Abstract:
A microfluidic device is an apparatus that has dimension in micrometer or nanometer.
There are several benefits of the microfluidic device, for example, small amount of
reagent is used and less waste is generated. It can be integrated many different functions
onto one chip called lap-on-a-chip (LOC). Due to its advantages, it had been studied
developed since 1990s. Nowadays, the requirement in utilizing of a microfluidic device
has increased. Therefore, aim of this work is to develop a simple prototyping
technology for a microfluidic device. The device was fabricated from
polymethylmethacrylate or PMMA using hot embossing method. There were 2 patterns
of microhannel, straight and branch. A design depth of both types of microcahnnel was
200 Jlm. The PMMA sheets with thickness of2-mm and 3-mm were applied to produce
the microchannel using brass master. Fabrication of the microchannel was carried out at
120?C with 6 values of compressive pressure, 3 MPa, 4.5 MPa, 6 MPa, 7.5 MPa, 9
MPa and 10.5 MPa. It was figured out that the higher compressive pressure leaded to
the greater deep of microchannel. The depth of the embossed microchannel of 3-mm
thick was slightly larger than the depth of the embossed microchannel of 2- mm thick.
A maximum difference between those 2 thicknesses was only 11.4 Jlm which was not a
significant difference. Therefore, 2-mm thick ofPMMA sheet was more preferable than
3-mm thick of PMMA sheet because its price is cheaper than 3-mm thick of PMMA
sheet. Moreover, when technical point of view is considered, 2- mm thick of PMMA
sheet is easier cut than 3-mm thick of PMMA sheet. At the compressive pressure of
10.5 MPa, the depth of the microchannel was approximately 200 Jlm which was the
closest as designed. The surface of embossed microchannel could be assumed that it
was smooth as roughness of the embossed microchannel was only 1.2697 Jlm. Moreover,
the surfaces of PMMA sheets were treated by oxygen plasma and stored under 2
conditions, air and water. Although oxygen plasma could improve the surface of
PMMA, however, it was found that hydrophobic recovery was 240 hr after performing
oxygen plasma. There was no important difference between keeping in air and water.
The microfluidic devices were successfully sealed by a mixture of of 1,2-dichloroethane
and ethanol with a ratio of 30:70 percent by weight. To demonstrate performance of the
produced device, injection of 2 different colors liquid into branch microcahnnel was
performed and confirmed that flow in microchannel was laminar.