[Editors] MIT works toward cell-sized batteries

[Teresa Herbert]

FOR IMMEDIATE RELEASE
Contact: Teresa Herbert, MIT News Office
T. 617-258-5403, E. therber at mit.edu

Photo available

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MIT engineers work toward cell-sized batteries
--Microbatteries could power tomorrow’s miniature devices
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CAMBRIDGE, Mass. -- Forget 9-volts, AAs, AAAs or D batteries: The  
energy for tomorrow’s miniature electronic devices could come from  
tiny microbatteries about half the size of a human cell and built with  
viruses.

MIT engineers have developed a way to at once create and install such  
microbatteries — which could one day power a range of miniature  
devices, from labs-on-a-chip to implantable medical sensors — by  
stamping them onto a variety of surfaces.

In the Proceedings of the National Academy of Sciences (PNAS) the week  
of Aug. 18, the team describes assembling and successfully testing two  
of the three key components of a battery. A complete battery is on its  
way.

“To our knowledge, this is the first instance in which microcontact  
printing has been used to fabricate and position microbattery  
electrodes and the first use of virus-based assembly in such a  
process,” wrote MIT professors Paula T. Hammond, Angela M. Belcher,  
Yet-Ming Chiang and colleagues.

Further, the technique itself “does not involve any expensive  
equipment, and is done at room temperature,” said Belcher, the  
Germeshausen Professor of Materials Science and Engineering and  
Biological Engineering.

Hammond is the Bayer Professor of Chemical Engineering and associate  
head of the Department of Chemical Engineering. Chiang is a professor  
of ceramics in the Department of Materials Science and Engineering.  
Belcher, Chiang and Hammond are also affiliated with the MIT Energy  
Initiative, which aims to help transform the global energy system to  
meet the needs of the future. Belcher and Hammond are also faculty  
members in the Koch Institute for Integrative Cancer Research at MIT.

Batteries consist of two opposite electrodes — an anode and cathode —  
separated by an electrolyte. In the current work, the MIT team created  
both the anode and the electrolyte.

First, on a clear, rubbery material the team used a common technique  
called soft lithography to create a pattern of tiny posts either four  
or eight millionths of a meter in diameter. On top of these posts,  
they then deposited several layers of two polymers that together act  
as the solid electrolyte and battery separator.

Next came viruses that preferentially self-assemble atop the polymer  
layers on the posts, ultimately forming the anode. In 2006, Hammond,  
Belcher, Chiang and colleagues reported in Science how to do this.  
Specifically, they altered the virus’s genes so it makes protein coats  
that collect molecules of cobalt oxide to form ultrathin wires —  
together, the anode.

The final result: a stamp of tiny posts, each covered with layers of  
electrolyte and the cobalt oxide anode. “Then we turn the stamp over  
and transfer the electrolyte and anode to a platinum structure” that,  
together with lithium foil, is used for testing, Hammond said.

The team concludes in their PNAS paper: “the resulting electrode  
arrays exhibit full electrochemical functionality.”

What’s next? In addition to developing the third part of a full  
battery — the cathode — via the viral assembly technique, the team is  
also exploring a stamp for use on curved surfaces, Belcher said.  
“We’re also interested in integrating [the batteries] with biological  
organisms.”

Additional coauthors of the PNAS paper are first author Ki Tae Nam,  
Ryan Wartena, Pil J. Yoo (now at Sungkyunkwan University, Korea),  
Forrest W. Liau, and Yun Jung Lee.

This work was funded by the Army Research Office Institute of  
Collaborative Biotechnologies, the Army Research Office Institute of  
Soldier Nanotechnologies, and the David and Lucille Packard Foundation.

By Elizabeth Thomson, MIT News Office

# # #


Teresa Herbert
Media Specialist
Massachusetts Institute of Technology
News Office, Room 11-400
Cambridge, MA 02139-4307

Phone: 617-258-5403
Fax: 617-258-8762

therbert at mit.edu




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