Utilizing a high fundamental frequency quartz crystal resonator as a biosensor in a digital microfluidic platform

Area of Science:

• Biomedical Engineering
• Microfluidics
• Sensor Technology

Background:

• Digital microfluidic systems offer precise control over small fluid volumes.
• Quartz Crystal Microbalance (QCM) sensors provide highly sensitive mass detection.
• Integrating these technologies enables advanced biosensing platforms.

Purpose of the Study:

• To demonstrate the integration of a QCM sensor into a digital microfluidic system.
• To utilize Electro-Wetting on Dielectrics (EWOD) for actuation within the microfluidic chip.
• To validate the system's capability for detecting bio-molecule binding events.

Main Methods:

• Employing Electro-Wetting on Dielectrics (EWOD) for digital microfluidic actuation.
• Utilizing a High Fundamental Frequency (HFF; 50 MHz) quartz crystal microbalance (QCM) as a mass-sensitive sensor.
• Performing experiments involving phospholipid vesicle adsorption and protein multilayer formation (streptavidin-biotinylated IgG).
• Conducting optical macroscopic contact angle measurements for verification.

Main Results:

• Successful reversible formation of a phospholipid monolayer on a bio-functionalized QCM sensor was observed.
• Monitoring of protein multilayer formation (streptavidin and biotinylated immunoglobulin G) was achieved.
• Optical measurements confirmed bio-specific binding and its effect on surface tension.
• Demonstrated the feasibility of integrating a mass-sensitive QCM sensor into a digital microfluidic chip.

Conclusions:

• The integrated EWOD-based digital microfluidic system with a QCM sensor is a viable platform for biosensing.
• The system allows for sensitive detection and monitoring of bio-molecule interactions.
• This technology holds promise for developing advanced lab-on-a-chip devices for various applications.