Printable Ultrathin Metal Oxide Semiconductor-Based Conformal Biosensors

Abstract

Conformal bioelectronics enable wearable, noninvasive, and health-monitoring platforms. We demonstrate a simple and straightforward method for producing thin, sensitive In₂O₃-based conformal biosensors based on field-effect transistors using facile solution-based processing. One-step coating <i>via</i> aqueous In₂O₃ solution resulted in ultrathin (3.5 nm), high-density, uniform films over large areas. Conformal In₂O₃-based biosensors on ultrathin polyimide films displayed good device performance, low mechanical stress, and highly conformal contact determined using polydimethylsiloxane artificial skin having complex curvilinear surfaces or an artificial eye. Immobilized In₂O₃ field-effect transistors with self-assembled monolayers of NH₂-terminated silanes functioned as pH sensors. Functionalization with glucose oxidase enabled d-glucose detection at physiologically relevant levels. The conformal ultrathin field-effect transistor biosensors developed here offer new opportunities for future wearable human technologies.