1
a
1,b,
2,c
2,d
3,e
1,f
1
Biomedical Nano Diagnostic Research Group , Institute of Nano Electronic Engineering, University Malaysia Perlis, 01000
Kangar, Malaysia.
2
Biotechnology Research Centre , MARDI Headquarters, Persiaran MARDI-UPM 43000 Serdang, Selangor.
3
School Of Bioprocess Engineering , University Malaysia Perlis, 01000 Kangar, Malaysia. a shzzam7@yahoo.com*, b uda@unimap.edu.my, c faridahs@mardi.gov.my, e muhammadnuraiman@yahoo.com, f d zamri@mardi.gov.my, tijjaniadam@yahoo.com
Abstract - Recently, the development of fluid delivery system results. This paper presented a design and simulation of two types such as DNA, protein, viruses or diseases and blood such as microfluidic has drawn attention among research because of its unique advantages on label-free biosensor. microchannel, micromixer, microchamber, separation, concentrator, valve and micropump. The COMSOL cell in varying concentrations.
In the biomedical analysis technology, a reagent is often
Microfluidic consists from several parts such as mixing with a target sample such as disease or biomarker in order to attract antibody or antigen. When dealing with multiphysics 4.3a engineering simulation software is a micro-scale feature, pressure will move the fluid in powerful tool and environment facilitates all steps for any separation channels unless if it involving cell separation modeling, process by defining your geometry, meshing, then both magnetic and electric force must be applied into specifying physics logic, solving and then visualizing the microfluidic in order to functioning and one common example is a separate the type of human blood cells from the microfluidic patterns and geometry by using different width as fluidic delivery system that will be used in sensing native cell. Normally, all the microfluidic separators work in laminar regime and it depends on the flow rate [7]. In domain. biosensing technology, the development of the channel
Keywords: microfluidic, separation, COMSOL multiphysic engineering simulation, geometry. length and height must be in balance.
II.
E XPERIMENTAL
I.
I NTRODUCTION
In year 1979, the very first active microfluidic system device has developed by S. Terry et al [1] which consisted of a working gas in device and has fabricated on silicon substrate. Since that, researchers began to pay attention and start working on microfluidic system because of their unique ability to deliver micron sizes cell and particle contains in fluid or gas [2] and in the early
90’s, researcher began producing a micron-sized total
In designing a pattern or model, there is basic rules need to follow such as model dimension, application mode, parameter, expression and description. The simulation will become error if any of this is not filled. Fig.1 below shows design of microfluidic with one inlet channel and three separator outlet channels in two dimension geometry, while
Fig.2 shows microfluidic after extrude to three dimensions that used in this research. The complete geometry with specific parameter has been put on the simulation. analysis system (the μTAS) [ 3] . This μTAS could perform all kinds of functions such as sample preparation, particles separation, mixing for chemical reactions and detection in an integrated microfluidic circuit for system integrated in a single chip.
Microfluidic devices provide several advantages by taking the size of microfluidic as an important factor; a faster temperature change [4], ease in applying higher electric fields [5], reduced fabrication cost and devices are easy handling [6]. Separations are an important set of applications of microfluidic devices and techniques applied for separation of cells or particles play an important role in biotechnology. Usually, these biological mixtures often consist of a wide variety cell or particle
(a)
(b)
Figure 1: (a) 2D design for 1 micron microfluidic separator, (b) 3D design for 1 micron microfluidic separator.
In other hand, microfluidic with 2 micron channels in
Fig.2 have been design in order to study effect of width
2166-0662/14 $31.00 © 2014 IEEE
DOI 10.1109/ISMS.2014.36
183

mirochannels towards pressure and fluid flow. Every parameter has a different functionality toward geometries or modals such as density (ρ), viscosity (η), diffusion constant (D), pressure drop (p and Viscosity c
2
-
0
), inlet concentration (c term prefactor (alpha (α)
0
)
. Sometimes wrong parameter could leads to error in modeling.
After meshing process is completed, result is obtained as shows Fig.4 and Fig.5 which solving and post processing completed models. Firstly, solving is a model that shows a flowing rate with concentration at the certain point as show in figure below. Red colour shows fluid at high flowing rate because it locates close to inlet of microfluidic and fluid continuing flow until at separator junction. Figure below give a full picture of this explanation.
(a)
(a)
(b)
Figure 2: (a) 2D design for 2 micron microfluidic separator, (b) 3D design for 2 micron microfluidic separator.
Afterward, next process continued with meshing.
Meshing is a process that splitting the geometry design or model into small unit and at the same time simulation program trying to computing the allowed maximum meshing element size which mean mesh element cannot be larger than minimum prescribed local element size by all mesh parameter has been set as Fig.3 shows both of geometries after meshing process.
(a)
(b)
Figure 4: (a) 1 micron microfluidic solving process after simulation, (b) 1 micron microfluidic posting process after simulation.
Meanwhile, 2 micron microfluidic shows a very same result for solving and posting process because geometry for both models is almost the same just the width of microfluidic is diverse from previous model. Figure below is the 2 micron microfluidic.
(b)
Figure 3: (a) 1 micron width of separator after meshing process, (b) 2 micron width of microfluidic
III.
R ESULT A ND
D ISCUSSION
184

(a)
Velocity field (Fig.6) that happened in 1 micron microfluidic system always seemed to be increased from
~0.5x10
-6 ms
-1
(from inlet) until to 21x10
-6 ms
-1
(reach outlet) with arc-length of the microfluidic is about 5.258
µm. Now by comparing to 2 micron microfluidic system as show below, the velocity field of system is almost proportional to the arc-length. Velocity field of 2 micron microfluidic system (Fig.7) measurement is starting from 0 ms
-1
and keep increased until 270x10
-6
ms
-1
. By comparing those two results, microfluidic with smaller width of microchannel is faster than the bigger width because smaller microchannel or microfluidic system will provide low resistant toward fluids to flowing.
(b)
Figure 5: (a) 2 micron microfluidic solving process after simulation, (b)
2 micron microfluidic posting process after simulation.
Besides that, simulation also provides important and useful information graphs such as velocity field, pressure and concentration of fluid. Velocity field is a speed of fluid or flowing rate in microfluidic system under unit ms
-1 while fluid flowing or ‘moving’, pressure is indirectly involved inside system.
Figure 7: A graph for Velocity Field, ms
-1
, starts at approximate 0.05x10
-6 ms
-1
until to maximum 270x10
-6
ms
-1
at 5.580µm arc-length.
Pressure is a one of important data in microfluidic because flowing rate of microfluidic is affected by pressure from atmosphere. Fig.8 shows result from 1 micron microfluidic and meanwhile Fig.9 shows result from 2 micron microfluidic. Both results should be directly proportional between pressure and arc-length because natural pressure cause by gravity (atmosphere pressure) is usually constant.
This matter happened when fluid flow through inside the mi crochannels, it will undergo ‘pressure drop’ because the frictional force toward the fluid that causes by a resistant to flow. Any fluids always flow in the direction of the least resistant (less pressure) in microchannels.
Figure 6: A graph for Velocity Field, ms
-1
, starts at approximate 0.5x10
-
6
ms
-1
until to maximum 21x10
-6
ms
-1
at 5.258µm arc-length.
185

IV.
S UMMARY
COMSOL Multiphysic simulation has a promising simulation application because it provides useful data or information to researcher before the real design could be transferred on the reticle or mask for fabrication process.
Simulations also make researchers able to choose the suitable geometry for the next stage of biosensor domain by according to velocity field and pressure result which very useful for designing microfluidic. Furthermore, this simulation provides low cost simulation and accuracy while working on for certain geometries. Simulation is a
A CKNOWLEDGMENT
Figure 8: A graph for 1micron Pressure, Pa, starts at 1.703 Pa and dropping until 1.698 Pa at 5.258µm arc-length.
On other hand, 2 micron microfluidic provide same graph pattern but by comparing value of in 1 micron microfluidic result, its show pressure in 2 micron microfluidic is slightly higher than pressure in 1 micron because more higher cross section any geometry, require more higher pressure in system.
The authors wish to thank Institute of Nanoelectronic
Engineering (INEE), University Malaysia Perlis and
Malaysian Agricultural Research and Development Institute
(MARDI) for giving us the financial support and opportunity to conduct this research in the Micro & Nano
Fabrication Lab and Biotechnology Lab (BT03).
Appreciation also goes to all the team members in the
Institute of Nanoelectronic Engineering especially the
Biomedical Nano Diagnostics Research Group and Biotech
Research Group.
R EFERENCES
Figure 9: A graph for 1micron Pressure, Pa, starts at 1.862 Pa and dropping until 1.770 Pa at 5.580µm arc-length.
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