Pre-bent U-shaped optical microfiber embedded in multilayer PDMS film for large-scale bending measurement

We propose a sensing film for large-scale bending measurements. Bi-conical microfiber was prepared using standard single-mode fiber and placed into pre-bent U-shape embedded with multilayer PDMS (polydimethylsiloxane) film, in which the effect of different ratios on the properties of PDMS was exploited. The shape of the microfiber placed and the structure of multilayer PDMS make the sensing film more responsive to bending, allowing for a wide range of bending angle measurements. And the ability to withstand a large degree of bending and stretching simultaneously enables the application of real-time monitoring and identification of knuckles and other joints. By analyzing the relationship between the output voltage and the bending angle, it successfully distinguished finger movements at different bending angles. In addition, the repeatability and stability of the sensing film were also proved to be excellent. It can be applied in many related fields such as human–computer interaction control, human health monitoring, clinical diagnosis of movement disorders and rehabilitation training.