Coalescence-assisted generation of single nanoliter droplets with predefined composition

Area of Science:

• Microfluidics
• Biotechnology
• Analytical Chemistry

Background:

• Accurate control over droplet composition is crucial for high-throughput screening.
• Existing methods often lack precision or require complex fabrication.
• Nanoliter-scale droplet generation presents unique challenges in controlling concentration and volume.

Purpose of the Study:

• To develop a simple, disposable, and accurate method for generating nanoliter droplets with predefined compositions.
• To enable high-resolution mixing ratios for droplet-based assays.
• To facilitate droplet-based high-throughput screening in the nanoliter volume range.

Main Methods:

• Utilizing two synchronized piezoelectric-based active droplet generators for forced droplet coalescence.
• Employing a microscope-mounted CCD camera for real-time monitoring, quantification, and fidelity assurance.
• Achieving precise control over droplet volumes and concentrations prior to merging.

Main Results:

• Demonstrated generation of highly accurate nanoliter droplets with predefined compositions.
• Achieved adjustable, high-resolution mixing ratios up to 9:1.
• Confirmed high fidelity of the droplet merging and composition control process.
• Device is disposable, surfactant-free, and simple to operate without microelectrode fabrication.

Conclusions:

• The presented platform offers a novel and efficient solution for on-demand nanoliter droplet generation with precise compositional control.
• This technology enables, for the first time, droplet-based high-throughput screening in the nanoliter range.
• The simplicity and disposability of the device make it suitable for various laboratory applications.