Highly Parallel Droplet Dispensing Approach to Provide Homogeneous and Controllable Droplet Arrays for Diagnostic...

We introduce a novel approach for highly parallel droplet dispensing with precise control over the droplet parameters such as droplet volume, droplet velocity, etc. This approach facilitates the fabrication of homogeneous and precise thin layers with uniform coverage on defined small areas (e.g., a specific area of 1 × 1.4 mm² in microfluidic channels or microwells). The presented approach ensures layer uniformity and high precision in X/Y extent and edge resolution, making it well suited for achieving precise and controlled coating for a variety of applications such as homogeneous coatings for lateral flow tests, ELISA plates, and biosensors for continuous glucose monitoring (CGM) devices. Our approach is based on direct liquid displacement employing a piston that is in direct contact with the liquid and an array of nozzles. Considering a variety of nozzle chip designs (i.e., varying nozzle diameter and pitch), we evaluated a multitude of parameters to derive general design rules for the nozzle chip design. Thus, we achieved a tunable droplet volume from 200 to 800 pL and droplet velocities from 0.5 to 2.5 m/s, applying a nozzle diameter of 50 μm and a nozzle pitch of 165 μm. The presented results showcase the versatility of the approach, offering precise dispensing capabilities.