Abstract: A sensor device for measuring frequency and amplitude of a varying force signal is provided. The sensor device comprises a sensing element defined by a plurality of even numbered planar segments symmetrically disposed about a central axis, a protective housing for housing, an interface element comprising a pick up member, a planar mechanical actuator, a transfer member adapted to receive varying signals from the pick up, amplify the signals picked up and transfer the amplified signals to the said mechanical actuator; and leads for transmitting said output signals outside the sensing device for processing.