Researchers shrink wireless devices

James Bond-style technologies such as mobile phones the size of earpieces and invisible sensors sprinkled about to detect toxins are closer to reality.

University of Michigan researchers have worked out how to build wireless systems even smaller while still retaining range and power efficiency.

One obstacle to further shrink small wireless devices has been trying to fit all the components onto one chip but U-M researchers have built a tiny silicon-compatible antenna and frequency resonator that will do just that.

The antenna and resonator are two of the most problematic off-chip components in wireless systems. The two components require large amounts of space off the chip.

The technology is being developed for use in environmental sensors, but could be applied to mobile phones, laptops and other wireless devices, said Michael Flynn, head of the wireless interface group.

Rather than using a traditional wire antenna, researchers built a slot antenna where, instead of the metal wire, an entire plane is covered with metal, leaving only a slot or groove in the metal bare.

Wire surrounds the groove so it's much more effective at radiating in a small antenna.

Because of the antenna's shape, the wireless system does not need a network to match the antenna's frequency to the rest of the electronic device.

The second component U-M scientists replaced is the quartz frequency resonator, which allows a wireless device to focus on a specific signal and ignore others.

Instead of quartz, the scientists used MEMS-based technology to build the resonator that can be fitted onto the chip. It functions similarly to how the rim of a wine glass vibrates when flicked by a finger. The wine-glass rim design helps retain the purity of the signal.