A comparative study on the multidirectional piezo-resistive scenario of conventional and auxetic silicone-based sensors coated with graphite powder

The (comparative) study on the multidirectional piezo-resistive scenario of conventional and auxetic sensors is presented using silicone RTV2 as a base material coated with graphite powder as a sensing element. The key parameter of this comparison is the added area that appeared by applying the strain. The larger this parameter is, the larger the area for the sensing elements separation, and subsequently, the greater the sensitivity. To do the sensing performance test in a three-directional mode, a low-cost idea is to use a chuck lathe and an electric motor to open and close the chuck lath cyclically. The available commercial software ABAQUS2021 is used for numerical study. The sensitivity test on conventional and auxetic sensors in different loading modes shows that the performance of the auxetic sensor in unidirectional and bidirectional loading modes is 272% and 130% better than the conventional sensor, respectively. It means that if the added area for the two sensors is closer to each other, the sensory performance of the two sensors will be more similar. Although the sensing performance of the two sensors in the three-directional loading mode is almost equal, the consumed strain energy required to deform the conventional sensor is 30 times more than that of the auxetic one.