[6p-C11-1~14] 12.3 Functional Materials and Novel Devices

△ [6p-C11-4] Development of conductive polymer-based ultrathin epidermal strain sensor

〇(M2)Yuma Tetsu¹, Kento Yamagisi¹, Akira Kato², Yo Kobayashi^3,4, Shigeki Sugano², Shinji Takeoka¹, Toshinori Fujie^4,5 (1.Grad. Sch. of Adv. Sci. & Eng., Waseda Univ., 2.Grad. Sch. of Cre. Sci. & Eng., Waseda Univ., 3.Future Robotics Organization, 4.JST PRESTO, 5.WIAS, Waseda Univ.)

Keywords:Strain sensor, Polymer nanosheet, Conductive polymer

In recent years, the soft robots featuring "softness" composed of soft materials such as organic molecules, etc. has been developed for conventional robots made of hard materials such as metals. In order to mimic the softness inherent to a living organism, it is necessary to accurately grasp minute deformation of living tissue. However, with the conventional strain sensor, it is difficult to measure minute deformation of flexible living tissue such as skin due to the rigidity of the material itself. A polymer ultrathin film (nanosheet) has large contact areas (>cm²) with respect to a film thickness of several hundreds of nm, and shows superior followability to living tissue, so nanosheets are suitable materials for a sensor for measuring soft tissue deformation. In view of this, the nanosheet inkjet-printed a conductive line on the surface is expected to be applied as a strain sensor that changes the resistance value according to the extension and contraction of the skin while following the fine irregularities of the epidermal structure. In this report, we aimed to develop a strain sensor able to measure fine deformation of skin only by pasting.The nanosheet was made from elastomer (polystyrene-block-polybutadiene-block-polystyrene: SBS) by roll-to-roll process(thickness: 321 nm), on which a conducting polymer poly (3,4- ethylenedioxythiophene): poly (styrenesulfonate ) (PEDOT: PSS) was inkjet-printed to produce a nanosheet strain sensor (line width 1 mm, length 5 cm, wiring resistance 2.40 kΩ) (total film thickness <1 μm, Young’s Modulus 227 ± 32 MPa). When the change in the resistance value to the uniaxial strain was measured by the tensile test (Strain Speed: 1 mm / min), the gage factor was calculated to be 0.73 ± 0.10. Moreover, the nanosheet strain sensor was shown to respond with good reproducibility for the repetitive strain of 0-2%. Furthermore, when the strain sensor was attached to the human forearm and the wrist was bent and stretched, it was shown that the resistance value changes in response to minute deformation of the skin. Based on the above, the nanosheet strain sensor is expected to be applied as a strain sensor capable of measuring minute skin deformation accompanying human motion and facial expression change.