Integration of World-to-Chip Interfaces with Digital Microfluidics for Bacterial Transformation and Enzymatic Assays

Digital microfluidics (DMF) represents an alternative to the conventional microfluidic paradigm of transporting fluids in enclosed channels. One of the major benefits of DMF is that fluid motion and control is achieved without external pumps. The automation component of DMF have pushed the barriers of this "lab-on-chip" technology. However, integration with external components (i.e., "world-to-chip") interfaces have been a challenge. Two common "world-to-chip" challenges are (1) delivering biological samples to DMF devices and (2) accurately controlling temperatures on device. To address these challenges, this work describes two "world-to-chip" interface features that have been integrated on a DMF platform: a reagent delivery system and a thermal control apparatus. This platform enables a variety of biological or chemical experiments to be conducted on-chip while reducing manual intervention. Specifically, our platform increases reagent volumes available to device reservoirs volume by at least 50-fold eliminating the need to manually refill reservoirs while improving droplet dispensing reproducibility. In addition, we have integrated a closed-loop temperature control system that offers precise temperature control on-chip. To validate our "world-to-chip" interface, we have automated bacterial transformation and enzymatic assay protocols, showing that such a system enhances DMF performance. Overall, we propose that this system will improve biological experimentation which requires fluidic and temperature control integrated on DMF platforms.