New Micromachining Method Upgrades Microfluidic Chip Technology

April 1, 2009

Someday, you may be able to go to your neighborhood drugstore and choose from a diagnostic kit that can test for high cholesterol, a faulty gene that predisposes you to diabetes, or a staph infection. The automation and miniaturization of laboratory functions have undergone a steady evolution of improvements. These changes have enabled researchers to dig more deeply into biology, shorten assay times for pharmaceutical testing, and even take some items from the doctor’s office to the open shelves of the drugstore.

Translume of Ann Arbor, MI, with the help of a Phase I Small Business Technology Transfer (STTR) grant from the Missile Defense Agency (MDA), investigated the use of femtosecond lasers for maskless etching of glass materials and micromachining of optical structures. Translume brings both improved materials and manufacturing to microfluidic chips for biological and chemical testing. Such chips contain tiny channels that route reagents and reactants in sequence, replacing the researcher mixing chemicals at the bench for needs as diverse as antibody testing and DNA hybridization.

How it Works

Previously, labs on chips were simple wells in which nanoliters to microliters of sample were used to carry out various reactions of interest. Today’s more sophisticated chips use microfluidic channels, which with their very small dimensions, add some advantages to the dynamics of chemical reactions by adding what is essentially a plumbing system to route and direct reactants. As labs on a chip become more accepted in the consumer market and physicians let go of the diagnostic monopoly, pharmacies and other stores could sell inexpensive test kits to consumers. Quicker diagnosis also would be welcomed by physicians and patients alike.

Most commercial microfluidic chips are wet-etched in silicon (chemically), a method that results in trapezoidal or rectangular cross-sections with large, rounded corners. These shapes are not suited to the chemistry desired by its users. Translume addresses these shortcomings with its direct laser etching methods that produce deep channels with nearly vertical walls. In addition, Translume’s chips are made of fused silicate, making them ideal for tests like fluorescence in situ hybridization (FISH), in which fluorescent markers are used to mark genes on stretches of DNA.

Many materials possess natural fluorescence, or fluoresce in response to ultraviolet (UV) light, creating false signals. Fused silica does not auto-fluoresce and is transparent to UV. Its additional advantages are longevity and ruggedness, and it lasts well beyond the lifetime of the experimenter (centuries). The material has a hardness of 6.5 on the Mohs scale, slightly below that of quartz, and is highly resistant to scratches, making it ideal for robotic applications in which the chips are handled repeatedly, or for the dirtier conditions of field work.

Translume has developed four femtosecond-laser-based fabrication processes to fabricate and commercialize fused silica devices, including its microfluidic chips: femtoTrim™, femtoWeld™, femtoEtch™, and femtoWrite™. The company uses the femtoWrite process to produce deep three-dimensional microchannels with sharp-shaped features that are unavailable using traditional mask and etching techniques. The reactions as conducted in these chips are roughly ten times faster than conventional lab-on-a-chip offerings, owing to factors such as small reaction volumes and the relative distances traveled by the reagents as they travel through the microfluidic channels.

Where it Stands

The combination of the laser technology, robust materials, and Translume’s manufacturing approach allow the company to offer the new chips at a cost advantage. The company also plans an expansion of this line to include micro-reactors, flow cytometers, and capillary electrophoresis modules, which are used in the pharmaceutical and biotech industries.

The process of developing three-dimensional glass microstructures is termed GMEMS™ (Glass Micro Electro Mechanical Systems). The technology is useful in many other areas, such as the creation of micron-scale optical waveguides that can move or flex. Thus, Translume has much to offer in the optical communications area, as well as general manufacturing of materials requiring precision etching or drilling.

Translume is working with the Michigan Economic Development Corporation to further develop its market. In addition, the company is using some of its original venture capital funding to improve its production line.

More Information

For more information on Translume’s manufacturing process, click here . (Source: Joan Zimmermann/NTTC; MDA TechUpdate, Missile Defense Agency, National Technology Transfer Center Washington Operations)

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