Electroluminescent Pressure-Sensing Displays

Simultaneous sensing and visualization of pressure provides a useful platform to obtain information about a pressurizing object, but the fabrication of such interactive displays at the single-device level remains challenging. Here, we present a pressure responsive electroluminescent (EL) display that allows for both sensing and visualization of pressure. Our device is based on a two-terminal capacitor with six constituent layers: top electrode/insulator/hole injection layer/emissive layer/electron transport layer/bottom electrode. Light emission upon exposure to an alternating current field between two electrodes is controlled by the capacitance change of the insulator arising from the pressure applied on top. Besides capacitive pressure sensing, our EL display allows for direct visualization of the static and dynamic information of position, shape, and size of a pressurizing object on a single-device platform. Monitoring the pressurized area of an elastomeric hemisphere on a device by EL enables quantitative estimation of the Young's modulus of the elastomer, offering a new and facile characterization method for the mechanical properties of soft materials.