Surface acoustic wave digital microfluidics with surface wettability gradient

Area of Science:

• Microfluidics
• Acoustic Wave Technology
• Surface Science

Background:

• Digital microfluidics offers precise fluid control but faces challenges in multi-droplet manipulation and positional accuracy.
• Surface acoustic waves (SAW) provide non-contact manipulation capabilities for microscale systems.
• Surface wettability gradients can influence droplet movement and localization.

Purpose of the Study:

• To develop a digital microfluidic technology integrating surface acoustic waves and wettability gradients.
• To enhance the selection of driven objects and enable sequential reactions among multiple droplets.
• To improve the positional accuracy of droplets in microfluidic systems.

Main Methods:

• Fabrication of octagonal patterns with a wetting gradient on a LiNbO3 wafer using photolithography.
• Integration of orthogonally distributed interdigital transducers for surface acoustic wave generation.
• Utilizing SAW propagation characteristics on different wetting models for microfluidic motion control.

Main Results:

• Successful selection of driven objects and demonstration of sequential reactions among multiple droplets.
• Droplets exhibited controlled movement along the wetting gradient under standing SAW excitation.
• Achieved micrometer-level positional accuracy for droplets, significantly enhancing precision.

Conclusions:

• The combined surface acoustic wave and wettability gradient digital microfluidic technology effectively addresses challenges in multi-droplet manipulation.
• This approach significantly improves droplet positional accuracy, enabling more precise microfluidic operations.
• The developed technology holds promise for advanced applications in lab-on-a-chip devices and biochemical assays.