A 3D Composited Flexible Sensor Based on Percolative Nanoparticle Arrays to Discriminate Coupled Pressure and Strain

Abstract

Flexible mechanical sensors based on nanomaterials operate on a deformation-response mechanism, making it challenging to discern different types of mechanical stimuli such as pressure and strain. Therefore, these sensors are susceptible to significant mechanical interference. Here, we introduce a multifunctional flexible sensor capable of discriminating coupled pressure and strain without cross-interference. Our design involves an elastic cantilever fixed on the pillar of the flexible main substrate, creating a three-dimensional (3D) substrate, and two percolative nanoparticle (NP) arrays are deposited on the cantilever and main substrate, respectively, as the sensing materials. The 3D flexible substrate could confine pressure/strain loading exclusively on the cantilever or main substrate, resulting in independent responses of the two nanoparticle arrays with no cross-interference. Benefitting from the quantum transport in nanoparticle arrays, our sensors demonstrate an exceptional sensitivity, enabling discrimination of subtle strains down to 1.34 × 10−4. Furthermore, the suspended cantilever with one movable end can enhance the pressure perception of the NP array, exhibiting a high sensitivity of −0.223 kPa−1 and an ultrahigh resolution of 4.24 Pa. This flexible sensor with multifunctional design will provide inspiration for the development of flexible mechanical sensors and the advancement of decoupling strategies.

Strain/pressure sensors utilizing advanced nanomaterials

“…34 A double layer carbon-NP-based flexible pressure sensor was developed to reduce the relative random error and increase long-term accuracy and stability. 35 The proposed method of using a high frequency test signal instead of the conventional DC signal significantly reduced the relative random error of the sensor, making it more accurate and stable. 36,37 The sensor had a sensitivity of 0.024 kPa and a linear range of 0-4 kPa, making it suitable for applications such as respiratory measurement and arterial pulse measure.…”