A MEMS piezoresistive resonator (8, 78) is driven at a higher order eigenmode (32) than the fundamental eigenmode (31). The route of flow of a sense current (22) is arranged in relation to a characteristic of the higher order eigenmode (32), for example by being at a point of maximum displacement (50) or at a point of maximum rate of change with respect to distance (x) of displacement of the higher order eigenmode (32). The route of flow of the sense current (22) may be arranged by fabricating the MEMS piezoresistive resonator (8, 78) with a trench (15) formed between two beams (11, 12) of the MEMS piezoresistive resonator (8, 78), the end of the trench being located at the above mentioned position.