Development of 2D-graphene-based highly sensitive flexible strain sensor using fine columnar concentration structures

Aging society has become a serious social problem all over the world. Therefore, the researches in human-assisting robots' field has caused great attention. In order to provide highly reliable and safe services for human-robot interfaces, a highly sensitive and productive tactile sensor is strongly demanded. Our group designed a novel structure which used hard fine columnar structures to concentrate applied pressure and transfer it to graphene ribbon. The graphene ribbon was able to obtain much higher deformation under same pressure. Thus, it is possible to make a highly sensitive pressure sensor using column-graphene ribbon composite structure. The pressure sensor proposed in this paper consists of two sections: a concentration section and a detecting section. The concentration section was fabricated by hard PDMS film with periodically-aligned array contact structures on the surface, in order to concentrate and transfer the applied load to the detecting part. And for the detecting section, a flexible and deformable substrate was fabricated by using soft PDMS film on which graphene-ribbon (GR) was transferred. The force appears on the surface of the sensor was transferred and concentrated on the GR by the concentration section. And the change of the resistance of the locally deformed graphene-ribbon indicates the local pressure. Both of the two sections were fabricated independently as modularized products at first. And then, they were stacked together appropriately. At last, the performance of the fabricated pressure sensor was evaluated.