Symmetrically Ion‐Gated In‐Plane Metal‐Oxide Transistors for Highly Sensitive and Low‐Voltage Driven Bioelectronics

To provide a unique opportunity for on‐chip scaled bioelectronics, a symmetrically gated metal‐oxide electric double layer transistor (EDLT) with ion‐gel (IG) gate dielectric and simple in‐plane Corbino electrode architecture is proposed. Using amorphous indium‐gallium‐zinc oxide (a‐IGZO) semiconductor and IG dielectric layers, low‐voltage driven EDLTs with high ionotronic effects can be realized. More importantly, in contrast to the conventional asymmetric rectangular EDLTs which can cause non‐uniform potential variation in the active channel layer and eventually degrade the sensing performance, the new symmetrical in‐plane type EDLTs achieve high and spatially uniform ion responsive behaviors. The symmetrically gated a‐IGZO EDLTs exhibited a responsivity of 129.4% to 5 ppm mercury (Hg(2+)) ions which are approximately three times higher than that with conventional electrode structure (responsivity of 38.5%). To confirm the viability of the new device architectures and the findings, the detailed mechanism of the symmetric gating effects in the in‐plane EDLTs with a variety of electrical characterization and 3D fine element analysis simulations is also discussed.