Manipulating microscopic magnetic beads at MIT

Tue, 25 Sep 2012 14:30:22 GMT

MIT researchers found that arc-shaped magnetic nanotracks could be used most effectively to control the motion of magnetic microbeads across the surface of a silicon wafer. By combining these arcs, they produced configurations such as this, with two "reservoir" rings at top right and left, where the beads can be stored indefinitely, connected to tracks where they can be moved along as needed. In the center, a junction allows the bead's path to be altered, either continuing to the side or moving downward to another section of the wafer. By combining such structures, complex series of manipulations of the beads could be carried out.

Read more at MIT News: http://web.mit.edu/newsoffice/2012/magnetic-beads-lab-on-a-chip-0925.html

Commercializing Stretchable Silicon Electronics

Thu, 05 May 2011 04:00:00 GMT

Startup company MC10 is commercializing stretchable silicon for smart surgical tools and wearable sensors. One of its first products will be a surgical tool that can quickly map and treat electrical problems in the heart.

The Best Photon Detector Yet

Tue, 08 Dec 2009 05:00:00 GMT

Mario Paniccia, director of Intel's Photonics Technology Lab, describes the company's new silicon-based avalanche photodetector and explains the technical challenges involved in making it.

Luminescent Solar Concentrators Explained

Tue, 19 May 2009 04:00:00 GMT

05/19/2009 6:00 PM MuseumMarc Baldo, Esther and Harold E. Edgerton Associate Professor of Electrical Engineering, Department of Electrical Engineering and Computer ScienceDescription: Researchers are well along in designing a highly efficient, inexpensive solar cell, but the big barrier to the dissemination of solar power in society remains the problem of installation, says Marc Baldo. As an engineer, Baldo expresses confidence that "we're going to mow down" the problem of producing a great solar cell and making it cheap. His own lab has developed a unique approach that's found enthusiastic support from the federal government and others. Unlike conventional solar cells that use a single material such as silicon to perform both functions of absorbing light and converting it into electricity, Baldo's cell "separates the functions and optimizes both." His solar concentrator utilizes inexpensive material like glass or plastic onto which a thin film of dye has been painted. Sunlight strikes this surface, and the dye, which can be "tuned" or colored to trap specific wavelengths of light, emits light back to solar cells along the edge of the plate. There are enormous advantages derived from this design: The glass or plastic (considerably cheaper than silicon) catches diffuse light, so there's no need to track the sun, and it concentrates the sunlight much more efficiently than conventional solar cells. But solar concentrators alone don't signal the start of a new solar age. Baldo addresses the considerable uncertainty around the broad deployment of solar power. Installation costs for single homes appear formidably high, perhaps 2/3rd the cost of the entire system. Colossal solar fields that might replace fossil fuel burning plants must ship their energy across vast distances, losing electricity along the way. And right now the national power grid isn't set up to handle the fluctuations in energy that large"scale intermittent energy sources such as solar or wind present. Clouds are a "big pain" for grid operators, says Baldo. He believes the best start for solar will be in commercial and industrial installations such as the rooftops of factories, supermarkets or warehouses, sites where there's no loss moving power around, and where managers are already seeking ways to save on lighting and refrigeration, including smart electronics. His cost"effective concentrators could find their way to such installations in several years. In addition to solar concentrators, Baldo is researching biological models for making solar cells more efficient: He just received a $19 million grant from the U.S. Department of Energy to study exciton circuitry in plants -- how plants capture light in packets of energy and direct the energy to where it's needed. Says Baldo, "This exciton is the last, great unexplored territory in solar cells." About the Speaker(s): Marc A. Baldo is a principal investigator in MIT's Research Laboratory of Electronics (RLE. His research interests include molecular electronics, electrical and exciton transport in organic materials, energy transfer, metal"organic contacts, heterogeneous integration of biological materials, and novel organic transistors. Baldo received his B. Eng. (Electrical Engineering) from the University of Sydney in 1995 with first class honors and university medal, and his M.A. and Ph.D. from Princeton in 1998 and 2001, respectively. In 2002 he joined MIT as an Assistant Professor of Electrical Engineering. Host(s): Office of the Provost, MIT Museum

Nanoscale Engineering for High Performance Solar Cells

Tue, 12 May 2009 04:00:00 GMT

05/12/2009 6:00 PM MuseumVladimir Bulovic, Professor of Electrical Engineering and Computer Science Description: How much energy does it take to turn on a lightbulb? Way too much in the U.S., where 22% of all electricity gets channeled into illuminating homes, businesses and thoroughfares. Vladimir Bulovic wants to end the exorbitant use of power for lighting, and simultaneously brighten our lives more pleasantly, with the application of nanostructure materials called quantum dots. Incandescent bulbs, he tells the MIT Museum audience, are hugely wasteful, with just 5% efficiency converting electricity to light. Fluorescents do the job somewhat better, and light emitting diodes better still, but these more efficient bulbs often emit colors that feel harsh to the eye. Bulovic and other researchers have been designing a fix for both the color and power conversion problems, a new kind of photo cell based on special inorganic crystals called quantum dots. The size of a human hair sliced lengthwise 5,000 times (10 nanometers), these crystals fluoresce in precise, predictable colors at different sizes: bigger chunks look red, smaller ones look blue. Bulovic has been experimenting with nanocrystal suspensions -- applying a thin film of quantum dot solution onto a surface that can be excited by shining light or by electricity. "By tuning mixtures of quantum dots, we can makeany color of the rainbow." New sorts of lights, and displays with "fantastic responsiveness" and true blacks are emerging from this research, along with power consumption half that of today's LCDs and plasma screens, and the potential of reducing energy use 20 fold down the road. Some versions of photo cells could be used in laptops, and the technology has the capacity to scale up fairly quickly. The world, well on its way to 9 billion people (many of whom still clamor for electric power), and a climate crisis, desperately needs this kind of new technology, believes Bulovic. He wonders if nanostructure materials might help with some of the hurdles engineers have encountered in scaling up solar energy solutions. For instance, the silicon used in most photovoltaics could be made more efficient by using films consisting of nanostructures that capture spectra of light that silicon can't. While solar won't solve the world's energy problems alone, it figures to be one very prominent solution, and Bulovic hopes nanotechnology will help generate energy independence, "in a controlled, clean way," helping to "uplift the world." About the Speaker(s): Vladimir Bulovic is a principal investigator in MIT's Research Laboratory of Electronics. Bulovic joined the faculty of MIT in 2000 as an Assistant Professor of Electrical Engineering and Computer Science. Prior to joining MIT, Bulovic was a Senior Scientist and Project Head of Strategic Technology Development at Universal Display Corporation (UDC). At UDC he worked on the application of organic materials to LEDs for full color flat panel displays and thin film photovoltaics for solar cell and detector applications. Prior to joining UDC he worked in Princeton's POEM Center as a graduate researcher (1993"1998) and research associate (1998"1999). Bulovic's current research interests include studies of physical properties of organic and organic/inorganic nanodot composite thin films and structures, and development of novel optoelectronic organic and hybrid nano"scale devices. In 2004, Bulovic was named as one of the TR100, the list of top young innovators in technology named annually by Technology Review magazine. In the same year, he also was awarded the Presidential Early Career Award (PECASE), the nation's highest honor for scientists and engineers at the beginning of their research careers. He graduated from Princeton University with a B.S.E. (1991), M.A. (1995), and Ph.D. (1998) in Electrical Engineering. Host(s): Office of the Provost, MIT Museum

Next Generation Solar Cells _ Lowering Costs, Improving Performance and Scale

Tue, 05 May 2009 04:00:00 GMT

05/05/2009 6:00 PM MuseumTonio Buonassisi, Assistant Professor, Laboratory for Photovoltaic ResearchDescription: According to Tonio Buonassisi, we're "on the cusp" of achieving a competitive technology for capturing the limitless energy of the sun. Buonassisi, in conversation with an MIT Museum audience, describes how, with the work of MIT and other researchers, photovoltaics may finally be coming into its own. Buonassisi describes solar cells as his "life's passion" since age 16, but scientists have been laboring somewhat longer to figure out how to convert sunlight to useful power on Earth. In 1954, Bell Labs pioneered the first solar cell. It took 12 thousand dollars' worth of these "to run an ordinary household toaster," says Buonassisi. In spite of a great leap forward in the 1990s, with breakthroughs around the purification of silicon crystals and large subsidies for national industries in Japan and Germany, solar energy today constitutes just 1% of total electric generation worldwide. The process behind solar cells appears straightforward, involving the sun's light energy (photons) exciting electrons inside some substrate; the separation of positive and negative charges; and then the collection of those charges into an external circuit. Yet scaling up this industry to compete with coal and other fossil fuels has proven daunting. Buonassisi sees several hurdles to overcome: lower materials and processing costs, improved conversion efficiencies of cells, and better manufacturing yields. He says that it takes half a square meter"sized solar panel to power a 100"watt bulb, for instance, and it would require a land area equivalent to 1/3rd the size of Nevada to convert enough sunlight to electricity for the whole U.S. In some parts of the world with intense, year"round sun, solar makes sense already, but in the cloudy, wintry northeastern U.S., huge subsidies are still required to make a go of it. Buonassisi is still optimistic: His own group removes impurities from materials that serve as wafers for solar cells, so cells can convert photons to electrons more effectively. While technological advances in photovoltaics research have not followed Moore's Law, Buonassisi believes that research can "kick off the constraint" on efficiency and performance. By the end of the next decade, photovoltaics may be "hitting some big potential markets, hundreds of millions of people." About the Speaker(s): Tonio Buonassisi runs a lab whose mission involves accelerating the adoption of photovoltaics through improvements in efficiency, cost reduction and materials utilization, among other things. At U.C. Berkeley, where he earned his Ph.D., Buonassisi explored multicrystalline silicon solar cells. He then became a crystal growth scientist at Evergreen Solar, Inc. Buonassisi has also served as a visiting scientist at the Fraunhofer Institute for Solar Energy Systems (Freiburg, Germany), and at the Max"Planck"Institute for Microstructure Physics (Halle, Germany). Buonassisi has authored or co"authored 58 articles on solar energy. He has received numerous honors, including the European Materials Research Society Young Scientist Presentation Award and the National Renewable Energy Laboratory Graduate Student Award.Host(s): Office of the Provost, MIT Museum

Manipulation of cells on microchip

Wed, 31 Oct 2007 21:01:35 GMT

Video shows E. coli cells being manipulated on a silicon chip using 'optical tweezers' to form the letters 'MIT.' Video by Lang and Appleyard, MIT. MORE