Microfluidic Reactors for Bioluminescence Detection

Bioluminescence detection is often achieved by using luciferase as an enzyme. When it is implemented in a microfluidic device, the enzyme must be properly mixed with luciferase assay reagents (LAR) to achieve enzymatic reactions. Two microfluidic reactors are investigated in this work for bioluminescence detection. The reactors were fabricated in poly(methylmethacrylate), PMMA, by hot embossing using a mold master with the reactor layouts made by high-precision micromilling. Reactor I device contains staggered herringbone mixers. Reactor II device has the same layout except that the mixers were replaced with smooth channels. We found that the mixing efficiency in Reactor I was 17.8 times higher than Reactor II. Theoretical analysis of the experimental results indicated that the required channel length of mixing was linearly proportional to the flow rate. A calibration curve for luciferase was obtained for both reactors. The limit of detection in Reactor I was determined to be 0.14 μg/mL of luciferase.

Fabrication of Micromachined Mold Masters for 3-D, High-Aspect-Ratio Cell Culturing Scaffolds

In this paper, three approaches to micromachined mold master structures for molding of a wafer-scale bone culturing platform are compared and contrasted. The processes investigated are a silicon deep-reactive ion etching (DRIE) process, an SU-8/polydimethylsiloxane(PDMS) process, and a multi-step SU-8 process. Upon comparison of the advantages and disadvantages of each approach, a wafer-scale implementation of bone cell culturing substrates is successfully demonstrated using the two-step SU-8 process, and successful duplication of hydrogels based on these molds is demonstrated.