Phonocardiography, photoplethysmography with simple Arduino setups to support interdisciplinary STEM education

We show several ways how heart function can be monitored by studying photoplethysmograph and phonocardiograph signals with very simple Arduino-based setups in high-school or university education. We have carefully analyzed and demonstrated the problems of widely used solutions and we show the technically correct ways which are surprisingly rare and particularly important in high quality STEM education.<br>