Fluid manipulation in microfluidic devices is one of the main areas of research interest for the fabrication of Lab-On-a-Chip devices. From the many methods that have been applied to this problem, one of the most promising is employing Magnetohydrodynamic principles which allow for elegant and versatile designs. A microchip is designed for fluid flow control that uses MHD for pumping the fluid through a microchannel. Simulation of the design is performed in COMSOL and the velocity profile of the fluid is obtained. The microchip is fabricated, and experiments are performed by measuring the flow rate of a conducting fluid as it is pumped by the Lorentz force. The experimental results are then compared with the simulation results to compare the performance of the device to theoretical computations.

1. Fluid Flow Control Using
Magnetohydrodynamics (MHD)
Noorullah Rizwan 2017364 FME
Rafay Mahmood 2017378 FME
Saim ul Hassan 2017404 FEE

2. Contents
• Working Principle
• General Equations
• Components in the Channel
• Schematics & Sketches
• Project Aims and Objectives
• Design of the Channel
• Modelling on COMSOL & Simulation results
• Current Focus
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3. Working Principle
• Application of Electric and Magnetic field
perpendicular to each other.
• Lorentz force acts perpendicular to the fields.
• Velocity measurement
Source: Vaibhav Patel & Sam Kassegne (2007), Electroosmosis and thermal effects in MHD micropumps using 3D MHD Equations
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4. Lorentz Force & Navier-Stokes Equations
Source: L.. P. Aoki et al. (2013), MHD Study of Behavior of an Electrolyte Solution
using 3D Numerical Simulation and Experimental Results
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5. Components in the system
• The components include:
• Side-walled electrodes (Silver)
• Permanent magnets (Neodymium)
• Electrolyte: FeCl3 / NaCl aqueous solution
Source: Sangsoo Lim & Bumkyoo Choi (2008), A study on MHD Micropump with side-walled Electrodes 5 of 24

6. Schematics
Source: Sangsoo Lim & Bumkyoo Choi (2008), A study on MHD Micropump with side-walled Electrodes 6 of 24

7. 2D Sketch of the channel
Central Electrode Electrode Array
Source: Shizhi Qian & Haim H. Bau (2005), Magnetohydrodynamic flow of Redox Electrolyte 7 of 24

8. Project Aims and Objectives
Aim : MHD Microfluidic Flow Control
Objectives:
• Design of microfluidic chip with MHD control mechanism
• Mathematical analysis of fluid flow
• Simulations on COMSOL Multiphysics
• Fabrication of chip with electrodes
• Experimentation to compare performance with analysis and simulation results
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9. • Literature review
• Chip design / CAD model
• Equipment and material selection and ordering
• Conducted simulation of simplified model in COMSOL
• Multiple chips with channels fabricated. Currently working on
electrodes.
Progress
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10. Decide
Design Specs
Simulation on
COMSOL
Sketch Channel on
CorelDRAW
Fabricate channel on sheet
using laser engraver
Sandwich channel layer and bond
using lamination machine
Deposit electrodes on sides of
new channel with connectors
Modify
design
Does
channel
leak?
Do
electrodes
conduct?
Yes
No
No
Yes
Assemble setup with
microchip and magnet
Apply potential to
electrodes and insert fluid
Measure flow rate
of fluid
Compare
experimental
results with
simulation
Design/Development Process Flow Chart
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11. Design Specifications
Component Specifications
Channel
Length : 5-6 cm
Width : 1 mm to 3 mm
Depth : 0.150 or 0.250 mm
Channel cross-section Rectangular
Electrolyte
FeCl3 , NaCl Aqueous Solution
(0.1M – 1M)
Magnetic Field Strength 1.3T – 1.5 T
Magnetic Field Source N52 grade Neodymium Magnet
Electrode
Length : 5-6 cm
Width : TBD
Depth : TBD
Electrode Structure Central
Electrode Potential 0-30 V
Source: Specs were set after a review of papers mentioned earlier in slides 4 and 5 and then modified to our design
requirements.
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12. Initial Design of Chip / CAD Model
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13. Sketch for Laser Engraver
Channel on CorelDraw
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14. Constructed Channel
• Channel constructed
• Substrate/base material: thermal
lamination sheets
• Laser engraver used for patterning
• Thickness varies from 1 mm to 2 mm
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15. COMSOL Model
• Channel modelled on COMSOL
• Simulation with same parameters
but simplified dimensions
• Electromagnetics and Laminar flow
Multiphysics coupling.
• Open boundary conditions
• Physics controlled mesh
Constructed Model on COMSOL
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16. COMSOL Model
Top View: Direction of applied fields and force shown Front View
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17. Governing Equations for Simulation
1) Gauss’s Law for Magnetism 2) Magnetic Field Intensity in terms of Magnetic Scalar Potential
3) Constitutive Relation b/w B and H 4) B field inside Magnetic Domains
5) Remnant flux density 6) Continuity of Charge
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18. Governing Equations for Simulation
7) Current Density 8) Electric field Intensity in terms of electric scalar potential
9) Constitutive relation b/w D and E
10) Navier-Stokes Equation in Vector Form
11) Viscous forces 12) Lorentz Force
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19. Simulation Results
Cross-sectional view of the
velocity field
Streamlines of velocity field over
the entire channel
Velocity Field
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20. • Electric Potential varies linearly with
applied voltage.
Simulation Results
Velocity (m/s) vs Electric potential (V)
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21. • Electric Potential applied across the
electrodes
• Red-shade shows the +ve potential
• Blue-shade is shows the ground
• Potential falls linearly through the channel
Simulation Results
Electric Potential over the
entire channel
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22. • Design of the channel completed
• Currently focusing on electrodes
• Researched methods of electrode deposition:
• a) Electrohydrodynamic Printing
• b) Direct Ink Writing
• c) Thermal Coating
• d) Sputtering
• e) Self-designed using conductive silver paste
or conductive pen / tape.
Current Focus
Conductive Tape
Conductive silver paste
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23. Factors to be considered
• Handling of chemicals (FeCl3 can be toxic)
• Precision of the dimensions
• Channel leakage issues
• Measurement uncertainty
• Electrode corrosion
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24. Oct Nov Dec Jan Feb Mar Apr May
Literature Review
Design
Analysis
Simulation
Fabrication
Experiments
Final Report
Further Improvements
Gantt Chart
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