Smart wireless headphone for cardiovascular and stress monitoring

Wearable technology has become ubiquitous in recent years due to the miniaturization of circuit electronics and advances in smart materials that can conform to the requirements posed by the human body, behaviour and experience. Sensors of this type are found attached almost to every body segment, capable of delivering signals even in harsh activity scenarios. The reliability and relevance of the physiological data retrieved by wearables have yet to surpass the conventional technologies in the healthcare system today. In this paper we present a small device incorporated inside an headphone set that continuously monitors the ECG, impedance and acceleration of the head. As opposed to most biometric sensors, ECG measurement relies on non-optical methods by capturing the electrical potential around the ear in both sides of the head, whereas impedance monitoring involves AC stimulation instead of DC, the latter commonly involved in skin galvanic response estimation. Signal processing of impedance parameters is performed in situ using a fast variant of the Discrete Fourier Transform in order to save computational resources and power expenditure from a microcontroller equipped with Bluetooth Low Energy. Applications that can benefit from this device include cardiovascular and stress level assessment of individuals for whom an hearable is a requirement for work or leisure.