A wearable technology made from stretchy, lightweight material could make heart health monitoring easier and more accurate than existing electrocardiograph machines — a technology that has changed little in almost a century.
The electronic tattoo (e-tattoo) technology is graphene-based and is placed on the skin to measure a variety of body responses, from electrical to biomechanical signals. The device is so lightweight and stretchable that it can be placed over the heart for extended periods with little or no discomfort. It also measures cardiac health in two ways, taking electrocardiograph (ECG) and seismocardiograph (SCG) readings simultaneously. ECG records the rates of electrical activity produced each time the heart beats; SCG is a measurement technique using chest vibrations associated with heartbeats. Powered remotely by a smartphone, the e-tattoo is the first ultrathin and stretchable technology to measure both ECG and SCG.
ECG readings alone are not accurate enough for determining heart health but they provide additional information when combined with SCG signal recordings. Like a form of quality control, the SCG indicates the accuracy of the ECG readings.
Although soft e-tattoos for ECG sensing are not new, other sensors such as the SCG sensor are still made from non-stretchable materials, making them bulky and uncomfortable to wear. The e-tattoo is made of a piezoelectric polymer called polyvinylidene fluoride that is capable of generating its own electric charge in response to mechanical stress. The device also includes 3D digital image correlation technology that is used to map chest vibrations in order to identify the best location on the chest to place the e-tattoo.
Usually, an ECG measurement requires going to a doctor’s office where heart health can be monitored only for a couple of minutes at a time. This device can be worn for days, providing constant heart monitoring. A smartphone app stores the data safely and shows a heart beating on the screen in real time.