The latest version of the team's electronic tattoo technology, the ultrathin lightweight and stretchable device can be placed over the heart for extended periods with little or no discomfort. Powered remotely by a smartphone, the e-tattoo measures cardiac health in two ways, taking electrocardiograph and seismocardiograph – a measurement technique using chest vibrations associated with heartbeats – readings simultaneously.
According to the researchers, their e-tattoo is the first ultrathin and stretchable technology to measure both ECG and SCG.
"We can get much greater insight into heart health by the synchronous collection of data from both sources," says Nanshu Lu, an associate professor in the departments of Aerospace Engineering and Engineering Mechanics and Biomedical Engineering.
Although soft e-tattoos for ECG sensing are not new, says Lu, other sensors, such as the SCG sensor, are still made from nonstretchable materials, making them bulky and uncomfortable to wear. The new e-tattoo is made of a piezoelectric polymer called polyvinylidene fluoride, capable of generating its own electric charge in response to mechanical stress. It also includes 3D digital image correlation technology that is used to map chest vibrations in order to identify the best placement location on the chest.
Unlike traditional ECG measurement methods that require going into a doctor's office, where heart health can be monitored only for a couple of minutes at a time, say the researchers, their device can be worn for days, providing constant heart monitoring. Looking ahead, the researchers are working on improvements to data collection and storage for the device, as well as ways to power the e-tattoo wirelessly for longer periods.
Recently they developed a smartphone app that not only stores the data safely but can also show a heart beating on the screen in real time. For more, see " A Chest-Laminated Ultrathin and Stretchable E-Tattoo for the Measurement of Electrocardiogram, Seismocardiogram, and Cardiac Time Intervals ."