High-Resolution CMOS Tactile-Proximity Sensor Array: Design, Fabrication, and Performance Evaluation

Integrated circuit technologies provide an ideal platform for multisensor integration by leveraging well-established electronic processes. However, the integration of a large tactile sensor array with proximity sensing has not been extensively studied. In this article, we investigate the sensing capabilities of a
$32\times 32$
piezoresistive tactile sensor array with capacitive proximity sensing implemented using a complementary metal-oxide-semiconductor (CMOS) process. Capacitive electrodes, separated by
$175~\mu $
m, are conveniently implemented on top of the tactile pixels, each measuring
$140\times 140~\mu $
m2, using metallization layers. The sensing structures were fabricated using a wet metal etch, followed by an anisotropic silicon etch. In our experiments, the tactile sensors exhibited an average sensitivity of −0.084%/kPa with a resolution of 58 Pa. The proximity sensing displayed a detection range of approximately 0.9 mm, with a resolution better than
$1~\mu $
m. These results demonstrate the significant potential of CMOS tactile-proximity sensors for applications requiring sensitive detection.