Researchers from Wayne State University have developed a new, highly sensitive wearable sensor designed to monitor patients with cardiac problems and can even detect early COVID-19 symptoms. The tiny sensor is based on two forms of ionic forms of reversible iodine (I- and 13-) solution, which is placed within a 3D-printed cavity using a thin, flexible diaphragm that can detect minute movements on the wearer's chest.
Those subtle movements, produced by heartbeats and breathing, cause that flexible diaphragm to move, pushing the iodine fluid into a chamber, where it's electrochemically detected by four platinum-plated electrodes. The team created the cavity using a mold for the circular chamber, then filled it with EcoFlex — a resilient, flexible silicon rubber commonly used in orthotics and prosthetics. After forming the sensor's body with EcoFlex, the sensor was spin-coated on a rapidly spinning disk to form the thin diaphragm.
After the chamber and diaphragm are bonded together, the researchers then used a syringe to fill the cavity with the iodine solution. The completed sensor measures-out at only 28mm wide and is skin-safe so that it can be attached directly to the patient's body. Respiration can be detected using two methods — as a strain sensor, measuring the diaphragm's deformation during breathing, and changes to chest volume during breathing, which modulates the heartbeat signal. The latter is based on changes in the patient's heartbeat via normal breathing. The sensor is capable of detecting a heartbeat with high sensitivity and boasts a signal-to-noise ratio of 6:1, which is considered outstanding.