Investigating Mechanical and Electrical Properties in Curved Touch Panels With an Innovative Ring ITO Electrode Structure Using an Optical-Flow Algorithm

Abstract

The flexible touch panel has attracted considerable attention due to its thin, bendable, and impact-resistant characteristics. However, applying touch functionality on curved surfaces has been limited by conventional indium tin oxide (ITO) electrodes, which suffer from light obstruction caused by mesh deformation during bending. To overcome this limitation, this study introduces a novel ring-shaped ITO electrode structure designed to improve optical transmittance. The mechanical behavior of the electrode under different curvatures and touch locations was analyzed using a 3-D optical-flow (OF) algorithm, while capacitance measurements were conducted to evaluate the corresponding electrical properties. Experiments were performed under curved conditions with varying touch positions to investigate the coupled mechanical-electrical response of the electrode. Stress and capacitance variations were further examined across different bending radii, touch locations, and repeated folding cycles. When the applied force increased to 150 g at the top, middle, and bottom positions, repeated folding-induced electrode stress, with a maximum rise of 38.13 MPa observed after 11 000 cycles. Meanwhile, the capacitance of adjacent electrodes exhibited a maximum change of 32 fF, confirming that the electrical response correlated with the stress evolution observed during touch testing.