate, 2 parts of white carbon black, and 2 parts of vulcanizing agent are mixed together in an open mill for three hours and fully mixed. Then, the spacing between the rollers of the open mill is adjusted to 0.4-0.5 mm, and the mixed film is rolled into a thickness of 0.4-0.5 mm. Finally, it is placed in a constant temperature forced air drying oven at 145°C for curing for 1 hour. During the curing process, the ammonium bicarbonate will be thermally decomposed to form a porous structure in the 107 silicone rubber.

[0045] Step 3: Use 0.14mm copper foil as the upper and lower electrode layers of the sensor, and solder a 20cm long copper wire on the copper foil with an adjustable constant temperature electric soldering iron. Cut the copper foil, sensitive layer, and copper foil into 1cm x 1cm sizes and put them into the mold in turn, then mix PDMS and curing agent in a ratio of 10:1 in a magnetic stirrer for 1h to fully mix PDMS and curing agent, finally pour it into the mold and put it into a constant temperature blast drying oven for drying, the curing temperature is 65℃, the curing time is 6h, and demolding is performed after curing is completed.

[0046] Impedance Analyzer (LCR Meter IM3536 made by HIOKI) and Electronic Universal Tester (UTM4304GD made

[0047] The performance of the sensor was tested by SUNS and the results are listed in Table 1.

[0048] Example 2

[0049] Preparation of flexible piezomagnetic sensor with dual sensing interval based on amorphous powder / porous silicone rubber with 3 parts of ammonium bicarbonate added:

[0050] The rest is the same as in Example 1, except that the mass fraction of ammonium bicarbonate is changed from 1 part to 3 parts to obtain the flexible piezomagnetic sensor.

[0051] Impedance Analyzer (LCR Meter IM3536 made by HIOKI) and Electronic Universal Tester (UTM4304GD made

[0052] The performance of the sensor was tested by SUNS and the results are listed in Table 1.

[0053] Example 3

[0054] Preparation of flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing interval with 5 parts of ammonium bicarbonate added:

[0055] The other parts are the same as in Example 1, except that the mass fraction of ammonium bicarbonate is changed from 1 to 5, and the flexible piezomagnetic sensor is obtained. The cross-sectional scanning electron microscope image of the sensitive layer is as follows: Figure 2 As shown. The sensitive layer of the sensor prepared by this method has a micro-nano porous structure ( Figure 2 ), the production of this structure greatly improves the sensitivity of the sensor in the present invention and gives it the characteristic of dual stress range sensing. The porous structure in the silicone rubber will make the conductive network structure constructed by the amorphous powder more sensitive to stress, that is, the appearance of the porous structure will cause a large change in the conductive network under low stress, thereby causing a huge change in the resistance and magnetic properties of the film, resulting in a more obvious impedance response.

[0056] Impedance Analyzer (LCR Meter IM3536 made by HIOKI) and Electronic Universal Tester (UTM4304GD made

[0057] by SUNS) to test the performance of sensors, such as Figure 3 As shown in the figure, in the low stress range, the micro-nano pore structure in the sensitive layer will close quickly, causing the arrangement position and distance of the soft magnetic amorphous powder in the sensitive layer to change rapidly, thus causing the magnetization state to change and the measured impedance value to change significantly. When in the high stress range, most of the micro-nano pores in the sensitive layer are closed, causing the elastic modulus of the sensitive layer to increase significantly, so that it can be sensed in a larger stress range. The results are listed in Table 1.

[0058] Figure 4The flexible piezomagnetic sensor was pasted on the fingertips to grab an empty beaker, a beaker with 200ml of water, and a beaker with 400ml of water, which produced impedance changes of 10%, 20%, and 30% respectively, and obvious impedance gradient changes could be seen.

[0059] Table 1

[0060]

[0061] Figure 5 The stress-impedance ratio response diagrams of the sensors prepared by adding different mass fractions of ammonium bicarbonate to the comparative example and Examples 1-3 are also given. It can be seen that the sensitivity of Example 3 is significantly higher than that of the comparative example and has an obvious dual sensing range.

Claims

1. A flexible piezomagnetic sensor based on amorphous powder / porous silicone rubber dual sensing interval, It is characterized in that From the outside to the inside, it includes a packaging layer, an electrode layer and a sensitive layer in sequence, wherein the sensitive layer is formed by heat-treated amorphous powder FeCrMoSiB uniformly dispersed on porous silicone rubber.

2. The flexible piezomagnetic sensor according to claim 1, It is characterized in that The encapsulation layer is polydimethylsiloxane.

3. The flexible piezomagnetic sensor according to claim 1, It is characterized in that The electrode layer is copper foil with a thickness of 0.01-0.014mm.

4. The flexible piezomagnetic sensor according to claim 1, It is characterized in that The thickness of the sensitive layer is 0.4~0.5mm.

5. The flexible piezomagnetic sensor according to claim 1, It is characterized in that The preparation steps of heat-treated amorphous powder FeCrMoSiB are as follows: under vacuum conditions, the amorphous powder FeCrMoSiB is heat-treated at 550°C for 30 min, then mixed with a coupling agent with a mass fraction of 2%, ground for 20 min, and then dried at 80°C for 3 hours.

6. A method for preparing a flexible piezomagnetic sensor according to any one of claims 1 to 5, It is characterized in that The steps include: (1) Heat treatment of amorphous powder FeCrMoSiB Under vacuum conditions, the amorphous powder FeCrMoSiB was heat treated at 550 °C for 30 min, mixed with 2% by mass of coupling agent, fully ground and dried at 80 °C for 3 hours. (2) Preparation of sensitive layer 80 parts by weight of heat-treated amorphous powder FeCrMoSiB, 20 parts by weight of 107 silicone rubber, 1-5 parts by weight of ammonium bicarbonate, 2 parts by weight of white carbon black, and 2 parts by weight of a vulcanizing agent are mixed for 3 hours, rolled into a thickness of 0.4-0.5 mm, and cured to obtain a sensitive layer; (3) Packaging First, a copper wire is welded on the electrode layer, and the electrode layer, the sensitive layer, and the electrode layer are placed in the mold in turn. PDMS and the curing agent are evenly mixed in a mass ratio of 10:1 and introduced into the above mold for curing. After curing, the mold is demolded to obtain the flexible piezomagnetic sensor.

7. The method according to claim 6, It is characterized in that The coupling agent is isopropyl titanium triisostearate.

8. The method according to claim 6, It is characterized in that The mass fraction of ammonium bicarbonate is 3-5 parts.

9. The method according to claim 6, It is characterized in that In step (2), the curing is carried out at 145°C for 1 h.

10. The method according to claim 6, It is characterized in that In step (3), the mixture is cured at 65°C for 6 h.

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