A surgical instrument assembly can comprise a handle including an electric motor, a shaft assembly including a drive member, and a magnet configured to generate a magnetic field. The surgical instrument assembly further comprises, one, a rotatable output shaft operably coupled with the electric motor and the drive member and, two, a wire coil wound around the output shaft which is positioned in the magnetic field. The wire coil is rotated within the magnetic field when the output shaft is rotated about a longitudinal axis which induces a current in the wire coil. The surgical instrument assembly further comprises a strain gauge mounted to the output shaft configured to detect strain created within the output shaft and, in addition, a circuit mounted to the output shaft, wherein the circuit and/or the strain gauge is powered by the current induced in the wire coil.
