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The microscopic filter that could mean the end of dropped calls on your mobile

This image from a scanning electron microscope shows a tiny mechanical device, an electrostatically-actuated nanoresonator, that might ease congestion over the airwaves to improve the performance of mobile phones.

Researchers have learned how to mass produce tiny mechanical devices that could mean the end of dropped calls and slow download speeds on mobile phones.
The tiny filters are designed to ease congestion over the airwaves.
'There is not enough radio spectrum to account for everybody's handheld portable device,' said Jeffrey Rhoads of Purdue University, who led the research.
The overcrowding results in dropped calls, busy signals, poor call quality and slower downloads. 


The heart of the device is a silicon beam attached at two ends. 
The beam, which vibrates in the center like a skipping rope, is about two microns long and 130 nanometers wide, or about 1,000 times thinner than a human hair. 
Applying alternating current to the beam causes it to selectively vibrate side-to-side or up and down and also allows the beam to be finely adjusted, or tuned.
The nanoresonators were shown to control their vibration frequencies better than other resonators. 
The devices might replace electronic parts to achieve higher performance and lower power consumption.
To solve the problem, the mobile phone industry is trying to build systems that operate with more sharply defined channels so that more of them can fit within the available bandwidth.
'To do that you need more precise filters for cell phones and other radio devices, systems that reject noise and allow signals only near a given frequency to pass,' said Saeed Mohammadi, who is also working on the project.
The Purdue team has created devices called nanoelectromechanical resonators, which contain a tiny beam of silicon that vibrates when voltage is applied. 
Researchers have shown that the new devices are produced with a nearly 100 percent yield, meaning nearly all of the devices created on silicon wafers were found to function properly.
The breakthrough could end the annoyance of dropped calls and slow download speeds on mobile phones
The breakthrough could end the annoyance of dropped calls and slow download speeds on mobile phones

'We are not inventing a new technology, we are making them using a process that's amenable to large-scale fabrication, which overcomes one of the biggest obstacles to the widespread commercial use of these devices,' Rhoads said.
In addition to their use as future cell phone filters, the nanoresonators also could be used for advanced chemical and biological sensors in medical and homeland-defense applications and possibly as components in computers and electronics. -DM