2, Korea Institute of Science and Technology (KIST), Seoul, , Korea (the Republic of)
In order to simulate body movements in the field of health care and soft robotics, studies on compliant stretchable strain sensors capable of converting mechanical strain into electrical signals have been actively investigated recently. In addition to sensing performance, there is a growing demand for the stability of sensors required for commercialization of compliant sensors such as linearity, hysteresis, and mechanical reliability. Capacitive strain sensor among various strain sensors is advantageous to obtain the stability of compliant strain sensor such as signal linearity and hysteresis aspects. However, application of capacitive strain sensors are still limited in that they could not have gauge factor more than 1 due to the isotropic deformation shape of incompressible dielectrics.
This study proposed a highly sensitive capacitive type strain sensor with robust mechanical reliability by using an elastomeric material having an anisotropic deformation shape. An appropriate two-dimensional mesoscale structural material was applied as a composite material to impart the strain anisotropy of the elastic dielectric. Through the architected design, highly stretchable capacitive-type strain sensor with an improved gauge factor of 3.21 was realized. In addition, the developed sensor could achieve 100 % stretchability, and excellent cyclic durability over 5,000 cycles under 30 % tensile strain with no mechanical degradation. Furthermore, our developed sensor maintained a large stiffness in the thickness direction that can suppress the deformation of the dielectric due to the pressure, thereby distinguished stretch signals clearly. Our research is advantageous in that it has developed materials with non-existed mechanical properties through architectural design of structural materials, and expected to open up a broader material table in the field of strain sensor engineering.