Self-Powered Tactile Pressure Sensors Using Ordered Crystalline ZnO Nanorods on Flexible Substrates Toward Robotic Skin and Garments

Flexible, bendable tactile pressure sensors are developed with crystalline ZnO nanorods as a robotic skin or as part of a multimodal sensing garment. The sensors are arranged in addressable arrays for detection of spatial tactile pressure variation with a resolution of 1 mm or better. The sensors are fully conformable to nonplanar surfaces. A low-temperature hydrothermal process in conjunction with thermal nanoimprint lithography is demonstrated to achieve ordered growth of ZnO nanorods placed vertically on the flexible substrate. The nanorods are fully packaged in inert polyimide for protection against dust, moisture, and mechanical shock. The sensor response to applied pressure is observed to be nearly linear and with negligible hysteresis. A peak sensitivity of 21.2 μV/kPa has been observed for tactile pressure in the 10-200 kPa range.