Haute couture from the Experimental Physics lab

Ferroelectrets, electrically charged polymer foams that can switch on thin film transistors, could have a future being incorporated into sensitive textiles.

A team of Austrian physicists has developed the foam which, under pressure, generates sufficient power to switch on the transistors. As the pressure decreases, the devices are switched off.

These ultra-thin pressure sensors could be used in microphones, pressure sensors for replacement skin and interactive clothing.

"The key factor is the correct coating of the components," Professor Siegfried Bauer, project manager, from the Institute of Experimental Physics at the Johannes Kepler University in Linz, says.

"We applied a propylene foam over a TFT on a polyimide base. These are the type of TFTs we know from flatscreens."

The polymer propylene foam is the actual sensor. When pressed, the differently charged side of the individual cavities in the foam converge and produce an electrical signal.

"The great thing about this combination is that the transistor switches only temporarily. If the pressure on the propylene layer decreases, the transistor reverts to its original state. Earlier experiments only created permanent switching," Bauer says.