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 Long-lived storage of a photonic qubit for worldwide teleportation
12.12.2017 | Max-Planck-Institut für Quantenoptik

nachricht Telescopes team up to study giant galaxy
12.12.2017 | International Centre for Radio Astronomy Research

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>