A wrist worn device includes a metal device housing and a capacitive touch sensor. The capacitive touch sensor includes a conductive plate which is supported by and separated from the metal body of the device housing via an isolation body formed of PTFE (low static relative permittivity). An outer plate is formed over the conductive plate and is formed of glass (high static relative permittivity). The action of the isolation body is to reduce the effect of the metal device housing on the capacitance detected by the conductive plate. The effect of the outer plate is to try to increase the effect of the capacitance associated with the object being brought into proximity with the conductive plate.