Low-cost, implantable electronics on horizon.

• Position: Surgical Technology

New technology under development is paving the way for low-cost electronic devices that work in direct contact with living tissue inside the body. The first planned use of the technology is a sensor that will detect the very early stages of organ transplant rejection.

Paul Berger, professor of electrical and computer engineering and physics at Ohio State University, Columbus, explains that one barrier to the development of implantable sensors is that most existing electronics are based on silicon, and electrolytes in the body interfere with the electrical signals in silicon circuits. Other, more exotic semiconductors might work in the body, but they are more expensive and harder to manufacture.

"Silicon is relatively cheap and it's nontoxic. The challenge is to bridge the gap between the affordable, silicon-based electronics we already know how to build and the electrochemical systems of the human body."

Berger and his colleagues have come up with a new, patent-pending coating that they believe will bridge that gap. In tests, silicon circuits that had been coated with the technology continued to function, even after 24 hours of immersion in a solution that mimicked typical body chemistry.

In the body, electrolytes such as sodium and potassium control nerves and muscles and maintain hydration. They do this by carrying a positive or negative electric charge that spurs important chemical...