Anthony A. Grimes, Brent D. Rich, Maureen Long, Diep Nguyen and Michelle Khine
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)
Fabricating small and intricate patterns into silicon, glass, or quartz is traditionally expensive as well as manually and time intensive. These setups typically require investments in large specialized equipment, a cleanroom, and costly consumables. To translate from academic prototyping in engineering labs to truly useful analytical tools for researchers from the range of fields that "Lab on a Chip" technologies is predicted to eventually benefit, this field must mature to the point where robust and specifically designed devices can be readily realized. Ideally, researchers can conceive of a specific device design that can uniquely help investigate their hypothesis-driven investigation, and then within minutes, have in their hands a fully functional device. We have recently developed a new technique to circumvent the time and expense of conventional photolithography by leveraging the inherent shrinkage properties of the child's toy Shrinky-Dinks. Shrinky-Dinks are sheets of pre-stressed polystyrene (PS) sheets. By simply patterning these polystyrene sheets, we can create microfabricated patterns. The process we have developed is even faster than soft lithography, the commonly accepted prototyping standard for microfluidics. Furthermore, this technique obviates the high-tooling and consumable costs of photolithography altogether. Using this technique, 3D chips can even be rapidly developed directly in polystyrene (PS). In this review, we characterize the shrinkage performance of these thermoplastics and the tolerances of the patterning. While the tolerances achievable with this thermoplastic cannot yet compete with photolithography, they are sufficient for many applications. In fact, certain applications particularly benefit from the inherent channel geometries (e.g. rounded channels) that result from this approach. We demonstrate how to make and use such devices in this chapter read more ...