from: Lab-on-a-Chip Technology (Vol. 1): Fabrication and Microfluidics (Edited by: Keith E. Herold and Avraham Rasooly). Caister Academic Press, U.K. (2009)
The use of microfluidic devices is making rapid inroads in the modern analytical laboratory, primarily because of their small physical footprint, speed and efficiency of chemical separations, and reduced reagent consumption. Traditionally, lab-on-a-chip devices have been manufactured in silica due to its well understood surface chemistry and favorable micromachining techniques that are ubiquitous in the microelectronics industry. These techniques are typically based on silica etching which is time consuming, requires specialized resources, and utilizes a large amount of chemical solvents that pose unique safety and environmental hazards. Recently researchers have begun to utilize devices fabricated from polymer substrates as an alternative to glass. Reasons include reducing the total cost and the ability to tailor physical and chemical properties which may include surface roughness, surface charge, optical clarity, and tensile strength. For example, polymer substrates typically have greater impact resistance than glass and when one considers mass production, the cost of polymer substrates are a fraction of the cost of glass which leads to a large amount of savings. However, some of the advantages of using polymers are negated by the traditional microfabrication techniques used to manufacture metal or silicon molds which are subsequently utilized to fabricate polymer devices by imprinting or injection molding. The primary negative associated with manufacturing molds in the laboratory by traditional methods is the time commitment for the production of the original mold and the inability to modify the mold. This proves to be costly and time consuming. In a research and development environment it is important that researchers have access to fabrication techniques that are rapid and easily implemented with a variety of substrates. In addition it is important that changes in the fluidic circuit be implemented with minimal cost and limited time investment. Laser micromachining has been proven to be such a technique and this brief discussion describes the fabrication of simple fluidic circuits in a polymer substrate. In summary, this chapter will examine the practical details involved in laser micromachining provided from the perspective of the novice researcher who desires to utilize the technique for scribing simple microfluidic circuits in readily available polymer substrates read more ...