Wearable e

Two key heart measurements for a comprehensive picture of heart health

The e-tattoo device measures two crucial aspects of the heart: the electrocardiogram (ECG) and seismocardiogram (SCG). The former gauges the heart's electrical signal, while the latter assesses the acoustic signal from the heart valves. Although ECG can be measured using mobile devices like the Apple Watch, and SCG can be monitored using a stethoscope, there's currently no mobile option that approximates a stethoscope or obtains both measurements. By integrating both measurements, a more comprehensive and complete heart profile is possible, enabling the measurement of cardiac time intervals, which is a significant indicator of heart disease and other issues.

Five healthy patients were tested with the device in their daily surroundings, exhibiting a low rate of errors in comparison to existing monitoring alternatives. The next phase involves additional testing and confirmation of the initial outcomes, along with expansion to a diverse patient population. 

The device was created as part of a partnership among multiple universities, which was granted funding in 2021 from the National Science Foundation's ASCENT initiative to explore chest e-tattoo technology.

Implications for preventing heart disease

The United States' top cause of death is heart disease, but a new e-tattoo has the potential to significantly aid in combating this issue. It allows for uninterrupted and portable heart monitoring beyond the confines of a medical facility, aiding in the early detection of heart disease warning signs and facilitating prompt diagnosis and treatment.

According to Nanshu Lu, a professor in the Department of Aerospace and Engineering Mechanics and a lead author of the study, "If that can be done, 80% of heart disease can be prevented." The e-tattoo's non-invasive monitoring and comprehensive measurements could help clinicians gain a better understanding of heart health and potentially prevent heart disease.

The study has been published in Advanced Electronic Materials.

Study Abstract:

Cardiovascular diseases are the leading cause of death globally. Noninvasive, accurate, and continuous cardiovascular monitoring can enable the preemptive detection of heart diseases and timely intervention to prevent serious cardiac complications. However, unobtrusive, ambulatory, and comprehensive cardiac monitoring is still a challenge as conventional electronics are rigid, heavy, or consume too much power for long-term measurement. This work presents a thin (200 µm), stretchable (20%), lightweight (2.5 g), wireless, and low-power (<3 mW) cardiac monitoring device that conforms to the human chest like a temporary tattoo sticker, correspondingly known as an e-tattoo. This chest e-tattoo features dual-mode electro-mechanical sensing—bio-electric cardiac signals via electrocardiography and mechanical cardiac rhythm via seismocardiography. A unique peripheral synchronization strategy between the two sensors enables the measurement of systolic time intervals like the pre-ejection period and the left ventricular ejection time with high accuracy (error = −0.44 ± 8.74 ms) while consuming very low power. The e-tattoo is validated against clinically approved gold-standard instruments on five human subjects. The good wearability and low power consumption of this e-tattoo permit 24-h continuous ambulatory monitoring.