Wireless Battery-Free Generation of Electric Fields on One-Dimensional Asymmetric Au/ZnO Nanorods for Enhanced Raman Sensing.

Abstract

Wearable electronics have great potential in enhancing health monitoring, disease diagnosis, and environmental pollution tracking. Development of wearable surface-enhanced Raman spectroscopy (SERS) substrates with target sampling and sensitive sensing functions is a promising way to obtain physical and chemical information. This study describes a facile and effective approach for constructing an electrically modulated SERS (E-SERS) substrate as a wearable and wireless battery-free substrate with improved sensitivity. By integrating zinc oxide nanorods (ZnO NRs) with asymmetric gold decoration, controllable enhanced piezoelectric potentials were achieved using magnets to supply the adjustable pressure force. Owing to spatially oriented electron-hole pair separation on the asymmetric NRs, the local hotspot intensity at the Au tips is significantly improved, increasing the SERS signal by 6.7 times. This mechanism was quantitatively analyzed using Raman spectra by in situ formation of Prussian blue (PB). As a proof-of-concept, the E-SERS substrate was further used as a wearable flexible device to directly collect the sweat on a runner's skin and then monitor the lactate status of the runner. This study offers new insight into the development of E-SERS substrates and provides new design options for the construction of wearable sampling and sensing devices for the noninvasive monitoring of metabolites in healthcare and biomedical fields.