Miniature photoelectric 3D force sensor with integrated LED-PD transceivers

This Letter presents a novel, to the best of our knowledge, miniature three-dimensional (3D) force sensor featuring integrated light emitting diode (LED)-photodiode (PD) transceivers to achieve the detection of the amplitude and tilt angle of the 3D force. It senses the change of the reflected light path of the photoelectric transceivers caused by the displacement of elastomers under force, based on the photoelectric principle. In order to reduce volume and improve performance, the LED-PD transceivers are designed and monolithically fabricated by utilizing the technique of multiple quantum well structures. The characteristics of the photoelectric transceivers are tested, with the overlapping wavelength of 439.75-483.97 nm between the LED emission spectrum and the PD detection spectrum. The experiment demonstrates that this 3D force sensor has the ability to measure forces of 0-6 N and tilt angles of up to 3.9°, where good linear relationships of output response are obtained. The measured repeatability error and hysteresis error are less than 3.46% and 3.41% for the tilt angle, and 3.13% and 3.13% for the amplitude of the 3D force, respectively, due to the collaborative design of the transceivers and elastomers.