Warning: This application note illustrates the use of the strain gauge in the construction of a hand dynamometer. It is not intended for actual medical use.
A hand dynamometer is used to measure grip strength. The measurement of grip strength allows for comparison of left and right hand grip and muscle fatigue. Muscle fatigue can be measured by comparing the difference in hand strength measurements taken before and after an experiment has been performed. In sports, hand grip strength is important for those games where the hands are used for catching, throwing or lifting. In geriatric, one study found that poor hand strength can be used to predict disability in older people1.
Our simple hand dynamometer is made by attaching a strain gauge to an easily available Hand Exercise Grip. Together with the EMANT300 USB DAQ and the strain application adaptor, the strain gauge is connected in a quarter bridge configuration. We used the strain example program in either LabVIEW or C# to measure the strain.
Below is part of the C# program that reads the voltage across the bridge and converts the voltage to μstrain. We use software zeroing of the offset.