Determining the minimum number of thin-film force sensors required to represent actual hand grip forces

In this study, the minimal number of sensors needed to measure grip force using thin-film point force sensors is explored. Thin-film sensors were used in conjunction with a strain-gauge instrumented cylindrical handle allowing for the simultaneous measurements of localized point measurements and overall grip force. Analysis of the relationship between the sensors and the handle allowed for the determination of the minimum number thin-film sensors needed to accurately represent the overall grip force behavior. Although 32 locations were studied on four subjects of varying gender and hand size, only the data from sensor placements on the pads of the distal phalanges and the palmar aspect of the metacarpophalangeal joints are presented. For these sensor locations, results suggest that four thin-film force sensors can adequately represent the overall grip force with significant accuracy. Minimizing the number of thin-film force sensors used to accurately represent the total grip force behavior is necessary in order to limit sensor bulk in field instrumentation systems that incorporate grip force measures, such as those used to study musculoskeletal disorders like Hand-Arm Vibration Syndrome (HAVS).