Young, Edmond W.K., Berthier, Erwin, Guckenberger, David J., Sackmann, Eric, Lamers, Casey, Meyvantsson, Ivar, Huttenlocher, Anna, and Beebe, David J.
Analytical Chemistry. Feb 15, 2011, Vol. 83 Issue 4, p1408, 10 p.
Rapid prototyping -- Methods, Polystyrene -- Usage, Microfluidics -- Equipment and supplies, Analytical instruments -- Production processes, and Assaying -- Equipment and supplies
Microfluidic cell-based systems have enabled the study of cellular phenomena with improved spatio temporal control of the microenvironment and at increased throughput. While poly(dimethylsiloxane) (PDMS) has emerged as the most popular material in microfluidics research, it has specific limitations that prevent microfluidic platforms from achieving their full potential. We present here a complete process, ranging from mold design to embossing and bonding, that describes the fabrication of polystyrene (PS) microfluidic devices with similar cost and time expenditures as PDMS-based devices. Emphasis was placed on creating methods that can compete with PDMS fabrication methods in terms of robustness, complexity, and time requirements. To achieve this goal, several improvements were made to remove critical bottlenecks in existing PS embossing methods. First, traditional lithographic techniques were adapted to fabricate bulk epoxy molds capable of resisting high temperatures and pressures. Second, a method was developed to emboss through-holes in a PS layer, enabling creation of large arrays of independent microfluidic systems on a single device without need to manually create access ports. Third, thermal bonding of PS layers was optimized in order to achieve quality bonding over large arrays of microsystems. The choice of materials and methods was validated for biological function in two different cell-based applications to demonstrate the versatility of our streamlined fabrication process. dx.doi.org/10.1021/ac102897h
Carrilho, Emanuel, Phillips, Scott T., Vella, Sarah J., Martinez, Andres W., and Whitesides, George M.
Analytical Chemistry. August 1, 2009, Vol. 81 Issue 15, p5990, 9 p.
Fluorescence microscopy -- Equipment and supplies and Assaying -- Equipment and supplies
This paper describes 96- and 384-microzone plates fabricated in paper as alternatives to conventional multi-well plates fabricated in molded polymers. Paper-based plates are functionally related to plastic well plates, but they offer new capabilities. For example, paper-microzone plates are thin (~180 [micro]m), require small volumes of sample (5 [micro]L per zone), and can be manufactured from inexpensive materials ($0.05 per plate). The paper-based plates are fabricated by patterning sheets of paper, using photolithography, into hydrophilic zones surrounded by hydrophobic polymeric barriers. This photolithography used an inexpensive formulation photoresist that allows rapid (~15 min) prototyping of paper-based plates. These plates are compatible with conventional microplate readers for quantitative absorbance and fluorescence measurements. The limit of detection per zone loaded for fluorescence was 125 fmol for fluorescein isothiocyanate-labeled bovine serum albumin, and this level corresponds to 0.02 the quantity of analyte per well used to achieve comparable signal-to-noise in a 96-well plastic plate (using a solution of 25 nM labeled protein). The limits of detection for absorbance on paper was aproximately 50 pmol per zone for both Coomassie Brilliant Blue and Amaranth dyes; these values were 0.4 that required for the plastic plate. Demonstration of quantitative colorimetric correlations using a scanner or camera to image the zones and to measure the intensity of color, makes it possible to conduct assays without a microplate reader.