Co-planar light-actuated optoelectrowetting microfluidic device for droplet manipulation

Jodi Loo,Shao Ning Pei,Ming C Wu

doi:10.1117/1.jom.1.3.034001

Jodi Loo, Shao Ning Pei + Show 1 more

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https://doi.org/10.1117/1.jom.1.3.034001

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Abstract

We report on a co-planar light-actuated digital microfluidics device that features a metal mesh grid integrated on the device surface to allow droplets to be exposed from above. We discuss a theoretical circuit model for our co-planar optoelectrowetting (OEW) design that allows for the optimization of droplet actuation while maintaining reliable droplet movement. Basic droplet manipulations such as merging and parallel actuation of droplets are achieved at speeds of up to 4.5 cm / s. The co-planar OEW device design benefits from having an open top design that allows for a wider range of system integration configurations than previous generations of OEW devices. A droplet-on-demand dispensing system from above is integrated with the co-planar OEW device to demonstrate the versatility of this optofluidic platform. The ability to inject, collect, and position individual droplets to form large-scale droplet arrays of up to 20 × 20 is achieved.

Highlights

Droplet-based digital microfluidics addresses many requirements for lab-on-a-chip systems through the ability to process a large number of samples using reduced sample and reagent volumes while increasing detection sensitivity
Droplet speed is used as a figure of merit to compare to force since the net force to move a droplet is a balance between the frictional forces and the actuation force generated by OEW.[39]
Demonstrations of fabricated co-planar OEW devices confirm our theoretical model while improving performance with faster droplet speeds of up to 4.5 cm/s, a more than 2× improvement. Basic droplet manipulations such as the merging of multiple droplets, the ability to accommodate and move droplets of differing volumes, and individual droplets operating in parallel freely around the two-dimensional device plane are still feasible

Summary

Introduction

Droplet-based digital microfluidics addresses many requirements for lab-on-a-chip systems through the ability to process a large number of samples using reduced sample and reagent volumes while increasing detection sensitivity. The first is individual waterin-oil emulsions that flow through microfluidic channels such as in the continuous flow microfluidic paradigm.[14,15,16,17,18,19] This type of droplet microfluidics benefits from its high throughput ability to rapidly produce water-in-oil emulsions. These droplets must be processed sequentially as customizable operations for unique droplets are not feasible. Droplets are often actuated by electrical, optical, or magnetic means

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