Scanning Laser Produces 3-D Microstructures

Daniel S. Burgess

A team of engineers at Fraunhofer USA Center for Manufacturing Innovation and at the department of manufacturing engineering at Boston University, both in Boston, has reported the rapid fabrication of microfluidic structures using a scanning laser system. The three-dimensional approach has potential applications in the production of microfluidic components for the biology and biotechnology sectors.

The scanning laser system fabricated a functional microfluidic component, featuring a microvalve attached to a 3000-µm-long cantilevered beam. Courtesy of Biao Li, Fraunhofer USA Center for Manufacturing Innovation.

In the technique, a diode-pumped, nanosecond-pulse-duration Nd:YAG laser operating at a wavelength of 355 nm exposes a copolymer and a photo acid generator through a two-axis scan head and an expander lens. The system produces a nonuniform distribution of laser power along its incident axis. The engineers thus achieve both in-plane and out-of-plane processing by controlling the current to the pump diodes and/or by varying the focus level to yield the desired exposure energy from the Nd:YAG laser at the appropriate spot in the photoresist.

To demonstrate the approach, the researchers fabricated various microstructures, including convex and concave microlenses and an array of cantilevered beams. They also manufactured a functional component, featuring a microvalve attached to a 3000-µm-long cantilevered beam. Tests of the valve indicated that it could control the flow through an embedded fluidic channel.