Team Members:

Dr. Jim Zoval
Mr. Guangyao Jia
Mr. Jitae Kim
Mr. Joshua Kim
Mr. Chengwu Deng

Research Summary:

1. Microfluidics background:

In general, microfluidics refers to the study of conduits for fluids that have a smallest design feature on the scale of a micron or larger. In practice, this often means rectangular channels with cross-sectional dimensions on the order of tens or hundreds of microns [1]. Extensive research on microfluidic devices has been conducted in the past ten years and the vast majority of the work has been directed toward the biomedical and life sciences. However, most of the devices developed so far are limited to single-purpose applications (e.g., sample preparation, detection, amplification, etc) because of the difficulty of integrating several analytical functions all onto one fluidic platform. Highly modular automated analysis systems are becoming a necessity in real life. 

2. CD microfluidics:

Compact disc (CD) Microfluidic platform is a promising approach for the integration of multiple functions on the same substrate. On the CD platform, centripetal force is utilized as a driving force for sample and reagent propulsion. Surface tension elegantly provides for a value less gating of the flows. The wide range of spin speeds and the flexible design of the microstructures on a plastic disc afford the integration of various analytical functions. Example analytical functions that have been successfully implemented are: sample metering, sample splitting, separation of serum from whole blood, two-point-optimal sensor calibration (figure 1), cell lysis, immuno-assays, etc. Combining sample preparation such as DNA extraction, and purification from cells, DNA amplification and DNA hybridization arrays. 

Figure1 Two-point calibration microfluidic platform

3. Recent Results:The objective of this project is total molecular diagnostics on an CD. 

Example:  

  Figure 2 Spin stand equipped with CCD camera

  
A CD for mechanical cell lysis was fabricated using SU-8 photolithography and PDMS molding and tested on an in-house designed spin stand (see figure 2). The cell sample (CHO-K1) and micro glass beads were loaded into the lysis chamber of the CD platform, and rapid back and forth spinning generates shear and inter-bead collisions that efficiently disrupt the cells. As shown in Figure 3, microscope photo showed that almost all the cells were disrupted. 

Cells and glass beads – before spinning (100X)

Cells and glass beads – after spinning (100X)

Figure 3 Comparison of sample cells before and after spinning

 
References:

[1] H.A., Stone, S. Kim, “Microfluidics: Basic issues, applications, and challenges”, AICHE J 47 (6): 1250-1254 Jun 2001

[2] M.J., Madou, L.J. Lee, S. Daunert, S. Lai , C.H. Shih, “Design and fabrication of CD-like microfluidic platforms for diagnostics: microfluidic functions”, biomedical microdevices, vol 3, no. 3, 245-254

[3] G.J. Kellogg, T.E. Arnold, B.L. Carvalho, D.C. Duffy, N.F. Sheppard, “Centrifugal Microfluidics: Applications”. Micro Total Analysis Systems 2000, A. van den Berg, W. Olthuis, P. Bergveld, Kluwer Academic Publishers, 2000 pp. 239-242