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.
This study presents an integrated microfluidic chip capable of performing DNA/RNA (deoxyribonucleic acid/ribonucleic acid) amplification, electrokinetic sample injection and separation, and on-line optical detection of nucleic acid products in an automatic mode. In the proposed device, DNA/RNA samples are first replicated using a micromachine-based PCR module or reverse transcription PCR (RT-PCR) module and then transported by a pneumatic micropump to a sample reservoir. The samples are subsequently driven electrokinetically into a microchannel, where they are separated electrophoretically and then detected optically by a buried optical fiber. The various modules of the integrated microfluidic chip are fabricated from cheap bio-compatible materials, such as PDMS, polymethylmethacrylate, and soda-lime glass. The functionality of the proposed device is demonstrated through its successful application to the DNA-based bacterial detection of Streptococcus pneumoniae and the RNA-based detection of Dengue-2 virus. It is shown that the low thermal inertia of the PCR/RT-PCR modules reduces the sample and reagent consumption and shortens the reaction time. With less human intervention, the subsequent DNA separation and detection could be performed in an automatic mode. The integrated microfluidic device proposed in this study represents a crucial contribution to the fields of molecular biology, genetic analysis, infectious disease detection, and other biomedical applications.
This paper presents an innovative portable chip-based RT–PCR system for amplification of specific nucleic acid and detection of RNA-based viruses. The miniature RT–PCR chip is fabricated using MEMS (Micro-electro-mechanical-system) techniques, and comprises a micro temperature control module and a PDMS (polydimethylsiloxane)-based microfluidic control module. The heating and sensing elements of temperature control module are both made of platinum and are located within the reaction chambers in order to generate a rapid and uniform thermal cycling. The microfluidic control module is capable of automating testing process with minimum human intervention. In this paper, the proposed miniature RT–PCR system is used to amplify and detect two RNA-based viruses, namely dengue virus type-2 and enterovirus 71 (EV 71). The experimental data confirm the ability of the system to perform a two-step RT–PCR process. The developed miniature system provides a crucial tool for the diagnosis of RNA-based viruses.
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 microheaters to improve the thermal uniformity of the PCR chamber using array-type heaters and a selfcompensated 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 1°C in the PCR chamber at annealing temperature. Besides, the area with thermal variation less than 0.5°C is close to 90% of the working area.
The paper reports two platforms for fast diagnosis of infectious diseases using enabling Bio-MEMS (Bio-Micro-Electro-Mechanical-Systems) technology. The first platform uses molecular biology techniques for DNA-based diagnosis. An integrated microfluidic chip capable of performing DNA/RNA amplification, electrokinetic sample injection and
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