October 30, 2002
Cal Tech Chemical Lab On A Silicon Chip

The research group of California Institute of Technology biophysicist Stephen Quake has built a silicon chip that can function as a mini chemistry lab:

To show what such a device is capable of, Quake's team have made an array in which 3,574 microvalves can separate an injected fluid into 1,000 tiny chambers in a 25x40 grid. Each chamber contains just a quarter of a billionth of a litre of liquid. If all the chambers were full, they'd contain less than a hundredth of a raindrop. Each chamber can be individually emptied.

This is from the research paper's abstract.

Microfluidic Large-Scale Integration

Todd Thorsen,1 Sebastian J. Maerkl,1 Stephen R. Quake 2*

We developed high-density microfluidic chips that contain plumbing networks with thousands of micromechanical valves and hundreds of individually addressable chambers. These fluidic devices are analogous to electronic integrated circuits fabricated using large-scale integration. A key component of these networks is the fluidic multiplexor, which is a combinatorial array of binary valve patterns that exponentially increases the processing power of a network by allowing complex fluid manipulations with a minimal number of inputs. We used these integrated microfluidic networks to construct the microfluidic analog of a comparator array and a microfluidic memory storage device whose behavior resembles random-access memory.

The Quake group's web site at Cal Tech has all sorts of interesting information. You can read the PDF reprints of their published papers here There is a list of the group's major areas of research here. One of the projects is a miniaturized DNA sequencing device:

Novel DNA Sequencing Techniques

Marc Unger

The current paradigm in DNA sequence determination is Sanger Dideoxy sequencing by electrophoresis on polyacrylamide gels. This has limitations both in terms of speed (running a gel takes several hours) and read frame (a maximum of approximately 500 base pairs may be sequenced at one time). In order to surpass these limitations, we are developing novel a DNA sequencing technology based on microfabricated flow channels and single molecule fluorescence detection. Both microfabrication and single molecule detection have advanced to the point where straightforward techniques are readily available in the literature, and the equipment required can be purchased off-the-shelf. Work to date has focussed on microchannel preparation and calibrating our optical detection system. The picture below is a fluorescence image of single dye molecules (tetramethylrhodamine isothiocyanate) on a glass coverslip, at a magnification of approximately 1000x on your screen. Our microchannels are also working quite well - fabrication is now reliable, reproducible, and fairly easy. We are now beginning work on the chemistry of attaching molecules to the surfaces of the flow channels.

Share |      Randall Parker, 2002 October 30 12:05 AM  Biotech Advance Rates


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