C@VO2 nanocoils for micro/nanoscale self-powered dual-functional thermal and photoelectric detection.

As the size of transistors shrinks and integration density increases, micro/nanoscale thermal management becomes crucial, triggering the development of a micro thermoelectric probe. Carbon nanocoils (CNCs) possess excellent flexibility and mechanical stability, but their low Seebeck coefficient severely restricts thermoelectric detection performance. Vanadium dioxide (VO2) shows outstanding phase-transition behavior and high thermoelectric response, yet is difficult to apply in flexible micro/nano thermal probes. In this work, a self-powered microthermal detector based on C@VO2 nanocoils (CVNCs) was proposed. The composite structure preserves the intrinsic electrical transport and insulator-metal transition of VO2, with carrier transport transitions around 170 and 340 K. Its Seebeck coefficient decreases from 121 to 6 µV K-1 from 30 to 65 °C. A single CVNC realizes micro/nano optical positioning, and CVNC-CNC thermocouples achieve linear temperature and photo-thermo-electric dual-functional detection with a high signal-to-noise ratio. Our study provides a feasible design strategy and a core unit for micro/nanoscale thermal characterization.