Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Green, leafy spinach may soon power cellphones and laptops

21.09.2004


For the first time, MIT researchers have incorporated a plant’s ability to convert sunlight to energy into a solid-state electronic “spinach sandwich” device that may one day power laptops and cell phones.



At the heart of the device is a protein complex dubbed Photosystem I (PSI). Derived from spinach chloroplasts, PSI is 10 to 20 nanometers wide. Around 100,000 of them would fit on the head of a pin. “They are the smallest electronic circuits I know of,” said researcher Marc A. Baldo, assistant professor of electronic engineering and computer science at MIT.

Baldo and other researchers from MIT, the University of Tennessee and the U.S. Naval Research Laboratory, including electrical and biomedical engineers, nanotechnology experts and biologists, collaborated on the world’s first solid-state photosynthetic solar cell. The work was reported in NanoLetters, a publication of the American Chemical Society. “We have crossed the first hurdle of successfully integrating a photosynthetic protein molecular complex with a solid-state electronic device,” Baldo said.


Plants’ ability to generate energy has been optimized by evolution, so a spinach plant is extremely efficient, churning out a lot of energy relative to its size and weight. But combining biological and non-biological materials in one device has stymied researchers in the past. Biological materials need water and salt to survive—both are deadly for electronics.

From wet to dry

A new twist in the current work is a membrane of peptide surfactants—similar to the main ingredient in soap—that helped the photosynthetic complexes self-assemble and stabilize while the circuit was fabricated.

So far, scientists and engineers’ efforts to harness the photosynthetic properties of green plants have been most successful with naturally soft organic materials in liquid solutions. But if organic solar cells are to be practical for commercial devices, they need to be integrated with solid-state electronics. The researchers ground up ordinary spinach and purified it with a centrifuge to isolate a protein deep within the cell.

The resulting dark green pellets that smell like cut grass were purified still further and coaxed into a water-soluble state. One of the challenges was to keep the proteins in the same configuration as they appear naturally in the organism. Here’s where peptides come in. The 80,000-plus kinds of proteins in our body, when in fragments called peptides, transform themselves like tiny LEGOs™ into millions of substances. Shuguang Zhang, associate director of MIT’s Center for Biomedical Engineering, discovered that these same peptides can be tweaked into forming completely new natural materials that perform useful functions. One of his designer nanomaterials, which acts like the main ingredient in soaps and detergents, turns out to be ideal for keeping protein complexes functional on a cold, hard surface.

The spinach-sandwich device has no water. Proteins usually need water to survive, but using Zhang’s detergent peptide, the researchers were able to stabilize the protein complexes in a dry environment for at least three weeks. “Detergent peptide turned out to be a wonderful material to keep proteins intact on the surface with electronics,” Zhang said. He speculates that the detergent material has some water trapped within it, similar to the way plant seeds hoard oils that maintain the seeds’ integrity in dry conditions.

Building the sandwich

The bottom layer of the molecular electronic device is transparent glass coated with a conductive material. A thin layer of gold helps the chemical reaction that assembles the spinach chlorophyll Photosystem I complexes. The researchers then evaporate a soft organic semiconductor that prevents electrical shorts and protects the protein complexes from the layer of metal that completes the sandwich.

The researchers shone laser light on the device to create optical excitation, then measured the resulting current. “An important caveat is that we got very little current out, mostly because we had just a thin layer of the complexes in our devices,” Baldo said. “Most of the optical excitation passed straight through without being absorbed. Of the light that was absorbed, we estimate that we converted around 12 percent to charge.”

The researchers hope to achieve a power conversion efficiency of 20 percent or more (which would provide an extremely efficient power source) by creating multiple layers of PSI or assembling them on rough surfaces or 3-D surfaces, like skyscrapers that concentrate a huge amount of surface area within a relatively small space.

Patrick J. Kiley (S.B. 2003) of MIT also worked on this research, which is funded by the Defense Advanced Research Projects Agency, the Air Force Office of Scientific Research, and the National Science Foundation.

A version of this article appeared in the September 15, 2004 issue of MIT Tech Talk (Volume 49, Number 2).

Denise Brehm | EurekAlert!
Further information:
http://www.mit.edu

More articles from Power and Electrical Engineering:

nachricht Stretchable biofuel cells extract energy from sweat to power wearable devices
22.08.2017 | University of California - San Diego

nachricht Laser sensor LAH-G1 - optical distance sensors with measurement value display
15.08.2017 | WayCon Positionsmesstechnik GmbH

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>