Flexible resistive pressure sensor based on gradient atomic layer fracture and preparation method thereof

Abstract

The invention discloses a flexible pressure sensor based on an atomic layer fracture effect, which is characterized in that a gradient coating layer is constructed on a flexible substrate through an ALD (atomic layer deposition) and magnetron sputtering synergistic process, and high-sensitivity resistance detection is realized by using pressure-induced microcrack propagation. Compared with a traditional scheme, the sensitivity of the sensor is improved by 5 times, the manufacturing cost is reduced by 60%, and the sensor is suitable for medical monitoring, robot touch and other scenes.

Description

Technical Field The present invention relates to the field of flexible electronic technology, and in particular to a pressure sensor that achieves gradient coating through a collaborative process of atomic layer deposition (ALD) and magnetron sputtering, and utilizes resistance changes caused by fracture of the coating layer to achieve pressure detection. Background Art 1. Deficiencies in existing technology - Traditional pressure sensors rely on silicon-based piezoresistive materials, which have problems such as low sensitivity (0.1-1% FSR), poor flexibility, and high manufacturing costs.

[0001] - Existing flexible sensors mostly use carbon nanotube / graphene composite materials, but there are problems such as complex processing and poor signal linearity.

[0002] 2. Technological gaps There has been no report on regulating the atomic layer fracture threshold through a gradient coating structure and combining it with ALD precision coating to achieve high-sensitivity flexible pressure sensing. Summary of the Invention

[0003] 1. Technical Solution - Gradient coating structure: On a polyimide substrate, TiN (50nm) → Al2O3 (30nm) → organic silicon hybrid layer (10nm) are deposited in sequence to form a heterogeneous structure with decreasing hardness.

[0004] - Fracture control mechanism: By controlling the magnetron sputtering process parameters (power 50-200W, gas pressure 0.1-1Pa), a micro-crack network is preset in the coating layer. Under the action of pressure, the cracks expand, resulting in a jump in resistance.

[0005] - Signal detection system: Integrated Wheatstone bridge circuit, real-time acquisition of resistance changes and conversion into 0-10kPa pressure signal with a resolution of 50Pa.

[0006] 2. Innovation - Combining ALD with magnetron sputtering for the first time to achieve nanoscale thickness gradient control (error <±3%); - Using coating layer fracture to replace traditional piezoresistive materials, the sensitivity is increased to 5% FSR; - Uses a crisscross coating path to enhance the isotropy of mechanical response. DETAILED DESCRIPTION 1. Material selection - Substrate: polyimide (thickness 100μm, bendable radius <5mm); - Coating materials: TiN (conductive layer), Al2O3 (dielectric layer), PDMS-SiO2 hybrid layer (flexible transition layer).

[0007] 2. Process steps - Step 1: Substrate plasma cleaning (Ar gas, power 300W, time 5min); - Step 2: ALD deposition of Al2O3 layer (precursor TMA / H2O, 200 cycles); - Step 3: Magnetron sputtering of TiN layer (target purity 99.99%, gas pressure 0.5Pa); - Step 4: UV curing of the silicone layer (wavelength 365nm, intensity 50mW / cm²).

[0008] 3. Performance Testing - Pressure sensitivity: 5.2% FSR (0-10kPa), response time <0.1ms; - Cycle life: 10 6 The resistance drift after one pressure cycle is <3%.

Claims

1. A flexible pressure sensor, characterized in that The invention comprises: a flexible substrate, a gradient coating layer composed of at least three layers of heterogeneous materials, and an electrode array for detecting resistance changes caused by fracture of the coating layer.

2. - The thickness of the gradient coating layer is 50-100nm, and the hardness difference between adjacent layers is ≥20%; - The electrode array adopts an Ag nanowire grid structure with a line width of ≤10μm.