11 August 2011,
esearchers have developed ultrathin electronics that can be placed on the skin as easily as a temporary tattoo, and hope the new devices will pave the way for sensors that monitor heart and brain activity without bulky equipment, or perhaps computers that operate via the subtlest voice commands or body movement.
Flexible electronics have been around for a few years; one approach is to write circuits onto materials that are already flexible, another is to make the circuits themselves flexible. In 2008, for example, engineers at the University of Tokyo created a conductive material that looked a bit like a fishnet stocking. Made of carbon nanotubes and rubber, it could stretch by more than a third of its natural length, possibly enough to make robots become more agile.
The problem with these past attempts, says materials scientist John Rogers of the University of Illinois, Urbana-Champaign, is that none of them has been as stretchy and as bendy as human skin.
Now, Rogers and his colleagues at Urbana-Champaign and other institutions in the United States, Singapore, and China have come up with a form of electronics that almost precisely matches skin's mechanical properties. Known as epidermal electronics, they can be applied in a similar way to a temporary tattoo: you simply place it on your skin and rub it on with water (see video). The devices can even be hidden under actual temporary tattoos to keep the electronics concealed.
Researchers hope it could replace bulky equipment currently used in hospitals:
A mass of cables, wires, gel-coated sticky pads and monitors are currently needed to keep track of a patient's vital signs. Scientists say this can be "distressing", such as when a patient with heart problems has to wear a bulky monitor for a month "in order to capture abnormal but rare cardiac events".
In one study the tattoo was used to measure electrical activity in the leg, heart and brain. It found that the "measurements agree remarkably well" with those taken by traditional methods.
Smaller, less invasive, sensors could be especially useful for monitoring premature babies or for studying patients with sleep apnoea without them wearing wires through the night, researchers say.