Soft and wet touch‐sensing system made of hydrogel

Abstract
Mechanical deformation of water‐swollen polyelectrolyte gels with carboxylic groups induces a spontaneous ionization, which in turn produces an electrical potential as large as a few millivolts. On the base of this phenomenon, a tactile sensor capable of lighting a photo diode array according to the amplitude of deformation has been made. This system may offer a soft and wet touch‐sensor due to its soft tissue‐like rheological characteristics.