PHOTO ILLUSTRATION DAVID SWANN / DSWANN@STARBULLETIN.COM

A Maui-based company harnesses ambient radiation as a source of power for devices

From communications towers to kitchen microwaves, from sunshine to hot sidewalks, energy radiates all around us. But much of it is wasted, like unfinished meals tossed out at a restaurant.

But now a Hawaii technology team has come up with a way to tap into that wasted energy, much like conscientious restaurants recycle food.

One of the key researchers, University of Hawaii scientist Bor Yann Liaw, has called it the "recycling of radio waste."

The possible applications are mind-boggling.

The most obvious, near-term uses include smoke alarms, burglar alarms or other sensors that never need a battery change. They simply recharge themselves with a device that harvests the electromagnetic waves, or photons, that already flood the space around them from a myriad of sources.

The innovation carries huge ramifications in terms of reduced labor and battery disposal. Batteries contain toxic heavy metals that can contaminate the environment.

Photon-harvesting or beam-scavenging technology has military and homeland security applications, too.

Just last week, the company, Ambient Micro LLC, based at the Maui Research & Technology Center, received approval from the Air Force for a $100,000 research contract to develop a prototype power supply for sensors on small unmanned aerial vehicles (UAVs), or drones.

Using such technology in the not-too-distant future, military combat patrols and police SWAT teams could send bumblebee-size or even housefly-size drones into a bunker or house for reconnaissance.

"They're trying to make things smaller, but the smaller you make them, that's when power becomes a problem," says Ambient Micro President Scott Weeker. "Ambient energy is free, clean, natural energy. The bad news is that the amount of energy from these sources is still fairly small. It's not yet practicable to power an electric car or even a laptop. The good news is that the amount of power needed for new devices is dropping rapidly."

COURTESY R. FEARING / UC-BERKELEY Robofly is a stealth robotic flier that is actually the size of a fly. Squads of roboflies might one day be sent to search out targets, collect and provide information on damage assessment, or search for chemical and biological warfare agents.

"The emergence of ambient energy as a viable alternative power source is really driven by the advancements in semiconductor design," he says. "Things that used to require watts of power are now running on milliwatts and will soon only require microwatts."

Homeland security is another area that could benefit: All or parts of the U.S.-Mexican border could be fitted with sensors that would operate on the invisible grid of energy that already permeates most of North American airspace.

In the longer term, microscopic scanners powered by ambient energy could swim through the bloodstream looking for diseased tissue, not unlike the plot of the 1966 movie "Fantastic Voyage."

Cans or packages on store shelves could file their own inventory reports using radio-frequency tags. Perishable goods could send a signal to stock clerks when they pass their expiration date.

But the first use of the technology might be for tracking endangered desert tortoises at Edwards Air Force Base, Calif.

"Since they are endangered, the Air Force can't run their tests if the tortoises are on the test range," says Weeker. "However, since the adult tortoises have the habit of burrowing underground, the best way to track them is to put a tracking tag on their babies. The technical challenge of developing a very small RF (radio frequency) tracking tag that fits on the back of a baby desert tortoise may lead to many defense and commercial applications for low-cost, active and passive tracking of equipment, vehicles and people."

The firm has teamed up with Trex Hawaii on the project.

Ambient Micro's goal is to develop a tiny device that harvests not only photons (visible light and invisible electromagnetic radiation), but also converts sound waves, vibrations and hot-cold temperature differences into power.

The company was established in 2001 as HawaiiWave High Speed Wireless Networks and, in conjunction with Oceanic Time Warner Cable, developed the first hotel and condo high-speed Internet service using digital cable.

In late 2004 the company received $90,000 from the Hawaii Technology Development Venture and the Office of Naval Research to look into ambient radio signals as a source of alternative energy. Last year, it received a follow-on contract of $300,000 to develop a power supply prototype based on the new technology.

In October the company was restructured and incorporated as Ambient Micro with John Langley, former general manager of Raytheon Wireless Solutions, as chief technology officer. The chief scientist is Liaw, director of the Electrochemical Power Systems Laboratory at UH-Manoa.