Fig. 2: The design method of conformal E-skin and mounting strain evaluation of units.

A The design method of hierarchical tactile force sensing units and integrated electrode based on 3D target surface. B The relationship between maximum mounting principal strain and mesh number with mesh levels. C The effect of surface topography and unit size on maximum principal strain. D The effect of material properties of E-skin and surface on maximum principal strain. E Comparison of non-modular design and modular design on the maximum and average principal strain. F Three-level unit layout for a rehabilitation ball. G Structural design of the tactile force sensing unit.