Improvement of Electrical Heating Wire Structure of Force Sensors Using Shape-Memory Polymer

We previously developed a variable-sensitivity force sensor that uses a cantilever made of a shape-memory polymer (SMP) sheet with an embedded electrical heating wire, the stiffness of which varies according to temperature. In this study, we improve the structure of the heating wire using computer numerical control machining. Furthermore, we fabricate an SMP force sensor with a beam fixed at both ends. Experiments using prototypes of the original and improved sensors demonstrate that the temperature distribution of the heated SMP sheet and the distance between the electrical heating wires are uniform. Moreover, we confirm that for both prototype sensors, the relationship between strain and force depends on temperature.