Precise loading of scarce reagents on droplet microarrays

Area of Science:

• Biotechnology
• Chemical Engineering
• Microfluidics

Background:

• Experiments often require expensive or limited reagents and biological samples.
• Droplet microarrays offer a solution for conserving materials through parallelized reactions in small volumes.
• Current droplet microarray loading methods face challenges with consistency and significant dead volumes.

Purpose of the Study:

• To present the Small Volume Loader (SVL) for the Surface Patterned Omniphobic Tiles (SPOTs) platform.
• To enable precise deposition on droplet microarrays while minimizing reagent waste.
• To overcome limitations of existing loading methods.

Main Methods:

• Developed a physical model of the droplet loading process, identifying pressure dynamics.
• Engineered a pressure-compensating flared reservoir geometry for consistent deposition.
• Reduced dead volume to 5 μL through optimized design.

Main Results:

• The SVL ensures deposited volume is independent of reservoir volume.
• Demonstrated high-throughput elicitor screening for antimicrobial production from *Streptomyces venezuelae*.
• Assays used 100-fold less material than conventional methods, enabling over 32,000 assays.

Conclusions:

• The SVL platform provides precise and accessible high-throughput assays.
• Minimal reagent volumes are sufficient for complex screening.
• Enabled identification of stressors optimizing antibiotic production (chloramphenicol, jadomycin B).