Reflectocardiography (RCG): A leadless, optical reflection based facile measurement of human cardiac rhythm

Cardiac diseases have been one of the leading causes of death in developed and developing countries. This can be attributed to the prevailing eating habits as well as unhealthy work–life balance and lifestyle. There have been many instances where scientists, researchers, and innovators working in the domains of engineering, biotechnology, and healthcare have proposed novel ways to monitor the cardiac activity of a diseased person. Such monitoring systems started with the advent of electrocardiography followed by other methods, such as echocardiography, phonocardiography, and photoplethysmography, which led to better patient care. Recently, there has been growing interest to monitor the cardiac activity by mechanical movements of the body parts/surfaces, which has led to the beginning of new fields, such as gyrocardiography, ballistocardiography, seismocardiography, and forcecardiography. All these mechanical sensors have very sophisticated components attached to them, thus making them relatively less available in low-cost settings. In this work, we propose a proof-of-concept to optically measure the seismic thumps due to the heartbeats by keeping a reflecting surface over the epigastric region of the abdominopelvic cavity. Due to these thumps, the reflecting surface moved vertically and the position of the image of an otherwise stationary object in the reflecting surface was monitored using a camera. This mechanism is an inexpensive alternative to replace the costly MEMS components that constitute mechanical cardiograms and would reduce the cost of measurements substantially. It would be of great interest to scientists and healthcare researchers to explore the viable alternatives to low-cost settings.