Fluorescence Microscopy Becomes Portable

Anne L. Fischer

A centimeter-wide “lab-on-a-chip” has been developed by engineers at the University of California, Berkeley, using a new laser-processing technique. The chip, which contains optical elements for fluorescence analysis, can be taken onto the battlefield to determine if a soldier has been exposed to biochemical agents, or it can be used on the street to identify anthrax or other toxins. It even enables DNA analysis to be performed on the spot and on the go.

The technique used to build the chip is called laser liftoff, where a laser selectively separates and transfers thin-film components from one substrate to another to build up the required layers. This process integrates a CdS thin-film filter, a thin-film InGaN blue LED and a disposable polymer microfluidic device that was placed onto the silicon photodetector. The developers see the potential for this “pixel-to-point” laser liftoff process also being employed to fabricate multicolor fluorescence-based bioassays and chemical detection microsystems.

This prototype of a fluorescence lab-on-a-chip has dual-color light sources, with two LEDs on top of silicon photodetector chips with matching thin-film filters. Courtesy of ZhongSheng Luo, University of California, Berkeley.

Tim Sands, an engineer involved with the research who is now at Purdue University in West Lafayette, Ind., indicated that the project was really about “heterogeneous integration.” The researchers from the bioengineering, electrical engineering and materials science departments had not only to learn to speak a common language and collaborate on this project, but also to find ways to combine materials that aren’t generally compatible.

Sands said the researchers have had a lot of commercial inquiries, but no specific applications are under way. They have applied for a patent through the University of California, and when it has been approved, they hope to work with people “who have something specific in mind.”

Contact: Tim Sands, Basil S. Turner professor of engineering, Purdue University Schools of Materials Engineering and of Electrical and Computer Engineering, West Lafayette, Ind.; e-mail: mailto:tsands@purdue.edu.