High school teacher

creates microfluidic devices

using a photocopier

A high school physics teacher has invented a method of producing microfluidic devices, using little else than a photocopier and transparency film

Microfluidic technology, in which liquid is made to pass through “microchannels” that are often less than a millimeter in width, has had a profound effect on fields such as physics, chemistry, engineering and biotechnology. In particular, it has made “lab-on-a-chip” systems possible, in which the chemical contents of tiny amounts of fluid can be analyzed on a small platform. Such devices are typically made in clean rooms, through a process of photolithography and etching. This rather involved production method is reflected in their retail price, which sits around US$500 per device. Now, however, a high school teacher has come up with a way of making microfluidics that involves little else than a photocopier and transparency film.

Joe Childs, who teaches physics at Massachusetts’ Cambridge Rindge and Latin School, collaborates with Harvard University’s School of Engineering and Applied Sciences (SEAS), via the National Science Foundation’s Research Experience for Teachers program. As part of that program, he devised a quick, simple and inexpensive method of creating reusable labs-on-a-chip.

He starts by designing the layout of the microchannels in PowerPoint, printing that image, then photocopying it onto a sheet of classroom-style transparency film. The same sheet is ran through the photocopier repeatedly, until the ink builds up sufficiently to create a raised relief model of the channels. That model serves as a negative mold, which is used to create the final working channels in a polymer chip.

Childs is now working with SEAS Director of Instructional Technology Dr. Anas Chalah, to perfect the system. Already, he says, they can design and build a chip in a single afternoon. Although the photocopier microfluidics are not as precise as their commercially-produced counterparts, they could prove to be an invaluable educational aid for physics students, who will be able to design and build their own microfluidic devices.

All photos courtesy Harvard University.

Sourced & published by Henry Sapiecha

Spray-on film turns windows into solar panels

Imagine if all the windows of a building, and perhaps even all its exterior walls, could be put to use as solar collectors. Soon, you may not have to imagine it, as the Norweigan solar power company EnSol has patented a thin film solar cell technology designed to be sprayed on to just such surfaces. Unlike traditional silicon-based solar cells, the film is composed of metal nanoparticles embedded in a transparent composite matrix, and operates on a different principle. EnSol is now developing the product with help from the University of Leicester’s Department of Physics and Astronomy. Read More

Sourced & published by Henry Sapiecha

Innovation Puts Next-Generation

Solar Cells on the Horizon.

Could dye from berries be the answer??

ScienceDaily (Dec. 2, 2009) — In a world first, a Monash University-led international research team has developed an innovative way to boost the output of the next generation of solar cells.

Scientists at Monash University, in collaboration with colleagues from the universities of Wollongong and Ulm in Germany, have produced tandem dye-sensitised solar cells with a three-fold increase in energy conversion efficiency compared with previously reported tandem dye-sensitised solar cells.

Lead researcher Dr Udo Bach, from Monash University, said the breakthrough had the potential to increase the energy generation performance of the cells and make them a viable and competitive alternative to traditional silicon solar cells.

Dr Bach said the key was the discovery of a new, more efficient type of dye that made the operation of inverse dye-sensitised solar cells much more efficient.

When the research team combined two types of dye-sensitised solar cell — one inverse and the other classic — into a simple stack, they were able to produce for the first time a tandem solar cell that exceeded the efficiency of its individual components.

“The tandem approach — stacking many solar cells together — has been successfully used in conventional photovoltaic devices to maximise energy generation, but there have been obstacles in doing this with dye-sensitised cells because there has not been a method for creating an inverse system that would allow dye molecules to efficiently pass on positive charges to a semiconductor when illuminated with light,” Dr Bach said.

“Inverse dye-sensitised solar cells are the key to producing dye-sensitised tandem solar cells, but the challenge has been to find a way to make them perform more effectively. By creating a way of making inverse dye-sensitised solar cells operate very efficiently we have opened the way for dye-sensitised tandem solar cells to become a commercial reality.”

Although dye-sensitised solar cells have been the focus of research for a number of years because they can be fabricated with relative simplicity and cost-efficiency, their effectiveness has not been on par with high-performance silicon solar cells.

Dr Bach said the breakthrough, which is detailed in a paper published in Nature Materials, was an important milestone in the ongoing development of viable and efficient solar cell technology.

“While this new tandem technology is still in its early infancy, it represents an important first step towards the development of the next generation of solar cells that can be produced at low cost and with energy efficient production methods,” he said.

“With this innovation we are one step closer to the creation of a cost-efficient and carbon-neutral energy source.”

Sourced and published by Henry Sapiecha 8th June 2010

Hold Secret

to Affordable Solar Power Worldwide

Science(Apr. 30, 2010) — Pokeberries — the weeds that children smash to stain their cheeks purple-red and that Civil War soldiers used to write letters home — could be the key to spreading solar power across the globe, according to researchers at Wake Forest University’s Center for Nanotechnology and Molecular Materials.

Nanotech Center scientists have used the red dye made from pokeberries to coat their efficient and inexpensive fiber-based solar cells. The dye acts as an absorber, helping the cell’s tiny fibers trap more sunlight to convert into power.

Pokeberries proliferate even during drought and in rocky, infertile soil. That means residents of rural Africa, for instance, could raise the plants for pennies. Then they could make the dye absorber for the extremely efficient fiber cells and provide energy where power lines don’t run, said David Carroll, Ph.D., the center’s director.

“They’re weeds,” Carroll said. “They grow on every continent but Antarctica.”

Wake Forest University holds the first patent for fiber-based photovoltaic, or solar, cells, granted by the European Patent Office in November. A spinoff company called FiberCell Inc. has received the license to develop manufacturing methods for the new solar cell.

The fiber cells can produce as much as twice the power that current flat-cell technology can produce. That’s because they are composed of millions of tiny, plastic “cans” that trap light until most of it is absorbed. Since the fibers create much more surface area, the fiber solar cells can collect light at any angle — from the time the sun rises until it sets.

To make the cells, the plastic fibers are stamped onto plastic sheets, with the same technology used to attach the tops of soft-drink cans. The absorber — either a polymer or a less-expensive dye — is sprayed on. The plastic makes the cells lightweight and flexible, so a manufacturer could roll them up and ship them cheaply to developing countries — to power a medical clinic, for instance.

Once the primary manufacturer ships the cells, workers at local plants would spray them with the dye and prepare them for installation. Carroll estimates it would cost about $5 million to set up a finishing plant — about $15 million less than it could cost to set up a similar plant for flat cells.

“We could provide the substrate,” he said. “If Africa grows the pokeberries, they could take it home.

“It’s a low-cost solar cell that can be made to work with local, low-cost agricultural crops like pokeberries and with a means of production that emerging economies can afford.”

Sourced and published by Henry Sapiecha 3rd May 2010

On Butterfly Wings

Inspire More Powerful Solar Cells

ScienceDaily (Feb. 5, 2009) — The discovery that butterfly wings have scales that act as tiny solar collectors has led scientists in China and Japan to design a more efficient solar cell that could be used for powering homes, businesses, and other applications in the future.

In the study, Di Zhang and colleagues note that scientists are searching for new materials to improve light-harvesting in so-called dye-sensitized solar cells, also known as Grätzel cells for inventor Michael Grätzel. These cells have the highest light-conversion efficiencies among all solar cells — as high as 10 percent.

The researchers turned to the microscopic solar scales on butterfly wings in their search for improvements. Using natural butterfly wings as a mold or template, they made copies of the solar collectors and transferred those light-harvesting structures to Grätzel cells. Laboratory tests showed that the butterfly wing solar collector absorbed light more efficiently than conventional dye-sensitized cells. The fabrication process is simpler and faster than other methods, and could be used to manufacture other commercially valuable devices, the researchers say.

Sourced and published by Henry Sapiecha 15th April 2010