Cardiac monitoring with novel low power sensors measuring upper thoracic electrostatic charge variation for long lasting wearable devices

Abstract

Cardiovascular disease is a major cause of premature mortality, high healthcare costs, and disability-adjusted life years. Digital interventions such as continuous cardiac monitoring solutions can help to monitor the patient status and provide valuable feedback to clinicians to detect early warning signs and provide effective interventions. This paper presents the evaluation of a novel low-power sensor exploited to measure the electrostatic charge variation in the upper thorax to provide an energy-efficient and accurate detection of the electric activity of the heart. The sensor is investigated for measuring the heart activity in terms of the QRS complex. The paper presents the design of a wearable sensor device, optimization of electrode positions and incorporation into a wearable chest strap that can be integrated seamlessly under clothes. Due to the low power consumption of the sensor, the sensor node consumes only 87.3 µW of power and can provide multiple weeks of operation using a coin cell battery while providing the same functionality as that of commercially available sensors such as photoplethysmography and electrocardiogram (ECG) ICs. In addition, the chest strap was also characterised for different use scenarios during sedentary and activity periods. We evaluated both the signal quality and the power consumption compared with other sensors technology showing a power save of an order of magnitude when compared with photoplethysmography sensors.