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California State University, Long Beach
 

Chemical Engineering (ChE)

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Dr. Roger C. Lo

Graduate Advisor
Assistant Professor

Spring 2014 Schedule

Schedule Sem/Lab Time Days Room
CHE 440 LAB 9:00AM-11:45AM MW ECS-114

Profile:

Roger C. Lo received his B.S. from National Chung Hsing University in Taiwan in 1997 and M.E. and Ph.D. from Texas A&M University in 2002 and 2008, respectively, all in chemical engineering. Dr. Lo’s research interest focuses on developing microfluidics-based systems for high-throughput separation and detection of chemical/biological species, and modular chemical/biological reactions. His research projects are as follows:

Fluorescence-Based Detection System

In his Ph.D. work, Dr. Lo designed and built a new automated whole-gel scanning detection system (including an optical microscope, CCD camera, a power supply, and an programmable precision X-Y translation stage) to enable rapid and detailed characterization of DNA gel electrophoresis on a microfluidic device based on fluorescence imaging (Figure 1). To expand the capability of this design, his research group will create new multi-channel chips and to include new detection schemes in order to perform multiplex, multiple-color detection of chemical and biological molecules based on fluorescence imaging.

Label-Free UV Imaging Detection System

Dr. Lo’s research group currently works on the development of a novel label-free detection system based on UV imaging. Current fluorescence-based detection techniques require the fluorescence signal generated by the target molecules themselves or the fluorescent tags attached to them. However, there are adverse effects by the introduction of fluorescent tags. First, the detection is limited to self-fluorescent molecules if no fluorescent tags are needed. Second, the additional step to attach fluorescent tags to non-fluorescent molecules is not always straightforward, and it alters the structure of the target molecules, which can cause significant property changes of the target molecules, especially for biomolecules. UV absorbance has been widely used in benchtop chromatography and capillary electrophoresis systems, but there are very few reports for UV absorbance detection on microfluidic chips. This is because the small channel dimensions post serious problems in sensitivity and reliability of absorbance measurements due to a very short optical pathlength (usually tens of microns in channel depth). To address this problem, Dr. Lo’s group will construct new microfluidic chips with high aspect-ratio microchannels (up to 1 mm in depth) using a new microfabrication technique and commercially available adhesives. These new chips, coupled with a UV area imager, will allow us to perform direct, high-throughput detection of chemical/biological molecules without the need of fluorescence signal from the target molecules.

Modular Microreactor Technology

Microreactor technology has received great attention from many research groups and companies because of its advantages over conventional macroscale reactors, e.g., safety, lower reagent consumption, lower waste emission, and better control on mass and heat transfer. Dr. Lo recently built a simple PDMS microreactor with an embedded permanent magnet holding enzyme-coated magnetic beads and successfully performed an aqueous enzymatic reaction (Figure 2) for proof of concept. Dr. Lo’s group will work on the development of “plug-and-play” microfluidic chips for various chemical/biological reactions, e.g., solvent-resistant chips for organic synthesis and chips packed with surface-modified microbeads for enzymatic reactions. Based on the concept of unit operations in chemical engineering, they will use these new modular chips to build highly customizable microreactors, which can be used to quickly screen optimal reaction conditions with a combination of only a few modular chips or to mass produce the desired compounds with a combination of tens or hundreds of these chips, depending on the scale needed.

Figure 1. Whole-gel scanning detection based on fluorescence imaging. The scanning method employs a detector that can traverse the separation channel so that it can be continuously images. This allows the entire DNA separation process to be observed as it unfolds in time.

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Figure 2. (a) A microreactor with magnetic beads packed in the PDMS microchannel. The rare earth (neodymium-iron-boron, NdFeB) magnet was embedded in the chip on top of the microchannel during fabrication. The cross section dimensions of the channel are 160 µm wide and 75 µm deep, respectively. The magnetic beads were loaded into the microchannel by a peristaltic pump for packing; (b) Enzymatic reaction on a PDMS microreactor.

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