Polymer optical fiber sensors approaches for insole instrumentation

Advantages like electromagnetic field immunity, fracture toughness, high strain limits, flexibility in bending and impact resistance of polymer optical fibers (POFs) are beneficial for applications that involve embedment in flexible structures. Since insoles are one of these flexible structures that may be used in different wearable applications, POFs can be applied and this paper proposes the application of POF sensors in insole instrumentation with two different approaches: intensity variation-based and polymer optical fiber Bragg gratings (POFBGs). Results show that both approaches present low errors with root mean squared errors (RMSEs) of 45.17 kPa for the plantar pressure monitoring with the POFBG-based insole and 5.30 N for the ground reaction force measurement with the intensity variation sensors. These results demonstrate the feasibility of POF sensors applications in flexible structures and in wearable applications such as insoles and soft robotics instrumentation.