This is the project that first got me interested in medical devices .My dad got a grant back in the early 70's to make a wristwatch blood pressure monitor .It used an arrangment of thin strain gages to detect the movment of a probe contacting the skin .It was hard to calabrate the pressure range because of the body movement but it did do a fair job of keeping track of the pulse rate .Although it never went to market it was a good experience in product development .I learned how to photo etch printed circuit boards and design circuits using op-amps and timers .brooks@robotgroup.org

http://www.robotgroup.net/brooks/transducer3.jpg