Overcoming Debye Length Limitations in Electrolyte‐Gated Transistor Biosensors Using Nanoscale‐Grooved Oxide Semiconductors Fabricated by Thermal Nanoimprint Lithography

ABSTRACT Electrolyte‐gated transistor (EGT) biosensors enable rapid, label‐free biomolecule detection but are hindered by the severe Debye screening effect in physiological ionic environments. Here, we present a facile, practical, and widely deployable strategy to overcome Debye length limitations by integrating nanoscale‐grooved indium gallium oxide (IGO) semiconductors into EGTs. Using sol–gel spin‐coating and thermal nanoimprint lithography with CD/DVD templates, we fabricate IGO films with precisely defined concave and convex nanostructures, demonstrating wafer‐scale patterning feasibility. These grooves modulate electric double‐layer formation by suppressing counterion accumulation, thereby extending the effective Debye length. As a result, the nanopatterned EGTs exhibit stable operation and ultrasensitive Tau detection from 1 × 10 −15 to 1 × 10 −10 m , even in 1× phosphate‐buffered saline, where planar devices show negligible response. Finite‐element method calculations further reveal geometry‐dependent electrostatic potential profiles and Debye lengths, validating the mechanistic origin of significantly enhanced sensitivity. Collectively, these results establish nanoscale patterning of amorphous oxide semiconductors as a powerful strategy to mitigate Debye screening limitations and provide an effective alternative to traditional ionic dilution techniques. Beyond Tau detection, this approach lays the foundation for next‐generation diagnostic systems integrating ultrasensitivity, reproducibility, and compatibility with complex biological environments, advancing practical point‐of‐care and precision healthcare applications.