Press releases
Please quote Nature Materials as the source of these items.
April 2007
Plastic power
A flexible plastic sheet that can wirelessly transmit power to electronic devices is described online this week in Nature Materials.
The increasing use of electronic devices, gadgets and sensors in our daily lives places a demand on flexible and convenient power-transmission systems. The wireless transmission system presented by Takao Someya and colleagues is made using printing techniques that are already in use for the large-scale manufacture of organic electronic circuits, and therefore can cover entire floors, walls or desks. The power-transmission sheets use small position-sensing coils that are able to detect similar coils attached to the targeted electronic device. Once a target device is brought near to the transmission sheet, the sheet senses the receiver coils and tiny switches activate the nearest sender coil to transmit a wireless power signal.
The overall efficiency of the transmission is an impressive 81%, and a transfer of up to 40 Watts was achieved. This efficiency as well as the cheap manufacturing process suggest the future common use of such sheets to power electronic devices in everyday environments.
A large-area wireless power-transmission sheet using printed organic transistors and plastic MEMS switches
Tsuyoshi Sekitani et al.
Published online: 29 April 2007 | doi 10.1038/nmat1903
A gel to absorb solvent spills
A gel that swells up to 500 times its size in a range of solvents is reported by Kazuki Sada and colleagues online in Nature Materials this week. The gels should prove useful for absorbing industrial spills.
Polyelectrolyte gels are already known as super-absorbent polymers. Their ability to swell and absorb several hundred times their dry weight of water or other polar solvents means that they find many uses such as in nappies and for absorbing water spills. Until now, however, such gels haven't been effective at absorbing less-polar organic solvents — such as dichloromethane and tetrahydrofuran, which are widely used in industry — because they collapse rather than swell. Sada and colleagues have simply added bulky side-groups that are more attractive to less-polar solvents onto the polyelectrolyte molecules. This enables the gels to swell rather than collapse.
Lipophilic polyelectrolyte gels as super-absorbent polymers for nonpolar organic solvents
Toshikazu Ono, Takahiro Sugimoto, Seiji Shinkai & Kazuki Sada
Published online: 29 April 2007 | doi 10.1038/nmat1904
The smallest pipette
A pipette that dispenses zeptolitre droplets — a million-trillionth of a litre and containing between 10,000 and a million atoms — is described online this week in Nature Materials.
Eli and Peter Sutter made their pipettes from germanium nanowires with a reservoir of germanium-gold alloy at one end. Next they covered both the nanowire and reservoir in a few thin layers of carbon. The pipette was then heated and a hole punctured in the reservoir end of the carbon shell, through which the alloy escapes to form a droplet. The dispensed droplets are ideal for studying crystallization in this size regime, which is too large for easy computer simulation, but small enough to show different behaviour from the bulk alloy.
Dispensing and surface-induced crystallization of zeptolitre liquid metal-alloy drops pp363-366
Peter W. Sutter & Eli A. Sutter
Published online: 15 April 2007 | doi 10.1038/nmat1894
Fibre circuits for electronic fabrics
Electronic circuits that could be easily incorporated into fabrics are described online this week in Nature Materials. Wearable electronics open up many possibilities for exploiting new connections between humans and technology; the opportunities for health monitoring and diagnosis are of particular interest.
The fundamental building block of the electronic circuit - the transistor - is very difficult to make in a fabric-friendly way, particularly as most transistors need their dimensions to be finely tuned. Olle Inganäs and colleagues adapted the existing technology of electrochemical transistors, which require less precision in their fabrication, and created circuits from the fibres themselves. They coated the fibres with conducting polymer to create electrodes and joined them together at cross points to make transistors and resistors. The authors then used the arrays of fibres to demonstrate these components in fibre circuits that are capable of logic functions.
