Miniature ultrasonic imager for personal fitness tracking

A highly integrated low-power ultrasonic imager tracks changes of personal fitness by measuring the thickness of subcutaneous muscle and fat layers. The system combines a transducer fabricated from off-the-shelf PZT with a custom integrated circuit that implements all interface functions including high-voltage generation, beam forming, and and a low noise receiver for sensing and amplifying received echo. A novel transmit driver architecture is key to reducing the power dissipation of the high voltage circuits and enable battery operation. The system is capable of recording up to a depth of 6 cm in human tissue with 2mm depth resolution. Beam forming is used to improve signal strength and image quality in situations where the sensor and target are not parallel.