Ultra-Fast and Scalable Microfabrication of Flexible Tactile Sensors via Sequential Digital Light Processing

This paper introduces an ultra-fast and scalable method for fabricating tactile sensors within seconds using sequential digital light processing (sDLP) 3D printing. The process involves two UV exposure steps: (1) printing a flexible microstructure and (2) printing a thin conductive layer. The flexible microstructure made from TPU resin, serving as the transducer, is printed in just 6 seconds, followed by the resin-CNT active layer as a conductive layer which is printed within 500 seconds. The miniaturized sensor <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(5\times 5\text{mm}^{2})$</tex>, smaller than a fingertip, can detect pressures ranging from 50 kPa to 320 kPa, with sensitivities of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$121.7 \ \text{kPa}^{-1}$</tex> in the low-pressure range and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$30 \ \text{kPa}^{-1}$</tex> in the high-pressure range, both exhibiting excellent linearity <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{R}^{2}=0.99)$</tex>. The sensor provides a rapid response time of 10 ms and 20 ms during loading and unloading. This scalable approach enables the fabrication of a 7x4 sensor matrix within seconds, capable of accurateIy detecting varying pressure magnitudes and locations. Furthermore, we demonstrate the integration of the tactile sensor array with a microcontroller, enabling precise tactile feedback sensing on both flat, hard surfaces and curved, soft surfaces. This advancement opens new possibilities for enhancing robotic touch capabilities and improving human-machine interactions in a wide range of applications.