The problem of poor signal quality of biometric measurement is improved with a new headset construction. The new headset includes a sensor assembly that provides more stable and secure contact between the sensor electrodes and the scalp of the wearer of the headset. The sensor assembly includes a housing unit for the electrodes and has a flexible and collapsible wall portion, which flexes and deforms according to the strength and the location of the pressure applied to the electrodes to maximize the contact area between the scalp and the sensors.
