Organic optoelectronic diodes as tactile sensors for soft-touch applications

The distributed sense of touch forms an essential component that defines real-time perception and situational awareness in humans. Electronic skins are an emerging technology in conferring an artificial sense of touch for smart human-machine interfaces. However, assigning a conformably distributed sense of touch over a large area has been challenging to replicate in modern medical, social, and industrial robots. Herein, we present a new class of soft tactile sensors that exploit the mechanisms of triplet-triplet annihilation, exciton harvesting, and a small Stokes shift in conjugated organic semiconductors such as rubrene. By multiplexing the electroluminescence and photosensing modes, we show that a compact optoelectronic array of multifunctional rubrene/fullerene diodes can accurately measure pressure, position, and surface deformation applied to an overlying elastomeric layer. The dynamic range of sensing is defined by mechanical properties of the elastomer. Such optoelectronic approach paves the way for soft, conformal, and large-area compatible electronic skins for medicine and robotics.