Fu-Chun Huang

Integrated microfluidic systems for cell lysis, mixing/pumping and DNA amplification

The present paper reports a fully automated microfluidic system for the DNA amplification process by integrating an electroosmotic pump, an active micromixer and an on-chip temperature control system. In this DNA amplification process, the cell lysis is initially performed in a micro cell lysis reactor. Extracted DNA samples, primers and reagents are then driven electroosmotically into a mixing region where they are mixed by the active micromixer. The homogeneous mixture is then thermally cycled in a micro-PCR (polymerase chain reaction) chamber to perform DNA amplification. Experimental results show that the proposed device can successfully automate the sample pretreatment operation for DNA amplification, thereby delivering significant time and effort savings. The new microfluidic system, which facilitates cell lysis, sample driving/mixing and DNA amplification, could provide a significant contribution to ongoing efforts to miniaturize bio-analysis systems by utilizing a simple fabrication process and cheap materials.

MEMS-based Temperature Control Systems for DNA Amplification

This paper reports an innovative on-chip temperature control system using MEMS technology. Micro temperature sensors and micro heaters are integrated on glass substrates for biomedical applications. The temperature control system consists of thin-film platinum resistors as sensing/heating elements and a layer of polyimide as an isolation layer inside a micromachined chamber. It is demonstrated as a micro PCR (Polymerase Chain Reaction) chip for DNA replication. A high rise and drop rate of temperature field is attained due to low thermal inertia of the micro system. The MEMS-based on-chip temperature control system can be integrated with microfluidic structures (such as micro channels and micro chambers), which are fabricated by easy polymer casting processes. Biomedical applications such as PCR, reactors, and incubators can be realized using the developed method.

Microfluidic chips for DNA amplification, electrophoresis separation and on-line optical detection

This paper reports at innovative microfluidic chip capable of performing DNA amplification (polymerase chain reaction, PCR), electrokinetic sample injection and separation, and on-line optical detection of DNA. All microfluidic modules are integrated on cheap and biocompatible soda-lime glass substrates using a simple and reliable fabrication process. With this approach, DNA samples could be first duplicated using the micro PCR module, then injected and separated in the micro electrophoretic channels driven by electrokinetic forces, and finally detected optically by buried optical waveguides downstream the separation channel. In order to have a better separation efficiency for DNA samples, a novel surface treatment method by coating a thin layer of spin-on-glass (SOG) is developed. Experimental data show that DNA samples can be successfully duplicated using the micro PCR device with less sample and reagent volumes in a shorter period thanks to lower thermal inertia of the micro devices. DNA samples can be injected, separated and detected successfully in the subsequent microfluidic channels. The integrated microfluidic device could be crucial for genetic analysis.

Integrated Microfluidic Systems for DNA Analysis

This study reports the integration of an electrokinetically-driven micro-mixer with a on-chip temperature control system, and applies the integrated microfluidic chip to the DNA amplification process. Using the integrated chip, the cultured cells are initially broken down in a microanalysis reactor. Extracted DNA, primers and reagents are then driven electroosmotically into a mixing region where they are mixed by an electrokinetically-driven micro-mixer. The mixture is then cycled in a micro-PCR (polymerase chain reaction) chamber to perform DNA amplification. Experimental results show that the proposed device can automate the sample pretreatment operation for DNA amplification, thereby achieving significant time and effort savings. This novel integrated microfluidic device, which facilitates cell analysis, sample driving/mixing, and DNA amplification, could make a promising contribution to the continuing efforts aimed at miniaturizing bio-analysis systems

A New Self-Compensated Thermocycler for Polymerase Chain Reaction

This paper presents a new self-compensated thermocycler for polymerase chain reaction (PCR), especially used in DNA amplification process requiring precise thermal control. A new design of micro- heaters to improve the thermal uniformity of the PCR chamber using array-type heaters and a self- compensated mechanism is reported. The feature of this design is that structure change or active thermal compensation is not required. Experimental data show that the spatial variation of temperature distribution is less than ldegC in the PCR chamber at annealing temperature. Besides, the area with thermal variation less than 0.5degC is close to 90 % of the working area.

A fully-integrated microfluidic chip for RNA-virus detection

The study presents a new fully-integrated microfluidic chip capable of performing reverse transcription polymerase chain reaction (RT-PCR) (Obeid et al., 2003), transportation of DNA/RNA samples, capillary electrophoresis (CE) separation and on-line detection. In the proposed device, dengue-2 RNA-virus was synthesized to complementary DNA (cDNA) and replicated using a RT-PCR module and then transported by a pneumatic micropump to CE sample reservoir. The cDNA samples were separated electrophoretically and detected by buried optical fibers. We have successfully demonstrated the detection of a RNA-virus using less time and less consumption of samples and reagents. The developed microfluidic chip could provide a powerful tool for fast disease diagnosis.