Study and evaluation of a PCB-MEMS liquid microflow sensor.

Area of Science:

• Microfluidics
• Sensor Technology
• Printed Circuit Board (PCB) Integration

Background:

• Accurate measurement of low liquid flow rates is crucial in various scientific and industrial applications.
• Existing microflow sensors often face challenges with integration, thermal management, and sensitivity at low flow volumes.
• Printed circuit board (PCB) integration offers a pathway for miniaturization and cost-effective sensor fabrication.

Purpose of the Study:

• To evaluate a novel miniature liquid microflow sensor directly integrated onto a PCB.
• To investigate the sensor's performance based on the convective heat transfer principle.
• To optimize sensor design and housing for enhanced sensitivity and a wide measurement range.

Main Methods:

• The sensor utilizes thin Platinum (Pt) resistors as heating and sensing elements, directly connected to PCB copper tracks.
• Leveraging the low thermal conductivity of the substrate material for improved thermal isolation and sensor performance.
• Employing multiple sensing elements at varying distances from the heater to exploit liquid temperature distribution.
• Developing a specialized housing for seamless integration into tubes of diverse cross-sectional areas.

Main Results:

• The sensor demonstrated dual-mode operation, functioning under both hot-wire and calorimetric principles.
• Quantified sensor sensitivity and measurement range were directly correlated with sensing element distance from the heater.
• Achieved a high degree of thermal isolation, enhancing overall device operating characteristics.
• Established a minimum resolution of 3 μL/min and a maximum measurement flow range of up to 500 μL/min.

Conclusions:

• The PCB-integrated miniature liquid microflow sensor offers a promising solution for precise low-flow measurements.
• The convective heat transfer principle, combined with strategic element placement and thermal isolation, enables high performance.
• The developed sensor and housing facilitate versatile implementation across various microfluidic systems.
• This technology advances the field of microflow sensing with its compact design and robust measurement capabilities.