Printed Flexible Strain Sensor Array for Bendable Interactive Surface

An interactive surface using bending gestures as the input is proposed by integrating a flexible strain sensor array and a flexible display screen. To create such a flexible strain sensor array, formation of a reliable interconnection between the elastic sensitive regions and the rigid contact regions is vital to achieve required sensitivity and durability. In this work, a new design with an added interconnect layer on top of the interface regions is used to reduce the bending induced local stress. A stretchable conductive composite by blending carbon black (CB) with polydimethylsiloxane (PDMS) and Ecoflex (CB-PDMS/Ecoflex) is developed for the interconnect layer. CB-PDMS/Ecoflex is compatible with the blade coating for facile processing, and demonstrates a similar low Young's modulus as that of the sensitive region composed of silver nanowires and PDMS. Printing processes are developed to fabricate a 4 x 9 flexible strain sensor array based on the proposed design and the interconnect layer. It is shown that the sensor with CB-PDMS/Ecoflex interconnect layer can sustain more than 3000 bending cycles. Finally, the sensor array is integrated with a flexible active-matrix organic light-emitting diode display to construct the bendable interactive surface, demonstrating the capability of controlling the ball movement via bending gestures.