Silicone embedded FBG sensor for quantitative finger tapping assessment: A feasibility study

• The proposed FBG sensor offers non-invasive, touchpad-like sensing solution. • The circular geometry exhibits an improved sensitivity of 17.8pm/N. • The sensor design is universal and accommodates fingers of varying sizes. • The sensor shows potential for quantitative finger tapping assessment The finger tapping test is a widely used clinical assessment tool that involves analysing finger tapping movements under specific conditions for a set duration. It is particularly useful for diagnosing neurological disorders that affect motor control and coordination. Conventional finger tapping tests are often qualitative and rely on visual observations, with measurements taken using systems that are bulky, complex, and not user-friendly. As an alternative, this study presents a touch pad-like solution using a compact Fiber Bragg grating-based finger tapping sensor embedded in a custom-designed circular silicone patch. The embedding design enhances flexibility, durability, and portability. Furthermore, the proposed sensor design closely matches the natural shape of the fingertip, improving user comfort along with a universal design. The proposed sensor exhibits a force sensitivity of 17.8 pm/N with a consistent response. To evaluate the sensor's practical performance, five healthy volunteers performed two different types of tapping tasks, fast and rhythmic, using their dominant and non-dominant hands. The sensor efficiently detected wavelength shifts corresponding to each individual’s tap. A comparative analysis of tap force measurements, along with the measured average inter-tap interval, suggests individual tapping patterns, as well as the impact of hand dominance and task type. The results demonstrate that the sensor's effectiveness in real-time monitoring of motor performance may aid in objective clinical evaluation.