Development of a small wireless position and bleeding detection sensor

Medical capsule devices such as video capsule endoscopes are finding increasing use in clinical applications. At present, technologies capable of measuring capsule position and detecting a bleeding in the digestive tract at the same time have not yet been established. The present study aims to develop a small wireless position and bleeding detection sensor. The sensor position are measured by using the phenomenon of mutual induction and Newton´s law. Electromotive forces induced in the sensor are modulated to FM signals using an astable multivibrator, and the signals are passed directly through living tissue at low current and then demodulated by detectors on the surface of the body. A prototype sensor was developed and evaluated in vitro. The sensor was capable of accurately measuring capsule position up to 500 (mm) from the primary coils with an accuracy of 5 (mm), and detecting 0.5 cc blood in 500 cc physiological saline.