Enhanced Quality Factor Label-free Biosensing with Micro-Cantilevers Integrated into Microfluidic Systems.

Area of Science:

• Sensor Technology
• Microfluidics
• Biotechnology

Background:

• Microelectromechanical systems (MEMS) sensors offer advanced capabilities but face performance degradation in liquid environments.
• Viscous drag and the need for capture molecules limit acoustic sensor operation in native biomolecule solutions.
• Existing MEMS sensor platforms require specific surface modifications for analyte binding.

Purpose of the Study:

• To develop a novel strategy for interfacing MEMS sensors with microfluidic platforms using aerosol spray.
• To overcome the limitations of MEMS sensor operation in liquid, such as viscous drag and analyte binding.
• To demonstrate a label-free, high-sensitivity sensing method for analytes in solution.

Main Methods:

• Integration of a microfluidic spray nozzle with a microcantilever array operated in dynamic mode.
• Utilizing a closed-loop oscillator for real-time monitoring of microcantilever frequency shifts.
• Applying a picoliter droplet aerosol spray to deposit analytes onto the microcantilever surface, followed by rapid evaporation.

Main Results:

• Achieved a 50-fold increase in the quality factor compared to liquid-based operation.
• Demonstrated a 370 femtogram limit of detection for analytes.
• Successfully performed quantitative, label-free analysis of inorganic salts and model proteins.

Conclusions:

• The integration of spray microfluidics with MEMS sensors overcomes standard resolution limits.
• This approach enables sensitive analyte detection from solution without direct surface functionalization.
• The developed platform offers a promising route for advanced biosensing applications in native liquid environments.