Crack sensor based on large strain range and high sensitivity of metallic glass

Abstract

The crack sensor based on metal glass large strain range high sensitivity comprises, from bottom to top, an insulating layer, an adhesion layer, a metal glass layer and a crack silver film; the insulating layer is formed by deposition on a strain detection part through a magnetron sputtering mode; the adhesion layer is formed by deposition of metal titanium on the surface of the insulating layer through a magnetron sputtering mode; the metal glass layer is deposited on the surface of the adhesion layer through a sputtering mode; and the crack silver film is prepared by sputtering a metal silver film on the surface of the metal glass layer in a pre-compressed state and releasing the strain to prepare the crack silver film. The crack sensor can be prepared in situ and conformally, has strong adhesion to the substrate, good sensitivity, can effectively convert the generated strain into resistance change, and has great practical production significance.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a high-sensitivity crack sensor based on a large strain range of metallic glass. Background Technology

[0002] In recent years, thin-film strain sensors have attracted great attention due to their size characteristics and application scenarios, and are often used for safety and health monitoring of various high-precision equipment.

[0003] Despite the rapid development of thin-film strain sensors, strain sensing of metallic materials is often based on resistance changes caused by strain localization and necking effects. High-sensitivity metallic strain sensors are prone to cracking due to material properties, leading to irreversible degradation of sensor performance. While flexible and stretchable strain sensors can solve both low and high strain levels, the elastic substrate they use is not ideal for complex applications due to its adhesive bonding method. Summary of the Invention

[0004] The purpose of this invention is to enable the in-situ fabrication of a flexible crack sensor based on metallic glass on devices that require large strain operation. This sensor has good adhesion and can achieve good sensitivity at large strain levels.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The high-sensitivity crack sensor based on large strain range of metallic glass includes, from bottom to top, an insulating layer, an adhesion layer, a metallic glass layer, and a cracked silver film. The insulating layer is deposited on the strain to be detected by magnetron sputtering. The adhesion layer is deposited on the surface of the insulating layer by magnetron sputtering. The metallic glass layer is deposited on the surface of the adhesion layer by sputtering. The cracked silver film is prepared by sputtering a metallic silver film on the surface of the metallic glass layer under pre-compression, and then releasing the strain to prepare the cracked silver film.

[0007] The insulating layer is formed by alternating deposition of aluminum oxide and silicon dioxide.

[0008] The preparation of the insulating layer includes the following steps:

[0009] 1) The device was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, then the surface was purged with nitrogen and dried by heating.

[0010] 2) Place the device in a plasma cleaner, using oxygen as the cleaning gas, to clean the metal surface and remove surface stains.

[0011] 3) Insulating layers were deposited alternately on the sample surface in sequence. Alumina 0.25 μm and silicon dioxide 0.25 μm were deposited by magnetron sputtering, and the deposition was repeated 4 to 8 times. The overall thickness of the insulating layer was 2 to 4 μm.

[0012] The thickness of the adhesion layer is 5–20 nm.

[0013] The metallic glass layer is a Mg-based, La-based, or Zr-based alloy.

[0014] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0015] This invention provides a crack sensor based on magnetron sputtering technology, exhibiting excellent in-situ fabrication adhesion capabilities. Compared to traditional crack sensor structures that fabricate silver as a metallic strain layer on elastic substrates such as PDMS, amorphous alloys, due to their long-range disordered structure, also possess high strength, hardness, and stiffness, maintaining conductive pathways under large strain. When the sensor undergoes significant tensile strain, the silver layer fractures due to its lower fracture strength, while the cracks are connected by the metallic glass layer, achieving high sensitivity under large strain conditions, which has significant practical implications for production. Attached Figure Description

[0016] Figure 1 A process flow diagram for the high-sensitivity crack sensor based on large strain range of metallic glass provided by the present invention;

[0017] Figure 2 The film structure diagram provided by this invention is a high-sensitivity crack sensor based on a large strain range of metallic glass.

[0018] Figure 3 A schematic diagram of the state of a high-sensitivity crack sensor based on a large strain range of metallic glass before tensile testing, provided by the present invention.

[0019] Figure 4 This is a schematic diagram of the state of a high-sensitivity crack sensor based on a large strain range of metallic glass after stretching, as provided by the present invention.

[0020] Figure reference numerals: 1 is the device substrate; 2 is the insulating layer; 3 is the photomask; 4 is the adhesion layer; 5 is the metallic glass layer; 6 is the cracked silver film. Detailed Implementation

[0021] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] See Figures 1-2The present invention provides a high-sensitivity crack sensor based on a large strain range of metallic glass, comprising in-situ sputtering deposition of an insulating layer 2 on the surface of a device substrate 1 operating under large strain, and sequentially sputtering an adhesion layer 4, a metallic glass layer 5, and a crack silver film 6 on the surface of the insulating layer 2 by sputtering deposition.

[0023] The preparation method of the present invention is as follows:

[0024] 1. Preparation of insulating layer 2:

[0025] 1.1) The device was ultrasonically cleaned for 10 minutes each with acetone, anhydrous ethanol, and deionized water, then the surface was cleaned with nitrogen and dried by heating.

[0026] 1.2) In a plasma cleaner, the cleaning gas is oxygen, which is used to clean the metal surface and remove surface stains.

[0027] 1.3) Insulating layers were deposited alternately on the sample surface in sequence. Alumina (0.25 μm) and silicon dioxide (0.25 μm) were deposited by magnetron sputtering four times each, with an overall insulating layer thickness of 2 μm.

[0028] 2. A flexible mask 3 is attached to the surface of the sample with the deposited insulating layer to achieve in-situ deposition patterning;

[0029] 3. An adhesion layer 4 is deposited by magnetron sputtering. The adhesion layer is a titanium layer with a thickness of 20 nm to improve adhesion.

[0030] 4. Reduce the deposition rate of alloy metal by magnetron sputtering and deposit a high-strength metallic glass layer in situ. 5. In this embodiment, a Zr-based alloy is used as the metallic glass layer. The cooling rate is increased by magnetron sputtering, which reduces the generation of crystal nuclei and makes the sputtered alloy in an amorphous state.

[0031] 5. The sample is deformed by the fixture and is in a pre-compressed state. A cracked silver film is deposited by magnetron sputtering. 6. The fixture is released to allow the sample to return to its initial state. The silver cracks due to stretching, while the metallic glass does not crack due to its high strength. Finally, the mask is peeled off.

[0032] It should be noted that metallic glasses, due to their disordered structure, also possess high strength, hardness, and stiffness. The maximum elastic strain of amorphous alloys can reach 2.2%, while the elastic limit of traditional crystalline materials is typically less than 0.5%. Therefore, amorphous alloys have a higher elastic specific work, enabling them to remain crack-free even after subjected to increased strain.

[0033] In this invention, the cracked silver film 6 is formed by sputtering. The cracked silver film is deposited on the high-strength metallic glass layer 5 deposited in situ. Therefore, if the device substrate 1 is stretched again, the resistance of the metallic glass layer 5 increases due to the necking effect, the cracked silver film 6 breaks, and the resistance increases; when the stretching is released, the cracked silver film reconnects, and the resistance recovers.

[0034] For this invention, based on a high-sensitivity crack sensor with a large strain range in metallic glass, it is first necessary to explain the existing well-known principle of resistance change: Ohm's law is... ρ is the material resistivity, L is the material length, and s is the material cross-sectional area. In this invention, L specifically refers to the sensor length, and s specifically refers to the area of ​​the silver-connected area at the crack. When the sample is stretched, by Figure 3 , Figure 4 As shown, as the sensor length increases (L), cracks form, and strain gauge (s) decreases, thus increasing the resistance (R). The presence of the crack microstructure further exacerbates the change in s, causing the resistance (R) to change even more rapidly, thereby increasing the sensor's sensitivity. Under high strain conditions, the crack exists as independent regions. The high-strength metallic glass layer constructs a conductive network between these independent crack regions, enabling a significant breakthrough in the measurement range of the crack strain sensor.

[0035] This invention features strong adhesion, employs a sputtering deposition process, exhibits excellent conformal capability, and enables in-situ fabrication. It also boasts high sensitivity and a large range; the crack sensor exhibits extremely high sensitivity, and due to the additional high-strength metallic glass layer, the electrical path remains connected even after significant deformation.

[0036] As can be seen from the technical solution provided by this invention, compared with the prior art, this invention provides a crack sensor based on magnetron sputtering technology, which has good in-situ fabrication adhesion capabilities. Compared with the fabrication of highly sensitive silver or platinum metal strain layers on elastic substrates, amorphous alloys, due to their disordered structure, also possess high strength, hardness, and high stiffness. When the sensor undergoes large strain tension, the silver film fractures due to its low fracture strength, while the cracks are connected by the metallic glass layer, thus maintaining high sensitivity under large strain conditions, which has significant practical implications for production.

Claims

1. A high-sensitivity crack sensor based on a large strain range of metallic glass, characterized in that: The structure comprises, from bottom to top, an insulating layer, an adhesion layer, a metallic glass layer, and a cracked silver film. The insulating layer is deposited on the area where strain needs to be detected by magnetron sputtering. The adhesion layer is deposited on the surface of the insulating layer by magnetron sputtering. The metallic glass layer is deposited on the surface of the adhesion layer by sputtering. The cracked silver film is prepared by sputtering a metallic silver film on the surface of the metallic glass layer under pre-compression, and then releasing the strain to form the cracked silver film.

2. The high-sensitivity crack sensor based on large strain range of metallic glass as described in claim 1, characterized in that: The insulating layer is formed by alternating deposition of aluminum oxide and silicon dioxide.

3. The high-sensitivity crack sensor based on large strain range of metallic glass as described in claim 1, characterized in that: The preparation of the insulating layer includes the following steps: 1) The device was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, then the surface was purged with nitrogen and dried by heating. 2) Place the device in a plasma cleaner, using oxygen as the cleaning gas, to clean the metal surface and remove surface stains. 3) Insulating layers were deposited alternately on the sample surface in sequence. Alumina 0.25 μm and silicon dioxide 0.25 μm were deposited by magnetron sputtering, and the deposition was repeated 4 to 8 times. The overall thickness of the insulating layer was 2 to 4 μm.

4. The high-sensitivity crack sensor based on large strain range of metallic glass as described in claim 1, characterized in that: The thickness of the adhesion layer is 5–20 nm.

5. The high-sensitivity crack sensor based on large strain range of metallic glass as described in claim 1, characterized in that: The metallic glass layer is a Mg-based, La-based, or Zr-based alloy.

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