Conventional static force - sensing mechanisms in e - skins mainly consist of resistive and capacitive sensing . Due to its simple mechanism and convenient data collection strategy , resistive pressure sensing has been extensively applied using various recording mechanisms . [ 111 ] Bulky piezoresistive e - skins , like sponge - based sensors , rely primarily on pressure - induced changes in the number of conductive pathways [ 112 ] or in the shape of the sensing material . [ 113 ] Meanwhile , other resistive sensors may analyze the changes in the contact resistance , like the quantum tunneling effect ( Figure 4A ) . [ 114,115 ] This type is much more sensitive and thinner than the bulky option . An e - skin based on bilayer microdome arrays can use microstructures to maximize the changes in surface contact resistance based on the tunneling effect ( Figure 4B ) . [ 115 ] Nevertheless , some drawbacks , like large hysteresis , [ 116 ] large confounding temperature sensitivity , [ 117 ] and varying pressure sensitivity [ 118 ] have limited the performance of resistive sensors . Compared with resistive sensors , capacitive sensors have excellent linearity with lower power consumption . [ 119 ] For piezocapacitive e - skins , capacitance changes are mainly based on the deformation of the dielectric layer . Normal pressure and tangential strain can be measured through a capacitive sensor as the dielectric layer can be deformed under tensile and external pressure ( Figure 4C ) . As demonstrated in Figure 4D , [ 120 ] a capacitive pressure sensing array with cross - arranged electrodes was fabricated using CNTs as the electrode material and PDMS as the dielectric layer .