A Low-Cost Non-Invasive Continuous Cardiovascular Monitoring System Based on Oil-Filled Rubber Tubing

Cardiovascular monitoring at home is highly desirable for managing diseases such as heart failure. Existing technologies are either inconvenient, too costly, or incapable of acquiring clinically valuable information. We developed a new low-cost and sensitive monitoring system based on rubber tubing, mineral oil, and an off-the-shelf pressure sensor. The rubber tube can be installed underneath bed mattresses and chair cushions to convert the ballistocardiogram (BCG) signal caused by heartbeat to pressure change, which is then detected by the pressure sensor. The sensitivity is increased by filling the tube with mineral oil based on Boyle's gas law (PV = Constant). Preliminary tests demonstrated that the new monitoring system can record BCG with high sensitivity from the bed. From the recorded signal, both heart rate and respiration rate can be extracted. Other valuable information such as myocardial strength and respiration strength can be potentially derived as well. The new monitoring system is low-cost, sensitive, robust, unattended, and does not need to attach any device to the patient. This new monitoring system will be beneficial for the monitoring of health conditions such as heart failure, sleep apnea, epilepsy, and respiratory diseases such as COVID-19.