A hot idea for insulating tiny batteries

Jan 10, 2007

Engineering physics researchers are devising a unique "blanket" that will enable them to squeeze as much electricity as possible from nuclear-powered batteries the size of a grain of coarse salt.

Such batteries, which exploit the natural decay of radioisotopes to generate electricity, could provide virtually indefinite power for micro-technologies like fly-sized robots for military applications or sensors that monitor a building's health.

Other technologies such as fuel cells, chemical batteries or turbine generators also might work in micro-scale applications, says Professor James Blanchard. "But all of them are short-lived," he says. "They either need to be recharged or refueled. Our niche is things that need to be placed and ignored, and just keep running for years."

Nuclear microbatteries convert heat or energy to electricity more efficiently when they are hot, so it makes sense to insulate them, says Blanchard. "The better the insulation, the hotter the source gets, so the more efficient the battery can be," he says.

However, insulating a millimeter-square battery in a way that minimizes heat loss is no easy task. Multifoil insulation is an effective macro-level insulator that combines several thin layers of foil each separated by a vacuum. "They work because they're radiating heat from one layer to another, as opposed to conducting heat through a solid," says Blanchard.

For the microscale, however, multifoil insulation is far too thick.

So, capitalizing on the layered concept, which reduces heat radiation for a fixed temperature drop, Blanchard and graduate student Rui Yao decided to sandwich semicircular silicon oxide pillars-poor conductors-between very thin silicon sheets.

"You want as little conduction through these pillars as possible," says Blanchard.

They developed elaborate computer models to study the heat radiation and conduction of their microscale insulaton. And, using Wisconsin Center for Applied Microelectronics clean room facilities, Yao constructed silicon prototypes.

He now is experimentally verifying what his computer models suggest-that heat is radiating through the silicon layers without much heat loss. "The prototypes he built are a little thicker than the ones we ultimately want to get, but they're consistent with his models," says Blanchard.

Funded by a three-year, $300,000 Department of Energy grant and inspired by an earlier collaboration with Sandia National Laboratory researchers, Blanchard and Yao are still testing and refining the insulation. Implementation for this promising technology, they say, is a couple of years down the road.

"It looks like we'll have an effective insulator that's better than any solid-and better, even, than some of the multi-foil insulations that you can buy commercially," says Blanchard.

Source: University of Wisconsin

Explore further: Heat makes electrons spin in magnetic superconductors

Related Stories

Classroom acoustics for architects

6 hours ago

The Acoustical Society of America (ASA) has published a free online booklet for architects to aid in the application of ANSI/ASA S12.60-2010/Part 1-American National Standard Acoustical Performance Criteria, Design Requirements, ...

Recommended for you

Heat makes electrons spin in magnetic superconductors

13 hours ago

Physicists have shown how heat can be exploited for controlling magnetic properties of matter. The finding helps in the development of more efficient mass memories. The result was published yesterday in Physical Review Le ...

ICARUS neutrino experiment to move to Fermilab

Apr 23, 2015

A group of scientists led by Nobel laureate Carlo Rubbia will transport the world's largest liquid-argon neutrino detector across the Atlantic Ocean from CERN to its new home at the US Department of Energy's ...

National security on the move with high energy physics

Apr 23, 2015

Scientists are developing a portable technology that will safely and quickly detect nuclear material hidden within large objects such as shipping cargo containers or sealed waste drums. The researchers, led ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.