Biomimetic Liquid Metal Elastomer Foam With Stress Sensing

Liquid metal elastomer (LME) has a high permittivity due to the equipotentiality of liquid metal (LM) particles. Introducing a porous structure prepares LME foam (LMEF) with piezopermittivity, which has a high stress sensitivity as a stress sensor. However, the random porous structure of LMEF limits the piezopermittivity and the improvement of sensitivity. To solve this problem, a biomimetic LMEF (BLMEF) inspired by the lotus seeds is introduced, which has high porosity (
$>$
70%) and large permittivity variation (
$\approx 5.6$
). Mechanical and dielectric properties are investigated through the finite-element analysis and experiments. A flexible capacitive stress sensor is fabricated based on BLMEF. The BLMEF-based stress sensor has high stress sensitivity (2.59 kPa
$^{-{1}}{)}$
and high stability. The sensor can measure human motions, demonstrating potential applications in the field of human motion monitoring. In addition, a smart ergonomic cushion is demonstrated.