Abstract: A processing apparatus is configured to receive a sense signal from a capacitive fluid sensor having a first electrode and a second electrode with a sensing region between the electrodes. The processing apparatus is configured to receive an alternating drive signal applied to the capacitive fluid sensor. The processing apparatus is configured to determine a complex impedance of the fluid sensor based on the sense signal and the drive signal. The complex impedance includes an in-phase component indicative of a conductivity quantity of a fluid in the sensing region and a quadrature component indicative of a capacitance quantity of the fluid sensor. The processing apparatus is configured to determine a temperature of the fluid in dependence on at least the determined capacitance quantity of the fluid sensor.

Abstract: Apparatus for measuring at least one property of a fluid comprises a capacitive fluid sensor (110) comprising a first electrode (111) and a second electrode (112) with a sensing region (113) between the electrodes. The apparatus comprises an alternating signal source (120) configured to apply an alternating drive signal to the capacitive fluid sensor (110). The apparatus comprises a processing apparatus (200) configured to receive a sense signal from the capacitive fluid sensor (110) and the alternating drive signal. The processing apparatus (200) is configured to: determine a complex difference signal comprising an in-phase difference component between the drive signal and the sense signal and a quadrature difference component between the drive signal and the sense signal; determine the at least one property of the fluid based on both the in-phase phase difference component and the quadrature difference component of the difference signal.