Fogless Windshields Enabled by Nanotechnology

The CNT Windshield Coating is designed to eliminate this windshield condensation. 
(Photo: Fraunhofer Technology Development)

On cold mornings, a driver's vision is often blurred by moisture precipitating on the inside of the windshield. This happens when warm, humid air comes into contact with a cold surface. 

Condensation can be prevented by increasing the volume of air (opening the windows), by heating the whole of the vehicle's interior or by heating the windshield to a temperature above the dew point.

Ivica Kolaric of the Fraunhofer Technology Development Group TEG in Stuttgart favors the third option. His new process warms up the windshield, not with costly copper heating elements but with a transparent coat of carbon lacquer, or more exactly, carbon nanotubes (CNTs). Kolaric and his team are currently working on a bonding system, for release a year or two from now, that could keep not only windshields, but also bathroom mirrors and other surfaces free from condensation. 

When attached to an electricity supply, the lacquer coating is transformed into a wide, flat heater that exactly covers the surface to be heated. It continues to function even when it is damaged in places. 

If a standard heated windshield has one of its wires severed, the entire heater often ceases to function. For the CNT heater, however, a few small defects in the coating are not a problem, says Kolaric, because the current flows over the whole surface. 

A further advantage of the "flat" conductor is its uniform heat distribution, says Kolaric. Every single point on the surface of the windshield is heated evenly, rather than the warmth radiating outward from the heating elements. The CNT coating itself does not store any heat. 

"The lacquer converts the electricity almost entirely into warmth and transfers this to the windshield," explains Kolaric. The windshield is clear in a very short time with minimal power consumption. "What's more," he stresses, "the CNT resistance heater can be integrated in the vehicle's standard 12-volt power supply."

(Source: Fraunhofer Technology Development Group)