Characterisation of medical microfluidic systems regarding fast changing flow rates using optical front tracking...

Area of Science:

• Fluid dynamics
• Microfluidics
• Optical measurement techniques

Background:

• Microfluidic systems are crucial in clinical and medical devices.
• Accurate characterization of dynamic properties in microfluidics is essential for device performance.
• Thermal flow sensors are commonly used but have limitations with dynamic flow rates.

Purpose of the Study:

• To present and validate optical flow metering methods for microfluidic systems.
• To investigate the dynamic behavior of microfluidic devices, including micro pumps and thermal flow sensors.
• To evaluate the performance of two distinct optical flow metering systems.

Main Methods:

• Utilized a Camera-System for flow rates from 50 nl/min to 500 µl/min with <4% uncertainty at 5 kS/s.
• Employed a Displacement-Sensor-System for flow rates from 100 µl/min to 50 ml/min with <3% uncertainty at 49 kS/s.
• Investigated pulsating flow rates using thermal flow sensors and analyzed signal filtering effects.

Main Results:

• The Camera-System achieved high accuracy and sample rates for microflow measurements.
• The Displacement-Sensor-System demonstrated superior performance in a broader flow range and higher sample rates.
• Pulsating flow measurements with thermal sensors showed low-pass filtering due to thermal properties, but mean flow rates were accurately determined.

Conclusions:

• Optical flow metering methods are suitable for characterizing microfluidic dynamic properties.
• Thermal flow sensors can measure pulsating flows, though signal filtering must be considered.
• The study successfully characterized the fluidic properties of different micro pump types using the developed methods.