With carbon nanotubes, a path to flexible, low-cost sensors: Potential applications range from air-quality monitors to electronic skin

With carbon nanotubes, a path to flexible, low-cost sensors: Potential applications range from air-quality monitors to electronic skin

Carbon nanotube-based gas sensors created at TUM offer a unique combination of characteristics that can't be matched by any of the alternative technologies. They rapidly detect and continuously respond to extremely small changes in the concentrations of gases including ammonia, carbon dioxide, and nitrogen oxide. They operate at room temperature and consume very little power. Furthermore, as the TUM researchers report in their latest papers, such devices can be fabricated on flexible backing materials through large-area, low-cost processes.

Thus it becomes realistic to envision plastic food wrap that incorporates flexible, disposable gas sensors, providing a more meaningful indicator of food freshness than the sell-by date. Measuring carbon dioxide, for example, can help predict the shelf life of meat. "Smart packaging" -- assuming consumers find it acceptable and the devices' non-toxic nature can be demonstrated -- could enhance food safety and might also vastly reduce the amount of food that is wasted. Used in a different setting, the same sort of gas sensor could make it less expensive and more practical to monitor indoor air quality in real time.

Not so easy -- but "really simple"

Postdoctoral researcher Alaa Abdellah and colleagues at the TUM Institute for Nanoelectronics have demonstrated that high-performance gas sensors can be, in effect, sprayed onto flexible plastic substrates. With that, they may have opened the way to commercial viability for carbon nanotube-based sensors and their applications. "This really is simple, once you know how to do it," says Prof. Paolo Lugli, director of the institute.

The most basic building block for this technology is a single cylindrical molecule, a rolled-up sheet of carbon atoms that are linked in a honeycomb pattern. This so-called carbon nanotube could be likened to an unimaginably long garden hose: a hollow tube just a nanometer or so in diameter but perhaps millions of times as long as it is wide. Individual carbon nanotubes exhibit amazing and useful properties, but in this case the researchers are more interested in what can be done with them en masse.

Laid down in thin films, randomly oriented carbon nanotubes form conductive networks that can serve as electrodes; patterned and layered films can function as sensors or transistors. "In fact," Prof. Lugli explains, "the electrical resistivity of such films can be modulated by either an applied voltage (to provide a transistor action) or by the adsorption of gas molecules, which in turn is a signature of the gas concentration for sensor applications."

And as a basis for gas sensors in particular, carbon nanotubes combine advantages (and avoid shortcomings) of more established materials, such as polymer-based organic electronics and solid-state metal-oxide semiconductors. What has been lacking until now is a reliable, reproducible, low-cost fabrication method.

Spray deposition, supplemented if necessary by transfer printing, meets that need. An aqueous solution of carbon nanotubes looks like a bottle of black ink and can be handled in similar ways. Thus devices can be sprayed -- from a computer-controlled robotic nozzle -- onto virtually any kind of substrate, including large-area sheets of flexible plastic. There is no need for expensive clean-room facilities.

"To us it was important to develop an easily scalable technology platform for manufacturing large-area printed and flexible electronics based on organic semiconductors and nanomaterials," Dr. Abdellah says. "To that end, spray deposition forms the core of our processing technology."

Remaining technical challenges arise largely from application-specific requirements, such as the need for gas sensors to be selective as well as sensitive.

This research was partially supported by the German Research Foundation (DFG) through the Cluster of Excellence Nanosystems Initiative Munich (NIM), and by the Bavarian State Ministry for Science, Research and the Arts under the initiative Solar Technologies Go Hybrid.

Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.

MOTOROLA IC Digital Transistors Freescale Semiconductor Multi-units Transistors ST Diodes Fast Recovery Diodes SANYO IC Low Ohmic Resistors TOSHIBA Diodes Transistors VISHAY IC Fleld Effect Transistors AVX Resistors NXP Transistors Switching Diodes LED Chip Fuses Cypress IC NEC Transistors Transistors Freescale LITTELFUSE Diodes Other Parts TI IC TDK IC Civil IC Current Sensors Resistors MAXIM IC Switches HARRIS IC INTERSIL IC Thin Film Resistors Kingbrigt LED Xilinx IC PANASONIC Resistors Resistor Arrays Voltage Regulators Transistors ON Diodes MURATA IC Capacitor LINEAR IC
http://www.suvsystem.com/a/6171.aspx