Surface Texture Detection With a New Sub-mm Resolution Flexible Tactile Capacitive Sensor Array for Multimodal Artificial Finger
Edoardo Sotgiu, D. Aguiam, Carlos Calaza, José Rodrigues, J. Fernandes, Bernardo J. Pires, Eurico Esteves Moreira, Filipe S. Alves, Hélder Fonseca, Rosana A. Dias, Sofia Martins, J. Gaspar
Abstract
This work presents a flexible polyimide-based capacitive tactile sensing array with sub-millimeter spatial resolution. The sensor is conceived to be embedded in a multimodal artificial finger to detect and classify the texture morphology of an object's surface. The proposed tactile sensor comprises a 16 × 16 array of capacitive sensing units. Each unit is composed of a parallel square electrode pairs (340 μm × 340 μm) separated by a compressible air cavity and embedded into a flexible polyimide substrate. Standard MEMS microfabrication techniques were used to develop the sensor. The polyimide device was covered with a thin compressible PDMS layer to tune the normal pressure sensitivity and dynamic range (225-430 μm thin PDMS layer resulting in 0.23-0.14 fF/kPa). The detection of the surface morphologies of a regular grating stamp for different orientation and a small metallic nut placed on the sensor is demonstrated, showing a 420 μm spatial resolution. The proposed sensor represents a novel capacitive tactile sensing device with a sub-mm resolution of human fingertip sensitivity.