Simultaneous measurement of temperature and pressure using voltage-induced oscillation in vanadium-dioxide-based planar device

Abstract

Here we demonstrate simultaneous measurement of temperature and pressure by utilizing two waveform parameters of voltage-induced oscillation generated in a two-terminal planar device based on a vanadium dioxide (VO2) thin film for the first time. Two oscillation waveform parameters indicate the oscillation frequency fo and the oscillation amplitude Ao. To create the voltage-induced oscillation, a closed-loop circuit was formed by serially connecting a VO2-based two-terminal planar device, an external resistor, and a DC power supply that acts as a DC voltage source. Simultaneous measurement was done using three devices with different dimensions: Devices I, II, and III have current channel widths of 3, 5, and 10 μm with a fixed electrode separation of 10 μm, respectively. For Devices I, II, and III, temperature sensitivities of fo and Ao were measured as 17.27, 17.50, and 17.69 kHz/°C and −0.163, −0.156, and −0.160 V/°C in a temperature range of 25–50 °C without applied pressure (0 MPa) at 1 atm, respectively. Similarly, pressure sensitivities of fo and Ao were measured as 58.15, 58.48, and 59.08 kHz/MPa and −0.471, −0.451, −0.450 V/MPa for Devices I, II, and III, respectively, in an applied pressure range of 0–5 MPa at room temperature (25 °C). Owing to their linear and independent responses to temperature and pressure, temperature and pressure changes applied to the VO2 device could be found out using the above premeasured temperature and pressure sensitivities of fo and Ao.