Flexible pressure sensors based on a multilevel microstructure: electrode configurations and array technologies

Abstract

With the development of smart wearables, medical electronics and robotics, flexible pressure sensors, as core sensing components, have demonstrated broad application prospects. Inspired by bionics, we found that the microstructure of Indocalamus leaves exhibits hierarchical distribution, which can undergo more sustained deformation under pressure and is expected to enhance device sensitivity in a broader pressure range. Flexible piezoresistive pressure sensors were fabricated by replicating this microstructure onto flexible PDMS substrates and using graphene nanoplatelet (GNP) films as the functional layers. In order to maximize the optimization effect of the microstructure and the pressure sensitivity of GNPs, we studied and compared two types of pressure sensors based on electrode structures normal to the plane (NP) of GNP films and in plane (IP) of the films. The NP sensors with microstructured substrates exhibit high sensitivity and a narrow pressure range, with device sensitivity reaching 16.18 kPa⁻¹ (0.136–6 kPa) and 11.48 kPa⁻¹ (6–17 kPa). The IP sensors with microstructured substrates demonstrate a better comprehensive performance, with sensitivity reaching 1.23 kPa⁻¹ (3–16 kPa), 3.88 kPa⁻¹ (16–40 kPa) and 8.41 kPa⁻¹ (40–60 kPa), and higher stability. Based on these two structures, we designed two types of electrode arrays and achieved array-distributed duplication of the microstructure using a pit compensation method, thereby fabricating pressure sensor arrays. Additionally, an arrayed voltage signal detection circuit and pressure signal mapping software were designed and developed to enable distributed pressure detection by the sensor arrays.