Digitally Printed Gold Nanoelectronics for Tap-to-Detect Electrochemical Biosensing and Chemical Sensing.

Printed electrochemical sensors offer a promising route toward decentralized diagnostics and environmental monitoring, but their practical use remains constrained by complex electrode fabrication and instrument-dependent readout. Here, we present a tap-to-detect sensing platform that couples digitally printed gold nanoparticle nanoelectronics with a battery-free near-field communication (NFC) potentiostat. Single-pass digital materials deposition enables direct fabrication of ready-to-use AuNP working/counter electrodes and AgNP reference electrodes on a flexible polyimide substrate, producing mechanically robust and electrochemically reliable devices. The NFC potentiostat provides smartphone-based wireless voltammetric readout with performance comparable to a commercial potentiostat. As proof of versatility, the printed AuNP electrode is applied to two distinct sensing modes: the thiol-mediated aptamer functionalization enables label-free HER2 biosensing with a detection limit of 4.87 pg mL-1 and successful analysis in spiked human serum, while the intrinsic Au-As interaction enables direct As(III) detection with a detection limit of 42.5 ng mL-1, without additional electrode modification. This digitally printed, smartphone-readable gold nanoelectronic platform provides a scalable pathway toward portable electrochemical sensing for healthcare and environmental applications.