A Pulsatile Flow-Modulation Microfluidic Sensor for Simultaneous Monitoring of Red Blood Cell Aggregation and...

Area of Science:

• Biomedical Engineering
• Microfluidics
• Hemorheology

Background:

• Red blood cell (RBC) aggregation and blood viscosity are critical hemorheological parameters for diagnosing blood flow abnormalities.
• Simultaneous measurement of these parameters typically requires complex setups with multiple pumps or flow interruptions.
• Existing methods can be inefficient, consuming excessive blood and lacking real-time monitoring capabilities.

Purpose of the Study:

• To develop a simplified microfluidic sensing method using a single syringe pump for simultaneous evaluation of RBC aggregation and transient flow response.
• To enable continuous pulsatile blood delivery for real-time hemorheological monitoring.
• To establish a practical and sensitive sensor for detecting time-dependent blood changes.

Main Methods:

• A microfluidic device with a single inlet, main channel, bifurcated test channel, and outlet was designed.
• An optimized pulsatile flow profile was applied by switching between high (6 mL/h for 2 min) and low (1 mL/h for 4 min) flow rates.
• Transient velocity response was analyzed to extract the time constant (λ1) as a viscosity indicator and the RBC aggregation index (AI).

Main Results:

• The optimized pulsatile flow profile enabled stable and reproducible measurements of both λ1 and AI, reducing blood consumption.
• The extracted time constant (λ1) strongly correlated with blood viscosity and was influenced by syringe air compliance.
• The proposed AI demonstrated consistent trends with conventional indices and exhibited temporal stability under continuous flow.

Conclusions:

• The single syringe pump microfluidic method successfully achieves simultaneous evaluation of RBC aggregation and viscosity-related flow resistance.
• The developed sensor is sensitive, practical, and suitable for real-time hemorheological monitoring, including detecting changes during blood infusion.
• This approach offers a simplified and efficient alternative for assessing blood flow abnormalities.