FLEXIBLE ELECTRONICS Within touch of artificial skin

Several research groups have been developing flexible arrays of transducers that can be fabricated with pressure sensitivity and response times approaching those of natural human skin. One of the groups used Ge/Si-nanowire-array field-effect transistors (FET) laminated on a flexible polyimide substrate with a pressure-sensitive rubber layer that acts as a tunable resistor in series with the nanowire FET. Another group microstructured polydimethylsiloxane (PDMS) films to produce pressure-sensitive capacitor arrays that are integrated into the gate dielectrics of an organic FET array. Both report pressure sensors with response times of less than 100 ms and a dynamic range of 0.5-20 kPa or better. The incorporated sensors enable the detection of local temperature, the presence of light or electromagnetic fields, or even humidity levels. The addition of piezoelectric nanowire arrays may even help emulate the enhanced sensitivity provided by human hair follicles.