Abstract: A transducer is described for simultaneously measuring several parameters of a small region of a muscle tissue or other object, with minimal traumatizing or damage of the object. A trifunctional transducer which can measure the force applied by a muscle fiber, the displacement of the fiber, and the change in thickness of the fiber, includes a device having three legs with inner ends joined together and outer ends formed to pierce the tissue and lie therein. Two of the legs are relatively stiff, to measure force applied by the tissue, and a third leg is relatively flexible to measure displacement of the tissue relative to one or both stiff legs, and with the three legs lying in a common plane so that the force and displacement measurements all relate to the same direction of muscle movement.