OPTIC FIBER AS A TRANSDUCER OF TENDOMUSCULAR FORCES

Direct in vivo tendon force measurements iii open up new possibilities for understanding of muscle-tendon loads during natural locomotion. T he present report presents a new optic fibre method for such applicati ons. The method is based on light intensity modulation by mechanical m odification of the geometric properties of the optic fibre. A special optic fibre with a plastic covering buffer and with a total diameter o f either 265 mu m or 500 mu m was carefully prepared at both ends for receiving and transmitting light. The fibre was inserted through the r abbit common calcaneal tendon with a 20 gauge needle. By removing the needle the optic fibre remained in situ. Static loading demonstrated t hat the voltage output of the optic fibre transducer showed a good lin ear fit of r=.999 with added loads. In dynamic loading conditions the optic fibre followed well the response of a strain gauge transducer, w hich was also attached to the tendon. The optic fibre method seems sui table for many applications for tensile and possibly ligament force me asurements.