Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Haute Couture from the Experimental Physics Lab

26.09.2006
A team of Austrian physicists has recently developed ultra-thin pressure sensors that can also be processed into sensitive textiles.

The breakthrough came with the arrival of technology for building up a sufficiently large electrical field in polymer foams. This enabled thin-film transistors to switch in reaction to pressure. Possible applications arising from this project funded by the Austrian Science Fund FWF include ultra-thin microphones, pressure sensors for replacement skin, and interactive clothing.

Concepts such as flat and ultra-thin are the latest big thing in the electronics industry, as can be seen from the flatscreens all around us. Applications of this type are made possible by means of thin-film transistors (TFT). Pressure sensitive foils have also been around for some time. Known as ferroelectrets, these are electrically charged polymer foams that generate an electrical signal in reaction to pressure. It has not been possible in the past to use this signal to switch thin-film transistors. However, a joint Austrian and American team has recently achieved precisely this – a breakthrough in the development of ultra-thin, pressure-sensitive switches that have a range of potential applications as a result of their sensitivity and low production costs.

ELECTRO-SANDWICH

"The key factor is the correct coating of the components," explains project manager Prof. Siegfried Bauer from the Institute of Experimental Physics at the Johannes Kepler University in Linz. "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 sides of the individual cavities in the foam converge and produce an electrical signal. Prof. Bauer explains: "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. Previously similar experiments only created permanent switching of the transistor. The transistor did not revert to its original state. That is naturally not ideal for a pressure sensor. It would still generate a signal even if the pressure were released."

FUNCTIONAL RESEARCH

The practical benefits of the work conducted by the team made up of Prof. Bauer and his colleagues at Princeton University in the U.S. stem from two facts. First the pressure sensitivity is high and exists at different pressure intensities, and second the materials used are cheap.

Prof. Bauer explains: "The pressure sensitivity of the sensor in our measurements ranged from just a few pascals to one megapascal. This is a difference of six orders of magnitude. A voltage of up to 100 V was measured, which is more than enough to switch the transistors. In fact, our calculations showed that the voltages could reach up to 340 V, but these could not be measured directly due to the capacities in the measuring apparatus." This sensitivity means that the technology could be used as a microphone, for example. This is because a volume of 100 dB corresponds to a pressure of only 2 pascals. Prof. Bauer’s team has in fact been able to demonstrate a linear relationship between the air pressure and the voltage produced using a prototype of an ultra-thin microphone.

The favorable production costs of the materials used is a further reason suggesting that the new development from this FWF project will find practical application. For example, the propylene used for the polymer foams is now being employed both in the home and in the packaging and automotive industries – even without any use being made so far of its property as a ferroelectret. The prices of TFTs are also constantly falling and, if these two components are placed on a flexible substrate, there is very little standing in the way of them being used as a pressure sensor in artificial skin or as a textile. Fashionista beware: Designed by FWF on a catwalk near you.

Original publication: Flexible ferroelectret field-effect transistor for large-area sensor skins and microphones. Graz et al., Applied Physics Letters 89, 073501 (2006)

Till C. Jelitto | alfa
Further information:
http://www.prd.at
http://www.fwf.ac.at/en/public_relations/press/pv200609-en.html

More articles from Physics and Astronomy:

nachricht Witnessing turbulent motion in the atmosphere of a distant star
23.08.2017 | Max-Planck-Institut für Radioastronomie

nachricht Heating quantum matter: A novel view on topology
22.08.2017 | Université libre de Bruxelles

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>