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 x 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 x 140 m(2), 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.