Design of Biomechanical Sensor System for Laboratory- and Field-based Measurements of Hand-Arm Vibration Exposures and Palm and Finger Forces

Hand-arm vibration syndrome (HAVS) is a disease commonly experienced by workers exposed to vibrating hand-held tools. A hand-held adapter approach to quantify vibration exposures at the palm of the hand is the most prevalent method recommended in the International Standards: ISO 10819 and ISO 5349. Due to the differences in the biodynamic responses of the palm and fingers, it is important to differentiate between palmar and finger exposure measurements, where the occurrence of HAVS may be more dominant. Grip and feed forces are influential factors of vibration exposure and the ability to reliably measure these forces may provide helpful insight on hand-tool coupling and exposure-response relationships, which are both crucial in designing effective prevention methods. Two biomechanical sensor systems, for laboratory- and field-based measurements, were developed in order to measure vibration exposures and grip forces at the palm and fingers during the exposure monitoring. The laboratory-based adapter system expands upon the adapter system in ISO 10819 by adding a finger adapter that allows for the evaluation of a glove attenuation effectiveness at the finger and, thus, assesses the overall vibration-reducing effectiveness of a glove more objectively. The field-based system expands upon the adapter system recommended in ISO 5349 with addition of a finger adapter that allows for differentiating between palmar and finger vibration exposures and reliably measuring palm and finger forces via force sensitive resistors (FSR). Both systems were manufactured using fused deposition modeling (FDM) 3D printing using polylactic acid (PLA) material and were thoroughly tested for vibration transmissibility to show that FDM 3D printing is a viable tool for manufacturing adapters for vibration exposure measurements.Palm and finger force measurements were verified using a cylindrical dynamometric handle and a force plate and showed that the field-adapter system is able to quantify grip force measurements with decent precision, especially in static dynamometric gripping. Glove transmissibility measurements showed significantly different results at the palm when compared to the finger, which was in agreement with previously published. Overall, both systems were able to accurately measure simulated tool vibration spectra and confirmed their viability in vibration exposure assessment