Fabrication and structural characterization of motion sensors. (a) The fabrication process of the motion sensor. (b) Optical images of PU blocks and MXene-coated PU blocks. Inset is an SEM image for MXene-coated PU blocks. (c, d) The SEM image of the slit sensilla of the scorpion. (e) The SEM image of the lateral wall of the blocks. (f) The SEM image of MXene-coated keel structures, showing the uniform distribution and tight interfacial contacts between MXene and PU keel structures. (g) Corresponding energy-dispersive X-ray spectroscopy (EDS) mapping of C, Ti, and O in the MXene-coated PU keel structures. (h) A tight interfacial contact is formed between the PVA gel and the MXene-coated PU blocks. The inset shows the details of the tight interfacial contact.