A field device comprising first and second tines; first and second rods coupled to the first and second tines; a coil arrangement fixed to the first rod; a magnet fixed to the second rod, opposite the coil arrangement; excitation circuitry coupled to the coil arrangement and controllable to provide a time-varying current to the coil arrangement, resulting in vibration of the first tine in relation to the second tine; sensing circuitry coupled to the coil arrangement and configured to provide a sensing signal indicative of a change in at least one property of the vibration of the first tine in relation to the second tine; and measurement control circuitry coupled to the excitation circuitry and the sensing circuitry for controlling operation of the excitation circuitry.