Proton conducting sodium alginate electrolyte laterally coupled low-voltage oxide-based transistors

Solution-processed sodium alginate electrolyte film shows a high proton conductivity of ∼5.5 × 10−3 S/cm and a high lateral electric-double-layer (EDL) capacitance of ∼2.0 μF/cm2 at room temperature with a relative humidity of 57%. Low-voltage in-plane-gate indium-zinc-oxide-based EDL transistors laterally gated by sodium alginate electrolytes are fabricated on glass substrates. The field-effect mobility, current ON/OFF ratio, and subthreshold swing of such EDL transistors are estimated to be 4.2 cm2 V−1 s−1, 2.8 × 106, and 130 mV/decade, respectively. At last, a low-voltage driven resistor-load inverter is also demonstrated. Such in-plane-gate EDL transistors have potential applications in portable electronics and low-cost biosensors.