Finger Force Sensor Instrumentation Design

Carpal tunnel syndrome (CTS) refers to a class of injuries characterized by compression of the median nerve in the carpal tunnel. CTS injuries cause pain, weakness, and numbness in the hands and are common among video gamers and workers that maintain their wrists in ergonomically unfavorable positions. Current CTS qualification methods are well documented, whereas the condition of the hand muscles is often overlooked. At present, there is no simple, inexpensive, and portable instrument that quantifies finger force values pre and post clinical intervention. Our design measures finger force using force sensors placed on the surface of individual keys on an ergonomically designed keyboard, which allows finger force measurements for all five fingers, individually or as a group. In this work we; 1) Show a clear difference in finger force between an uninjured and injured hand and further correlated it to forearm electromyography (EMG), and 2) Use the system in a pilot study to evaluate the apparatus usefulness through the testing of the significance of finger force before and after fatigue. Finger force signals from the subjects' index finger were collected and force peaks extracted from the raw data. The resulting data was analyzed using the variance (ANOVA) test. Although, there was no statistical significance between the finger force applied, the system proved accurate, rugged, and flexible to accommodate fine tuning changes on hardware and software, with a minimum of dead time during the pilot study. Thus, this tool offers a great platform for further finger force studies.