Drexel’s electrical engineers have developed a wearable, wireless and battery-free continuous health monitor that can be used in a wide range of applications. The core of the monitor is an off-the-shelf RFID tag connected to a proprietary circuit. The circuit registers electric signals of the body and converts them into heart rate information that is then transmitted by the RFID. In a battery-free mode the monitor is powered by an energy harvester, which converts electromagnetic energy surrounding us in daily life (Wi-Fi, cellular networks etc.) into electricity. The monitor’s signal can be read by a standard RFID reader located 10-15 feet away from a battery-free version, or a much greater distance if the monitor is powered by a small coin battery. The RFID tag is used as an on-off keying device to measure the heart rate, and the tag’s returned signal strength variations, caused by body’s movements resulting from breathing, are used to calculate the respiration rate. RFID signals are processed using machine learning algorithms to determine the health parameters.

For seamless integration in garments, the heart rate electrodes and major energy harvester parts can be knitted during garment’s manufacturing using specialized conductive fibers, thus minimizing the hardware footprint of the monitor. These technologies have also been developed by the inventors and their collaborators at Drexel.