In one embodiment, a sensor includes a voltage driver operable to provide an alternating voltage and an integrator circuit. The sensor further includes a first variable resistance element coupled to a first output of the voltage driver and an input of the integrator circuit. The integrator circuit is operable to measure a parameter of the first variable resistance element over a period of time. The sensor further includes circuitry operable to determine, based on the measured parameter, an amount of force applied to a touch sensing panel.