Microfabricated in-channel structured polydimethylsiloxane microfluidic system for a lab-on-a-chip.

In this paper, the fabrication of microfluidic system integrated with micropump and microvalve on the same substrate and its high performance are described. The microfabricated microfluidic system has been optimized for application in capillary electrophoresis-electrochemical detector (CE-ECD), polymerase chain reaction (PCR) and microcantilever. The system is realized by means of a polydimethylsiloxane (PDMS)-glass chip and indium tin oxide heater. The pumping rates of the proposed micropump are measured as functions of the frequency and the duty-ratio of applied voltage. The performances of the microvalves are characterized under the on/off alternation with the applied power of the indium tin oxide (ITO) heater. The flow rate gradually decreases as the applied heater power increase. The optimized membrane thickness for microfluidic system is 350 microm. At this condition, the power of the cut-off flow in microvalve is 400 mW and the 70 nl/min of maximum pumping rate is observed at a duty ratio of 4% and a frequency of 4 Hz for the applied pulse power.

An integrated PCR microfluidic chip incorporating aseptic electrochemical cell lysis and capillary electrophoresis amperometric DNA detection for rapid and quantitative genetic analysis.

A fully integrated microchip for performing cell lysis, polymerase chain reaction (PCR) and quantitative analysis of DNA amplicons in a single step is described herein. The chip was built on glass substrate using an indium-tin-oxide (ITO) microheater and PDMS engraved microchannels, which integrated an electrochemical cell lysis zone, a continuous flow PCR module and capillary electrophoresis amperometric detection (CE-AD) system. The total length of the microchannel was 4625 mm for performing 25 cycles of flow-through PCR and was laid on a handheld form factor of 96 × 96 mm(2) area. The key to the fabrication of such a device lies in the use of a single medium to carry out different kinds of biochemical reactions and hence, a reagentless electrochemical cell lysis protocol was integrated on the microchip which was capable of lysing most cell types, including difficult to lyse gram positive bacteria. The lysate contained genomic DNA from a sample which was proven to be suitable for PCR reactions. Genetic analysis was successfully performed on the microchip with purified lambda phage genomic DNA and various cell types, including non-tumorigenic MCF-10A and tumorigenic MCF-7 human cell lines, gram negative bacteria Escherichia coli O157:H7, and gram positive bacteria Bacillus subtilis, at an optimized flow rate of 5 µl min(-1). For the detection of amplicon DNA, a CE-AD system was used, with semisolid alkaline agarose within the capillary microchannel to minimize interference from cell debris and for efficient resolution of DNA fragments. High signal to noise ratio during amperometric detection and the use of online FFT filtering protocol enhanced the limit of detection of DNA amplicons. Therefore, with a combination of portability, cost-effectiveness and performance, the proposed integrated PCR microchip can be used for one step genetic analysis of most of the cell types and will enable more accessible healthcare.