Development of a Flexible Capacitive Tactile-Proximity Sensor Array With CMOS Integration for Enhanced Sensitivity

The integration of tactile and proximity sensors enhances our ability to perceive and interact with both touchable and touch-free objects within our environment. Flexible electronics technology, particularly in capacitive sensing, provides an ideal foundation for developing advanced tactile-proximity sensors. In this study, we present an integrated capacitive tactile-proximity sensor that combines with complementary metal-oxide-semiconductor (CMOS) readout circuitry to achieve enhanced sensitivity and system miniaturization. By utilizing four metal layers from two flexible substrates available through commercial technology, we efficiently fabricate an $8 \times 8$ tactile sensor array integrated with proximity sensing capabilities. Finite-element simulations are conducted to validate the measured data. Experiment results demonstrate that the tactile sensors achieve an average sensitivity of 2.2 MPa $^{-{1}}$ with a resolution of 255 Pa, while the proximity sensing exhibits a detection range of approximately 15 mm with a resolution better than $1.9 \; \mu $ m. These findings demonstrate the significant potential of flexible tactile-proximity sensors for applications requiring high sensitivity and precision in detection.