CELL-DYN 3700: Principles of Operation

Sample Aspiration

There is 2 modes of aspiration.

• Open Sampler Mode is used to aspirate sample from a collection tube that has been opened and is held under the Open Sample Aspiration Probe.
• Manual Closed Sampler Mode or Automated Sample LoaderMode aspirate blood directly from a capped collection tube by piercing the tube stopper.

Aspiration volume for open mode is 130uL ± 5%, 240uL ± 5% for close mode, and 355uL ± 5% for Sample Loader mode. Sample is aspirated into the Analyzer by the Aspiration Peristaltic Pump, through the Shear Valve.

White Blood Cells(WBC) Analysis

2 measurements: WBC optical count (WOC) and WBC impedance count (WIC).

1. WOC Sheath Syringe dispenses 1.6mL of Sheath Reagent through the Shear Valve, picking up 32uL sample.
2. Sample segment and sheath are then routed to WOC mixing chamber where dilution is bubble-mixed. (1:51)
3. WOC Peristaltic Pump transfers the WOC dilution from the WOC Mixing Chamber to Sample Feed Nozzle in WOC flow cell.
4. A stream of WOC Sheath Reagent is directed through the Flow Cell.
5. WOC Metering Syringe injects 78uL of WOC dilution into the Flow Cellsheath stream.
6. A laser beam is focused on the Flow Cell. As the sample stream intersects the laser beam, the light scattered by the cells is measured at four different angular intervals.

1. WIC/HGB Diluent Syringe dispense 5.25mL of Diluent through Shear Valve, picking up the 20uL WIC/HGB sample segment.
2. Segment and Diluent fouted to Mixing Chamber in the von Beherns WIC Transducer. At the same time, WIC/HGB Lyse Syringe delivers 0.75mL of WIC/HGB Lyse to mixing chamber.
3. The dilution is bubble-mixed. Final dilution is 1:301.
4. Dilution is pulled through the aperture by vacuum, Volumetric metering ensures 200uL used for measurement.
5. Electrical Impedance is used to count WBC as the traverse the aperture.
6. When the count portion of the cycle is completed, the aperture is auto-cleaned by Aperture cleaning circuit.

RBC/PLT Analysis

1. RBC Diluent Syringe dispenses 7.2mL diluent through Shear Valve, picking up 0.74uL RBC/PLT sample segment
2. Sample segment and diluent routed to mixing chamber of von Behrens RBC/PLT Transducer where dilution is bubble-mixed. (1:9760)
3. Dilution is pulled through the aperture by vacuum. Volumetric metering ensures that 100uL of dilution is measured.
4. Electrical Impedance is used to count RBCs and PLTs as they traverse the aperture.

Haemoglobin Analysis

1. After 200uL of WIC /HBG are metered through WIC aperture, remaining dilution is transferred to HGB Flow Cell.
2. HGB concentration is measured spectrophotometrically.

*All information obatined from ABBOTT CELL-DYN 3700 operator's manual.

Cheers
Douglas