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 A two-atom quantum duet
12.11.2018 | Institute for Basic Science

nachricht Improving understanding of how the Solar System is formed
12.11.2018 | Goethe-Universität Frankfurt am Main

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: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

Im Focus: Nanorobots propel through the eye

Scientists developed specially coated nanometer-sized vehicles that can be actively moved through dense tissue like the vitreous of the eye. So far, the transport of nano-vehicles has only been demonstrated in model systems or biological fluids, but not in real tissue. The work was published in the journal Science Advances and constitutes one step further towards nanorobots becoming minimally-invasive tools for precisely delivering medicine to where it is needed.

Researchers of the “Micro, Nano and Molecular Systems” Lab at the Max Planck Institute for Intelligent Systems in Stuttgart, together with an international...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

In focus: Peptides, the “little brothers and sisters” of proteins

12.11.2018 | Life Sciences

Materials scientist creates fabric alternative to batteries for wearable devices

12.11.2018 | Materials Sciences

A two-atom quantum duet

12.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>