Apparatus for sensing and indicating vaginal muscle contraction

Vaginal muscle contraction is sensed by change of pressure within a flexible, hollow tubular member that is adapted to be compressed in response to muscle contraction. A simple pressure transducer embodies a pressure tube connected with the tubular sensing member and having an end covered by a flexible diaphragm that expands in response to increased pressure so as to progressively block light transmitted to a photosensitive resistor. The resistor controls an electrical signal that is employed to provide an audible or visual display that provides a measure of relative strength of muscular contraction and which also may be used in a biofeedback loop to inform the user of the intensity of the contraction. Accuracy of the inexpensive transducer is increased by compensating the output electrical signal for both nonlinearity and hysteresis of the distensible rubber diaphragm.