Performance Verification of Highly Stretchable Soft Sensors

Abstract

Soft sensors have attracted much attention due to its inherent characteristics such as stretchability and softness. However, stretchability of the soft sensor might be limited by the mechanical properties of silicone material, elongation break, shore hardness, tensile strength, and so on. In this study, we validate the effect of the material on the sensor performance, comparing silicone materials with different mechanical properties. Pull-to-failure tests and cyclic loading tests were conducted to validate sensor performance in terms of stretchability, sensitivity, and durability. For the experiments, soft sensors were made by three different materials (Ecoflex 0030, Dragon Skin 30 and Material A) through a direct ink writing (DIW) method. In experimental results, a soft sensor made by Ecoflex 0030, which had large stretchability, was easily broken by local external pressure because of its extremely low hardness. Also, a soft sensor made of Dragon Skin 30 had strain range less than 100 % due to the limited elongation at break and high stiffness. The soft sensor made by Material A with high elongation at break, low stiffness, and moderate hardness had 300 % strain range with gauge factor of 5.7 which is twice larger than the other sensors.