Extremely Stretchable Fiber Transistors Based on the Programmable Inflow and Outflow of Semiconducting Fiber to an Ionic Liquid Phase

Fiber-like electronics have great advantages for wearable display, sensor, and optoelectronic applications due to their woven, flexible, stretchable, and conformable properties. Although recent research has focused on the stretchable fiber electronics, the limited performance stability under repeated expansion and contraction still needs to be improved. Inspired by the outflow and inflow behavior of spider’s capture threads to a wet liquid droplet to release an applied tension and maintain the orb web, we fabricate a novel woven-type transistor array including p-conjugated polymer- and metal-coated micro-fibers, respectively, as semiconductor and conductor, with patterned ionic liquid gels. Current level of each transistor is changed, by the inflow and outflow of the semiconductor fiber (with a diameter of 4 - 20 mm) to the ionic liquid gel droplet (Diameter = 200 - 600 mm), which is positioned at the junction between source/drain and semiconducting fibers. Electrical performance (charge carrier mobility, on and off current ratio) is optimized by tunning the fiber-liquid interfacial tension, liquid phase, device geometry, etc. The fiber transistor produces shows consistent stress-response drain current, originating from the elasto-capillarity inflow of the semiconductor segment to the ionic liquid phase below a critical tension. We believe that the self-recoverable fibers provide insight to achieve stretchable motion sensor and light emitting diode display.