A very high density floating electrode flexible sensor array for high-resolution measurements of contact forces

We present the development, fabrication and testing results of a new high-density flexible sensor array (HDFA) suitable of recording three-axis stresses with high spatial resolution. The new HDFA consists of 676 (26×26) sensing cells fabricated on top of a high-density flex circuit substrate. Each sensing cell is implemented using four floating comb electrodes separated from the flex substrate by a thin layer of a compressible PDMS film. Each sensing cell measures 2.77×2.55 mm2 thus packing 2704 capacitors in an area of ~ 50 cm2. The HDFA is read using a high-speed switched-capacitor circuit with a 13-bit resolution at full frame rates of 100 Hz (~0.8Mb/s). The new array is capable of detecting contact line displacements as low as 35 μm and contact line velocities as low as 38 μm/s.