Development of an automated and scalable lab-on-a-chip platform with on-chip characterization

Digital Microfluidics (DMF) is a fluid-handling technique that enables precise control of drops on an array of electrodes using electrostatic forces. In contrast to most other lab-on-a-chip technologies (e.g., channel-based microfluidics), DMF is highly reconfigurable (i.e., function is defined by software and not by the physical structure of the chips). Thus, DMF offers the possibility for a truly general-purpose lab-on-a-chip platform, where a wide variety of biological and chemical protocols may be implemented at the microscale, under automated control, and on a generic chip. Widespread adoption of this technology has thus far been limited by: (1) lack of access to control hardware/software, (2) the high-cost and specialized equipment required for fabricating DMF chips, (3) an incomplete understanding of DMF device physics, and (4) lack of methods for performing on-chip characterization. This thesis aims to address these limitations. We describe the development of a control instrument and software capable of applying a precise electrostatic force and measuring device capacitance, drop position, and drop velocity on-chip. We also demonstrate a low-cost method for fabricating DMF devices that does not require a cleanroom facility: inkjet printing of silver electrodes on paper. We present new on-chip methods for characterizing the resistive forces that oppose drop movement on DMF and report the results from an initial screen of conditions, establishing the effects of surface tension, conductivity, viscosity, protein content, and driving frequency on resistive forces. Finally, we demonstrate an extension of impedance-based drop sensing techniques (e.g., device capacitance, drop position, and drop velocity) to facilitate measurement across multiple electrodes in parallel. In combination, these advancements represent significant progress toward the goal of establishing a general-purpose lab-on-a-chip platform that is accessible to the wider biomedical and chemical research communities.Ph.D.2017-07-06 00:00:0