The document discusses a centrifugal microfluidic CD platform, which is a medical diagnostic tool utilizing spinning techniques to control liquid dynamics for various applications like dengue detection and DNA purification. It outlines two types of valves: passive and active, highlighting their advantages and disadvantages in controlling liquid movement. The proposed liquid equilibrium valving method eliminates the need for external pumps, reduces contamination, and enhances control over liquid flow.

1. Novel Liquid Equilibrium Valving on
Centrifugal Microfluidic CD
Platform
MUHAMMAD ALI AIZAT BIN ABU BAKAR
BIOMEDICAL ENGINEER
6th February 2022

2. What is
Centrifugal
Microfluidic CD
platform?
 Medical diagnostic tool
 Disc-shaped platforms with networks of microchannels
and chambers
 Instead of relying on external pump, it use spinning
technique to manipulate liquid dynamics.
 The flow rate and direction can be controlled by
controlling the spinning speed of the microfluidic CD

3. Application
 Enzyme-Linked Immunosorbent Assay (ELISA) for
dengue detection
 DNA purification
 Polymerase chain reactions (PCR)
 Plasma separation

4. Material
PMMA PSA
Poly-methyl methacrylate
(Acrylic)
Polyester film resin-bonded
to aluminium oxide
Transparent, lightweight
thermoplastic
Pressure sensitive adhesive
*Depends on design

5. Typeof force
 Centrifugal force
 Capillary force
Responsible for pumping and stopping liquid flow in
microfluidic CD.

6. Typeof
parameter Centrifugal force
 Force needed to push liquid towards outer ring of CD

7. Typeof
parameter  p = density of liquid
 w = rotational speed of CD (rads-1)
 Δr = diff. btwn top and bottom liquid levels at rest,
respective to centre of CD
 r = average distance of liquid from centre of CD

8. Typeof
parameter Burst frequency
 Spinning speed of CD where the liquid will burst out of
source chamber

9. Typeof valve
Passive valve
 Valves that control liquid movement without involving
movable part
 Example: capillary valves, siphon valves
Advantages:
 No external trigger/force is required to start/stop liquid
movement
Disadvantages:
 Moderate precision in control of liquid movement on
the CD

10. Typeof valve
Active valve
 Valves that control liquid movement using external
actuations
 Example: wax valves, ice valves
Advantages:
 Sealing of liquid on the microfluidic CD during long
period of storage
 Accurate control of liquid movement on the CD
Disadvantages:
 Requires external trigger for activation

11. Structure
Source chamber
 As sample storage before
centrifugation
Destination chamber
 As sample storage after
centrifugation
Venting chamber
 To manipulate burst
frequency by increasing
liquid height in venting
chamber

12. Process
*using liquid equilibrium valve
(passive valve)

13. Process
1. Low spinning speed, below
burst frequency
 Source chamber pressure <
venting chamber pressure

14. Process
2. High spinning speed, below
burst frequency
 Source chamber pressure ->
destination chamber pressure
 Venting chamber pressure ->
destination chamber pressure
 Result: Air compression
 Source liquid -> microchannel
 Increasing destination
chamber pressure

15. Process
3. Higher spinning speed,
exceed/equal to burst
frequency
 Source chamber pressure >
venting chamber pressure
 Microchannel liquid ->
destination chamber

16. Advantage
By implementing this valving method;
 Only a compact and accurately-controlled motor is
required
 Without the need for external syringe pump
 Eliminate environmental contamination from external
pumping
 Minimize air bubbles from external pumping
mechanisms

17. Disadvantage
The permanent radial outward direction of the
centrifugal force can;
 limit the range of applicable processes
 limit complexity of applicable processes

18. Reference
 Al-Halhouli, A., Far, B. E., Albagdady, A., & Al-Faqheri, W.
(2020). Development of Active Centrifugal Pump for
Microfluidic CD Platforms. Micromachines, 11(2), 140.
https://doi.org/10.3390/mi11020140
 Al-Faqheri W, Ibrahim F, Thio TH, Arof H, Madou M. Novel
liquid equilibrium valving on centrifugal microfluidic CD
platform. Annu Int Conf IEEE Eng Med Biol Soc.
2013;2013:5509-12. doi: 10.1109/EMBC.2013.6610797.
PMID: 24110984.