A Foot Sampled Pulse Sensor for Bathroom Scale Application

A smart bathroom scale is presented in the paper. It is a classical bathroom scale enriched with the possibility of measuring a reflective photoplethysmographic (PPG) signal. To achieve such functionality an optical reflective transducer was developed. Its location in the scale platform was selected according to the anatomical structure of the foot and the typical procedure of weight measurement when using the scale. An electronic circuit for the sensor was designed and developed. Its performance was examined and compared with the commercial system. However, in the latter system, a plethysmographic signal was measured on the hand finger. This signal was utilized as an accurate timing synchronization one. Finally, we have shown preliminary results obtained due to performing measurements on a small group of healthy volunteers. Additionally, an algorithm for pulse rate estimation that could apply to such, relatively low-quality data was proposed.