A Star Is Worn

Wearable electronic devices do an admirable job of collecting physiological data from their wearers, but we certainly do not make it easy on them. We spend our days moving, exercising, sweating, showering, and doing all sorts of other activities that put our wearable devices through the wringer. All of this makes it difficult for them to consistently capture accurate data, and that means we cannot always rely on the data they produce — at least not in critical applications, like health monitoring, where total accuracy is absolutely essential.

A new wearable bioelectronic system developed by a team led by researchers at the University of Missouri may be able to brush off the challenges posed by our active lifestyles. Their system — as is so often the case with experimental technologies in this area — was inspired by nature. The team borrowed from the starfish’s pentaradial structure to create a novel system that remains stable even during movement. They then applied this technology in creating a more reliable wearable heart monitor.

Traditional wearables, such as smartwatches, struggle to maintain consistent contact with the skin during movement, leading to inaccurate or incomplete data collection. The new starfish-inspired device solves this by using five flexible arms, each equipped with sensors that make multiple points of contact with the skin near the heart. These independent sensing elements work together to mitigate movement-induced signal disruptions, providing clearer data.

The device simultaneously captures three types of cardiac signals that describe its electrical and mechanical activities. Through electrocardiography (ECG), it measures the heart's electrical activity. Seismocardiography makes it possible to track vibrations caused by heartbeats, and gyrocardiography is used to monitor rotational movements of the chest that arise due to cardiac activity.

Each of the five arms is equipped with a BMI270 accelerometer-gyroscope unit, a high-performance motion sensor that helps differentiate actual heart activity from movement artifacts. Additionally, gold-plated copper electrodes are integrated into the sensing pads to record ECG signals.

A 32-bit microcontroller at the center processes the signals in real-time, while Bluetooth connectivity enables wireless data transmission to a paired smartphone. This data can then be sent to the wearer’s physician for diagnostic purposes. The system also incorporates machine learning algorithms into its design, which analyze the heart signals to detect abnormalities such as atrial fibrillation, myocardial infarction, and heart failure with an accuracy exceeding 91%.

To avoid downtime — and the associated gaps in data collection — the system was given a wireless charging capability. An onboard rechargeable LIR1240 battery (50 mAh) allows for about eight hours of continuous use, after which wireless charging coils can top it off. This arrangement allows the device to be recharged at any time, and under nearly any conditions, even underwater.

As currently designed, the device sticks to the skin via special gels. A nonconductive biogel adheres the central hub to the skin, while a conductive gel is applied to the ECG sensing pads. These gels may be uncomfortable for prolonged use, so the team is developing a breathable, skin-friendly material as a replacement. That would go a long way toward enhancing the device’s long-term wearability.

Though still in the early development stages, this wearable system holds a lot of promise for precision healthcare, telemedicine, and even applications beyond heart monitoring in the future, such as human-machine interfaces and augmented reality.