Multi channel cell counter utilizing the aperture impedance technique
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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 Email: [email protected] This work is sponsored by Brain Insights, California Overview Introduction

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Multi channel cell counter utilizing the aperture impedance technique l.jpg

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

Email: [email protected]

This work is sponsored by

Brain Insights, California


Overview l.jpg
Overview Technique

  • Introduction

  • Centralized approach

  • Clinical facts

  • Techniques of cell counting

  • Electrical and physical relationships

  • Disposable unit design

  • Conclusion


Thesis concentration l.jpg
Thesis Concentration Technique

Construction, modeling and testing of the disposable unit and the electronics


Introduction l.jpg
Introduction Technique

  • 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


Centralized approach l.jpg
Centralized approach Technique

  • 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


Commercial blood cell counter l.jpg

18 cell sizes result and histograms Technique

Dimensions: 37x47x38(cm)

Weight: 18 kg net

Power: AC

No portable blood counter in the market

Commercial blood cell counter


Our challenges l.jpg
Our challenges Technique

  • 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




Cell count techniques l.jpg
Cell count techniques Technique

  • Electrical

  • Optical


Electrical counting l.jpg
Electrical Counting Technique

  • 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


Impedance principle l.jpg

Constant Current Source Technique

Vacuum Pump

Electrodes

9% NaCl Electrolyte

Aperture

Tube with Aperture

Cell

Direction of Flow

Container

Impedance Principle

  • Constant current

  • Insulated chambers

  • Vacuum pump

  • Isotonic electrolytes

  • More on next slide


Impedance principle cont d l.jpg

Aperture size is 50-100um Technique

“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

Impedance Principle (Cont’d)


Capacitance principle l.jpg
Capacitance Principle Technique

  • 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


Darkfield optical principle cont d l.jpg

Outlet Technique

Light Source

Beam

Aperture

Photodiode

Darkfield stop disk

Inlet

Darkfield Optical Principle (Cont’d)


Darkfield optical principle cont d16 l.jpg
Darkfield Optical Principle (Cont’d) Technique

  • 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


Electrical and physical relationships l.jpg
Electrical and physical relationships Technique

  • The pulse height-cell volume relationship can be calculated by using the Maxwell equation:


Resistivity of electrolyte l.jpg
Resistivity of electrolyte Technique

  • 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


Coincidence correction l.jpg
Coincidence correction Technique

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


Design requirements l.jpg
Design requirements Technique

  • Cell sizes that we are measuring vary from 2 μm to 20 μm in diameter

  • Aperture size of 50-100 μm in diameter will be used

  • Design of a disposable unit and electronics that can be put in a portable cell counter



Disposable unit 1 st design l.jpg
Disposable unit (1 Techniquest design)

Aperture

To Vacuum


Disposable unit 1 st design23 l.jpg
Disposable unit (1 Techniquest design)


Images of disposable unit 1 st design l.jpg
Images of Disposable unit (1 Techniquest design)


Image of the aperture film under microscope l.jpg
Image of the aperture film under microscope Technique

Drilled by laser and measured under electronic microscope

~60um


Conclusion l.jpg
Conclusion Technique

  • 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


References l.jpg
References Technique

  • [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: http://www.wsu.edu/~omoto/papers/Fig1.html

  • [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] http://www.principalhealthnews.com/topic/topic100587682

  • [10] http://www.utmem.edu/physpharm/.010.html

  • [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] http://www.colby.edu/chemistry/CH141B/CH141B.Lab/CH141L4condFall2002.pdf

  • [14] Practical guide to modern hematology analysers, warren Groner, Elkin Simson, john wiley and sons ltd, 1995


Questions l.jpg
Questions Technique


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