Source: Nanoworld
Date: 31 May 2005

Nano World: New cell phones from nanotech


NEW YORK, May 31 (UPI) -- Nanotechnology soon could enhance cell phones with carbon-nanotube vacuum tubes, microscopic microphones, liquid lenses, compasses linked with global positioning system satellites and even electronic noses.

"Nanotechnology is all about small, light and cheap, and you're not in the cell phone business if you're not thinking small, light and cheap -- the two are made for each other," said David Bishop, vice president of research at Lucent's Bell Labs in Murray Hill, N.J.

As proof of principle, Bishop said Bell Labs researchers are developing nano-scale phones for the U.S. Defense Advanced Research Projects Agency consisting of radio transmitters about the diameter of a human hair. The transmitters could be used to look at processes within living cells and measure chemical potentials, electric fields and pressures.

"It's also an opportunity to shrink existing technology to its practical limits," Bishop told UPI's Nano World.

The parts of mobile phones that help send and receive data rank among their most expensive and energy-draining components.

"With nanotechnology, you can lower costs, increase functionality and lower power," Bishop said at a meeting of the NanoBusiness Alliance in New York.

The radio-frequency amplifiers used in cell phones are hot tungsten filaments, typically with power efficiencies of just 10 percent. "Those chew up a lot of battery power," Bishop said.

Instead, arrays of carbon nanotubes grown on silicon plates could serve as high-efficiency electron-emitting vacuum tubes of the same time used in old-fashioned conventional phones, but at a fraction of the power requirements.

Likewise, Bell Labs researchers are developing more efficient filters of unwanted signals using nano-scale piezoelectric stacks and high-performance inductors created using self-assembly techniques.

The researchers also are designing components called micro-microphones for future telephones that sport more than one microphone for sound reception.

"We have two ears to help locate sounds in space. This helps us focus in on a single conversation in a noisy room. Having multiple microphones would allow us to be maximally sensitive to the sounds we want and minimally sensitive to the sounds we don't," Bishop explained. "This would help cut down the noise you hear over the phone.

He said Bell Labs researchers are creating micro-microphones with self-assembly and nano-engineering of silicon membranes and various composite materials "for lower-cost, easy-to-integrate electronics."

To mimic the human eye more closely, the researchers also are creating liquid lenses that can fit into mobile phones.

"In the fixed lenses you have in cell phones, what happens is there is a lot of jitter, the image is a mess, but your eyes stay focused on what they're looking at -- do jitter reduction. So we want to make our optics as functional as what our own eyes have," Bishop said.

Because the lens is liquid, under electric control it can alter its focus. The lens is squeezed between transparent plates coated with nano-films that allow the liquids to move without viscosity, permitting the lens to change rapidly to stay focused on a target. "They're small, low power and cheap," Bishop said.

A company called mPhase Technologies in Norwalk, Conn., is partnering with Bell Labs to develop intelligent batteries via nanotechnology. Batteries consist of metal electrodes bathed in chemicals known as electrolytes. Plugging in a battery leads to electrolytes reacting, with electrons streaming through the electrodes. Over time, the electrolytes react on their own, which is why battery power drains even when they are not in use.

The company is developing a battery crafted via semiconductor industry processes that contain millions of silicon nanotubes, atop each sits a droplet of electrolyte. If made to fall within the space between the tubes by applying a voltage change, the droplets react to create a current. This means the electrolytes activate only when in use.

"We have a working battery in the lab right now in Murray Hill," Steve Simon, mPhase's executive vice president for research and development, told Nano World.

The nanotechnology-enabled battery is not rechargeable, but in the future the researchers hope to create rechargeable batteries with much larger surface areas that could be recharged more quickly, Bishop noted.

Simon's company also is working on nano-magnetometers, essentially, tiny compasses. When coupled with GPS units, not only will phones be able to display latitude, longitude and altitude information, but they also know which way they are facing.

"That way, you can use services that gives directions over the phone," Simon said.

For the communications networks underlying the phones, Bell Labs researchers are creating soccer-ball-sized devices that can handle a petabit -- or a million billion bits -- of data.

"If everyone with a phone made a phone call at the same time, that would be about a petabit of data. To switch a petabit of data, you'd need a city full of electronics powered by a nuclear powerplant," Bishop said.

The petabit switch uses micromirrors created by self-assembly and nano-patterning onto silicon to handle both laser and electric pulses for many times greater efficiency and information density.

In the future, phones may pack nanosensors that act as artificial noses to detect airborne chemicals.

"The goal is to not limit cell phones just to just audio or video, but to have odor sensors, vibration sensors, the full suite of sensors you have in biology," Bishop said.
Nanotechnology : big unknowns
Nanotechnology and gene therapy
Nanomaterials Extend Life Of Brain Cells