Molecular Fingerprint Detection Using Portable Water-Compatible Electronic Tunneling Spectroscopy Device

Real-time and label-free recognition of molecules is highly desired in numerous fields; however, most existing detection schemes require specific functionalization of the device suited for the molecule to be detected and is often complicated by nonselective adsorption. Current detection methodologies that deliver detailed molecular-level information typically require elaborate analytical instrumentation to overcome these limitations, rendering those costly, not scalable, and nonportable techniques. Herein, a detection scheme is presented that rely on measurement of the tunneling currents through molecules under ambient conditions by employing a robust, scalable, portable, and water-compatible device. High aspect ratio semiconductor–metal hybrid nanosystems, which feature a metal tip (Au) that functions as a nanoelectrode, are utilized to create self-formed nanojunctions. Analyte molecules intercalate between the nanoscopic gold tip and a counter electrode, resulting in distinctive tunneling currents. Characteristic dI/dV fingerprint traces, unique to the density of states of the molecular species embedded in the liquid medium, are detectable. Resetting is demonstrated by desorption of adsorbed molecules by applying a reset voltage bias. This study paves the way toward low-cost, on-site, and real-time information-rich molecular detectors.