Development of Plug-and-Play 3D-Printed Micropneumatic Circuit Modules for Autonomous Control of Fluidic Devices

Abstract

This dissertation presents an exploration of the design, fabrication, and characterization of integrated pneumatic circuits for the precise control of microvalves within droplet-based microfluidic devices. By integrating these pneumatic logic elements, this research demonstrates automatic, on-chip control over aqueous-in-oil droplet generation in microfluidic devices. These findings advance the field of autonomous lab-on-a-chip systems by reducing reliance on electronic devices and programming languages, promoting the development of more compact, portable, and complex microfluidic devices for diverse applications. Chapter 1 introduces microfluidics as an analytical method which uses minute amounts of fluid, as well as fundamentals of microfluidics and droplet-based microfluidics. Valving on these devices is briefly discussed, followed by traditional and modern fabrication methods, including 3D printing. Chapter 2 focuses on the design and fabrication of basic pneumatic logic gates and their characteristics. It also introduces our plug-and-play pneumatic logic gates and our contributions to split-path logic gates. This chapter concludes by discussing our pneumatic multiplexer and diode design and their capabilities. Chapter 3 initiates the development of using a smartphone’s microphone as an instrument to collect high frequency data, mainly the sound from an exhaust of a pneumatic inverter gate while an oscillator is running. This chapter also describes how we analyzed the data collected with smartphones using Audacity, MATLAB, ImageJ, and Excel. Chapter 4 unveils how we constructed a pneumatic computer with only NOT and NAND gates, consisting of an oscillator, delay buffer, XOR gate, and AND gate. Droplets were created with a 3D-printed droplet generator using the pneumatic computer to control a valve on the device. Also, plug-and-play pneumatic buffers were used to permit manual control of droplet volumes with two nanoliter precision, without any electronic controllers. Chapter 5 covers micropumps and micromixers and how we leverage pneumatic oscillators to control 3D-printed mixers towards a bioanalytical chemistry application. These devices were customized for our electrochemical bowtie sensors and designed to reduce the mixing time of analyte and antibody in the assay workflow. Chapter 6 concludes this dissertation, including future directions for projects mentioned.