Large-Scale Tactile Sensor Array Fabrication via Sequential Grayscale DLP Printing with High Spatial Resolution and Low Crosstalk

This work presents the fabrication of a large-area flexible matrix sensor array using a two-step sequential grayscale Digital Light Processing (sDLP) process. In this approach, digitally modulated masks enable a two-step exposure that forms 3D flexible microstructures in a single printing sequence, followed by the deposition of a resincarbon nanotube (CNT) conductive layer. A single sensor unit ($4.05 ~\text{mm} \times 4.05 ~\text{mm}$) was fabricated and tested across a broad pressure range ($1-3500 \text{kPa}$), exhibiting excellent linearity from 1 to$1500 \text{kPa}\left(\mathrm{R}^{2}=0.99\right)$and high sensitivity ($296.5 \text{kPa}^{-1}$). The device demonstrated rapid response times of 0.07 s under loading and 0.01 s during release. By tuning the grayscale mask values, this design was successfully scaled to a$16 \times 9$array (144 units), enabling large-scale fabrication via the two-step sDLP process. The array exhibited extremely low cross-talk (SNR$>99 ~\text{dB}$) and an effective spatial resolution of$\sim 5.98 ~\text{mm}$per pixel, enabling precise mapping of multiple simultaneous contacts with minimal interference.