V₂O₅ Thin Films for Flexible and High Sensitivity Transparent Temperature Sensor

This work reports the optimization of V₂O₅ Seebeck coefficient to obtain high sensitivity and transparent temperature sensors. It is observed that the film thickness plays a major role on the thermoelectric properties, together with the annealing step, obtaining a Seebeck coefficient of −690 μV K⁻¹, for 75 nm thick V₂O₅ films deposited on glass, after an annealing step of 1 h at 773 K, in air. The V₂O₅ films are also deposited and optimized on polyimide substrates, but lower annealing temperature is required, 573 K for 3 h, to maintain the flexibility of the substrate and simultaneously high Seebeck coefficient, −591 μV K⁻¹. These films are used in a simple design sensor and tested on the surface of a microfluidic channel (500 μm) made of polydimethylsiloxane, while having hot water flowing through it. The response time is below 1 s and the recovery time around 5 s.