Time-of-flight thermal flowrate sensor for lab-on-chip applications

Area of Science:

• Microfluidics
• Sensor Technology
• Thermal Analysis

Background:

• Accurate flow velocity measurement is crucial for microfluidic devices.
• Existing sensors may be limited by fluid properties and diffusion effects.

Purpose of the Study:

• To develop a thermal microflowrate sensor for accurate liquid flow velocity measurement in microfluidic channels.
• To achieve flow velocity measurements independent of liquid thermal and physical properties.

Main Methods:

• Microfabrication of a sensor with a heater and temperature detectors on silicon bridges.
• Injection of pseudo-stochastic thermal signals and cross-correlation analysis.
• Utilizing multiple detector bridges to eliminate diffusion effects.

Main Results:

• Achieved highly accurate and linear flow velocity measurements over two orders of magnitude.
• Demonstrated sensor response independent of liquid properties.
• Experimental results validated by finite element analysis and a phenomenological model.

Conclusions:

• Developed a feasible and accurate thermal microflowrate sensor for microfluidic applications.
• The sensor provides a critical component for lab-on-chip systems requiring precise flow control.
• The technology enables robust flow velocity determination irrespective of fluid characteristics.