1. Multi-channel Cell Counter Utilizing The Aperture Impedance Technique
Aaron Lee & Dr. Ash M. Parameswaran
Simon Fraser University
School of Engineering Sciences
Burnaby, B.C. Canada V5A 1S6
This work is sponsored by
Brain Insights, California

2. Overview Introduction Centralized approach Clinical facts
Techniques of cell counting
Electrical and physical relationships
Disposable unit design
Conclusion

3. Thesis Concentration
Construction, modeling and testing of the disposable unit and the electronics

4. Introduction Most people have blood test at some point in their lives
Blood is the vital fluid of our body and the quality of blood is an indication of health
Measured in number of cells per cubic millimeter of blood

5. Centralized approach
Most blood cell counting today is done by sending the blood samples to a centralized laboratory
Very complex system and required skilled personnel to operate
Long turn-around time
Patient has to visit another time

6. Commercial blood cell counter
18 cell sizes result and histograms
Dimensions: 37x47x38(cm)
Weight: 18 kg net
Power: AC
No portable blood counter in the market

7. Our challenges Shortens the turn around time
Reduce the cost so clinics can afford to own the blood cell counter
Miniaturize the testing equipment
Maintain or improve accuracy

8. Blood cell sizes and their normal ranges
Blood cell type
Sizes
(um)
Normal Ranges
(per mm3) --
Male
Female
Red blood cell
6-10 M M
White blood cell
10-20 k
4.5-11k
Platelets
2-4 k

9. Diseases of the Blood Cell Type Increase count Decrease count WBC RBC
Infectious diseases
Inflammatory disease
Severe emotional
Physical stress
Tissue damage
Bone marrow failure
Presence of toxic substance
Disease of the liver/spleen
Radiation
RBC
Renal tumor
Iron overload in organs
Anemia
Chronic inflammation
Platelet
Renal disease
Infection or inflammation
Uremia
Liver disease

10. Cell count techniques
Electrical
Optical

11. Electrical Counting Gain in precision and reproducibility
Lower coefficient of variation and complete a large number of determinations quickly
Cost of the electrical cell-counting equipments ($2500 to over $50,000)
Samples has to be diluted before the count

12. Constant Current Source
Impedance Principle
Constant current
Insulated chambers
Vacuum pump
Isotonic electrolytes
More on next slide
Container
Aperture
Tube with Aperture
Cell
9% NaCl Electrolyte
Vacuum Pump
Constant Current Source
Electrodes
Direction of Flow

13. Impedance Principle (Cont’d)
Aperture size is um
“Aperture size: 80 µm for commercial unit”
Measure changes in electrical resistance
Change in impedance is proportional to individual volume
Accurately counts and sizes cells

14. Capacitance Principle
Similar idea as the impedance method
Measured in the function of the change in capacitance
However, pulse amplitude generated is not proportional the cell size

15. Darkfield Optical Principle (Cont’d)
Inlet
Outlet
Darkfield stop disk
Light Source
Beam
Aperture
Photodiode

16. Darkfield Optical Principle (Cont’d)
The pulse generated by the system is not proportional to the size of the cell
Optical detection is sensitive to size of the dark field stop disk, and the optical magnification
An offset of the parameters will greatly affect the amplitude of the signal

17. Electrical and physical relationships
The pulse height-cell volume relationship can be calculated by using the Maxwell equation:

18. Resistivity of electrolyte
0.9% NaCl used as the electrolyte
Conductivity of aqueous solutions are usually expressed in Siemens
Conductivity (S/cm) =
Molarity (mol/L) x ion conductance (SL/cm/eq) x 1 eq/mol
Resistance of the 0.9% NaCl solution is calculated to be 51 Ω/cm

19. Coincidence correction
When a particle is in the aperture, and while the detecting electronics are still busy processing data, the system cannot simultaneously measure another cell

20. Design requirements
Cell sizes that we are measuring vary from 2 μm to 20 μm in diameter
Aperture size of μm in diameter will be used
Design of a disposable unit and electronics that can be put in a portable cell counter

21. Cell counter handheld unit

22. Disposable unit (1st design)
Aperture
To Vacuum

23. Disposable unit (1st design)

24. Images of Disposable unit (1st design)

25. Image of the aperture film under microscope
Drilled by laser and measured under electronic microscope
~60um

26. Conclusion
Theory of multi-channel cell counter utilizing the aperture impedance technique have been discussed
Highest resolution available in the industry for particle counting and size distribution
Color or refractive index does not affect results
More design on the disposable unit will be performed and more testing will be done

27. References
[1] Basic Principles in Biology by Y.K.To, Hung Fung Book Co.
[2] Haematology, R.B. Thompson
[3] Kubitschek HE: Counting and sizing micro-organisms with the Coulter counter, in Methods in Microbiology, ed DW Ribbons and JR Norris. London: Academic Press, 1969
[4] Coulter WH: High speed automatic blood cell counter and cell size analyzer. Presented at the National Electronics Conference, Chicago, October 1956
[5] Hayes TL: The scanning electron microscope: principles and applications in biology and medicine. Adv Biol Med Phys 12:85, 1968
[6] Brightfield and darkfield:
[7] Mansberg HP: Optical techniques of particle counting, in Advances in Automated Analysis, Vol 1. Technicon International Congress. New York: Mediad, 1969
[8] Hematology; principles and practice. Edited by Charles E. Mengel, Emil Frei, III [and] Ralph Nachman.
[9]
[10]
[11] Brecher G et al: Evaluation of an electronic red cell counter. Am J Clin Pathol 16:1439, 1956
[12] Ionic reactions and equilibria. New York : Macmillan, [1967]
[13]
[14] Practical guide to modern hematology analysers, warren Groner, Elkin Simson, john wiley and sons ltd, 1995

28. Questions