This innovative device, capable of directly sensing and controlling activity in animal tissue, can produce high-density maps of the electrical activity produced by a beating heart, with better resolution and speed than that of conventional cardiac monitoring technology.

Published in the journal Science Translational Medicine (Viventi et al., doi: 10.1126/scitranslmed.3000738), the research demonstrates silicon nanomembrane transistors configured to record electrical activity directly from the curved, wet surface of a beating porcine heart in vivo. Also operating when immersed in the body's fluids, this minimally invasive medical technology could allow for the localizing and treatment of abnormal heart rhythms, such as arrythmias or in epilepsy, as well as in new flexible sensors, transmitters and photovoltaic and microfluidic devices.

The research team, from Northwestern University, the University of Illinois at Urbana-Champaign and the University of Pennsylvania, have helped to open up the body's complex electrical networks to examination for the first time, paving the way for more effective implantable medical devices and treatments.

Based on a range of tiny circuit elements connected by metal wire pop-up bridges, the technology allows the wires to pop up when bent or stretched, allowing circuits to be placed on a curved surface. As one of the team leaders, John Rogers, points out, the team were interested “in creating electronics with the performance of conventional, wafer-based devices, but with the mechanical properties of a rubber band.”

With the electronics currently used for heart monitoring being flat and rigid, this device, with its wavy mesh design, can wrap around irregular and curved surfaces, and is thin and stretchable enough to bring electronic circuits right to the tissue with more contact points, which means improved data.

The device uses 288 contact points, rather than the usual 5–10 of standard clinical systems, and more than 2000 transistors positioned closely together. It is this large amount of contact points that gives it an advantage over current medical electronics that fail when any significant bending or stretching occurs.

The team hope that this type of electronics will provide new applications not based on current technologies, ranging from advanced surgical devices, to implants, to wearable monitors. For cardiac monitoring, they are working on devices that can deploy on balloon catheters, and other applications could include similar systems that monitor the brain using a type of brain–computer interface, ultimately in fully implantable forms for long-term use, as well as in bio-inspired device design.