1. HORIBA Medical, Montpellier, france Damien Isèbe
Multiphysics Simulation Story: Optimizing Hematology Analysis: When Physical Prototypes Fail, Simulation Provides the Answers
HORIBA Medical, Montpellier, france
Damien Isèbe

2. The Challenge
Hematology analysis helps medical professionals make diagnosis and treatment decisions
Electrical impedance measurements are used to detect blood cell types
Hematology equipment setup includes electrodes and a microaperture leading into a counting chamber
Counting chamber design
Particle orientation and trajectory near the chamber microaperture can cause inaccurate estimates of particle size
Top: schematic of impedance measurement using hematology equipment. Bottom: voltage measurements affected by different particle orientations.

3. The Solution Use hydrodynamic focusing to reduce analysis errors
Sheath flow controls the sample travel rate inside the aperture
Direct sample flow along the central axis is possible, avoiding edge trajectories
Understand phenomena involved and determine best configuration for improving measurement accuracy with multiphysics simulation
COMSOL simulation of hydrodynamic focusing, showing how sheath flow (blue surface) directs the sample (red surface) along the central axis of the aperture.

4. The Simulation
Simulate micro aperture-electrode system using COMSOL Multiphysics®
Pressure drop
Fluid velocity
Heat transfer
Electric fields
Use results to enhance performances of impedance measurement system
Account for variation in particle trajectory and orientation
Optimize device configuration
Simulation confirmed that hydrodynamic focusing greatly improved measurement accuracy
Simulation results showing the electric field inside the aperture; T1 and T2 indicate particle trajectories along the central axis and at the edge, respectively.