Force transducer for measurement of muscle contraction

Abstract

Single channel force transducers, intended for measurement and evaluation curves of preconditioned fibres in muscles contracting synergistically during direct or indirect electric stimulation of isolated muscle, were designed, developed and experimentally tested. The force transducers were made up of a full Wheatstone bridge composed of four semiconductor strain gauges bonded on a specially designed cantilever. The transducers with a natural frequency 350 Hz and compliance of 0.25 l mg^-1 represents a very linear dependence of the output voltage upon the load giving a sensitivity for the transducers of 0.5 mVmN^-1 with a bridge excitation voltage of 5 V. The nominal range of each transducer is 0-70 mN. The system is able to record even a contraction of only a few muscle fibres, both single twitches as well as sustained tonic contractions.