Fig. 4: The sensing demonstrations of the multisensory tactile sensors during the softness recognition procedure.

a Measured relative resistance change of LM sensors integrated in the proximal and distal finger ends of a manipulator. b Optical images of the manipulator movement in the process of identifying the softness of the sponge. c The voltage output of the flexible piezoelectric layer as a function of time while the manipulator touches the sponge.