Lab-on-a-chip takes aim at bettering beer, fine-tuning processes
04/01/2003
By Mark A. DeSorbo
MUNICH—Microchips will never be a choice snack with a pint of ale, but the combination could make "bitter beer face" an annoyance of the past and environmental monitoring even more acute if a Siemens AG microfluidic system—a lab-on-a-chip—proves effective in its initial testing.
The tiny, five-centimeter-wide chip contains microscopic tubes—as thin as 50 to 100 micrometers—that sample fluids and transmit electrical currents that relay concentration analyses of metal ions, organics and proteins.
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While the system is tested at undisclosed breweries, researchers at the microelectronics developer continue to modify its capillary electrophoresis-derived lab-on-a-chip for use in environmental monitoring technology as well as biotechnology and pharmaceutical processes, says chemist Norbert Aschenbrenner, a Siemens spokesperson.
"Right now, you can use it for all fluids, as it can detect all sorts of metal ions, organic molecules and proteins," Aschenbrenner says. "We are developing prototypes for environmental protection and for pharmaceutical and biotechnology application. The prototypes we have now are being used in breweries first because [Siemens] thought they would be the first customers to use it."
The microfluidic system, he says, is integrated into a production process, like those in a brewery. Unlike previous analytic devices, it delivers data continually; a method that had previously been unavailable to food and beverage processors.
Lab-on-a-chip technology, which uses semiconductor-making techniques to build interconnected fluid reservoirs and pathways, is widely used by life science industries, namely for cell assays in DNA analysis.
The tiny tubes, or channels, are the key component of the lab-on-a-chip, enabling it to perform analyses in a short period of time. In fact, results are ready in as fast as three minutes.
Depending on the composition, samples may require between 10 minutes and one hour to complete an analysis, according to researchers. The mode of operation is based on the premise that the dissolved substances contained in the fluid move at different speeds through a capillary tube under the influence of an electric field and, therefore, arrive separately at the end of the measured section.
A detector tracks particles, while software calculates the percentage of each substance in the fluid. Such devices have previously only been available for laboratory procedures.
Before, Aschenbrenner says, quality control at a brewery involved taking frequent samples manually for analysis. "If the beer is finished, there will be certain chemicals present, and the channels within the device will do the separations, so you can tell exactly when the brewing process is finished," he adds.
The chip can also find a home in a brewery's bottle cleaning process, where it can be used to continually detect contamination and calibrate water-to-cleaning agent ratios.
Siemens is also working on applying this technology to the continual monitoring of industrial processes.
In cooperation with the Institute for Spectrochemistry and Applied Spectroscopy (ISAS; Dortmund), specialists in Karlsruhe have developed a microfluidic system that consists of tubes as thin as a human hair.
Test fluid is dripped into the system at a rate of about one microliter per minute, with only a few nanoliters of the test fluid being diverted by an electrical current into the separation channels of the system. The new device, presently undergoing tests for its effectiveness, can analyze several components of a given liquid sample in accordance with specific requirements.