Times of India
26 March 2010

Scientists create a prototype flexible silicon electronics device that can be wrapped around the heart. The device will help treat and monitor irregular heart rhythms; it can also be used to treat epilepsy
Researchers from Northwestern University, the University of Illinois and the University of Pennsylvania have created an electronic sensor that can bend, stretch and twist. This flexible sensor can map waves of electrical activity in the heart with better resolution and speed than existing cardiac monitoring tech.

The thin sensor produces high–density maps of a beating heart’s electrical activity, providing potential means to localise and treat abnormal heart rhythms. The scientists are also the first to demonstrate a flexible silicon electronics device for a medical application. Results of the study are published in the journal Science Translational Medicine.

“The heart is dynamic and not flat, but electronics currently used for monitoring are flat and rigid,” said Northwestern’s Yonggang Huang, a senior author of the paper.

“The device is thin, flexible and stretchable and brings electronic circuits right to the tissue. More contact points mean better data.”

How they did it
The device, capable of directly sensing and controlling activity in animal tissue, is based on flexible electronics developed in 2008 by Huang and his collaborator John Rogers at the University of Illinois.

Huang and Rogers’ so–called “pop–up” technology allows circuits to bend, stretch and twist. Usually any significant bending or stretching to circuits renders an electronic device useless, which is what limits the use of electronics on the body.

Huang and Rogers jumped this sizeable hurdle by creating an array of tiny circuit elements connected by metal wire “pop–up bridges.”

When the array is bent or stretched, the wires – not the circuits – pop up. This approach allows circuits to be placed on a curved surface.

Brian Litt of the University of Pennsylvania, and his colleagues designed the medical experiments and tested the device in a large animal model.

In the experiments conducted at Penn, the team demonstrated that the electronics continue to operate when immersed in the body’s fluids, and the mechanical design allows the device to conform to and wrap around the body’s irregularly shaped tissues. The device uses 288 contact points and more than 2,000 transistors positioned closely together. Standard clinical systems usually have only five to 10 contact points. The new device is also tiny, 14.4 millimeters by 12.8 millimeters, roughly the size of a US nickel.

By bringing electronic circuits right to the tissue, rather than having them located remotely, the device can process signals right at the tissue. This close contact allows the device to have a much higher number of electrodes for sensing or stimulation than is currently possible in medical devices.

The device can collect very large amounts of data from the body, at high speed. Researchers will be able to map the body’s complicated electrical networks in much more detail, with more effective implantable medical devices and treatments likely to emerge.

The future
The current device is not wireless. The next big step in this new generation of implantable devices, say the researchers, will be to find a way to move the power source onto them. One solution could be to have the heart power the device. The technology could also be adpated to make new transmitters, photovoltaic and microfluidic devices as well.