Transparent and flexible organic field-effect transistor for multi-modal sensing

Multi-functional devices having responsiveness to multiple physical stimuli, mechanical flexibility and optical transparency are of great interest in applications for human-machine interfaces. Here we demonstrate transparent and flexible organic field effect transistor (tf-OFET) devices with multi-modal sensing capability of detecting infrared (IR) light, pressure, and strain simultaneously. The multi-modal sensing layer with piezoelectricity and pyroelectricity was directly integrated into OFETs as the gate dielectric so that a new type of multi-modal sensing device with simple structure having possibility of increasing the sensor cell density can be easily fabricated. For decoupling of pyro- and piezoelectric responses in a single device under simultaneous stimulations of IR exposure and strain, an approach of determining two input stimuli by separating the polarization changes inside the gate dielectric (V_o) and the modulation in the product of effective field-effect channel mobility and gate capacitance (μC). The high sensitivity of the devices to IR from human body may also enable the devices to be applied for the realization of artificial intelligence that contacts directly with human body such as artificial e-skin, biomedical monitoring, and tactile sensing.