Digitally controllable large-scale integrated microfluidic systems.

Lam Raymond Hiu-wai.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references (leaves 87-91).Abstracts in English and Chinese.Abstract --- p.iiAbstract (Chinese) --- p.ivAcknowledgment --- p.vContents --- p.viiList of Figures --- p.ixIntroduction --- p.1Chapter 1-1 --- Overview of MEMS and Microfluidic Technologies --- p.1Chapter 1-1-1 --- Microelectromechanical Systems (MEMS) --- p.1Chapter 1-1-2 --- Microfluidic Systems --- p.2Chapter 1-2 --- Literture Review on Microfluidic Devices --- p.4Chapter 1-2-1 --- Micropumps --- p.4Chapter 1-2-2 --- Microvalves --- p.5Chapter 1-2-3 --- Micromixers --- p.5Chapter 1-2-3 --- Integration of Multiple Devices: Microfluidic Systems --- p.6Chapter 1-3 --- Motivation and Research Objectives --- p.7Chapter 1-4 --- Thesis Outline --- p.9Fluid Flow in MicroChannel --- p.11Chapter 2-1 --- Velocity Profile in a MicroChannel --- p.11Chapter 2-2 --- Pressure Dissipation by Laminar Friction --- p.16Chapter 2-3 --- Bubble Filtering --- p.20Microfluidic Centrifugal Pumping --- p.23Chapter 3-1 --- Vortex Micropump --- p.23Chapter 3-1-1 --- Operation Principle and Device Design --- p.23Chapter 3-1-2 --- Alternative Pump Design --- p.25Chapter 3-2 --- Micropump Fabrication --- p.27Chapter 3-2-1 --- Electroplated Impeller --- p.27Chapter 3-2-2 --- SU-8 Impeller --- p.30Chapter 3-2-3 --- Micropump Fabricated by Micro Molding Replication Technique --- p.32Chapter 3-2-4 --- Inverted-chamber Vortex Micropump --- p.35Chapter 3-3 --- Elementary Centrifugal Pump Theory --- p.36Chapter 3-3-1 --- Pumping Pressure and Discharge --- p.36Chapter 3-3-2 --- Fluid Horsepower --- p.38Chapter 3-3-3 --- Effect of Blade Angle --- p.40Chapter 3-4 --- Pumping Specification --- p.41Mixing Based on Mechanical Vibration --- p.47Chapter 4-1 --- Micromixer Design --- p.47Chapter 4-1-1 --- Oscillating Diaphragm Actuated Microfluidic Mixing --- p.47Chapter 4-1-2 --- Flat-surface Diaphragm Active Micromixer --- p.48Chapter 4-1-3 --- Mixing Enhancement by Pillared Chamber Profile --- p.50Chapter 4-2 --- Fabrication Process --- p.52Chapter 4-2-1 --- Flat-surface Diaphragm Active Micromixer --- p.52Chapter 4-2-2 --- Pillared-surface Diaphragm Active Micromixer --- p.54Chapter 4-3 --- Experimental Analysis of Mixing Performance --- p.56Microfluidic Flow Planning System --- p.63Chapter 5-1 --- System Design --- p.63Chapter 5-1-1 --- Chip Design and Fabrication --- p.63Chapter 5-1-2 --- Digital Controlling System --- p.65Chapter 5-1-3 --- Operation Mechanism --- p.67Chapter 5-2 --- Experimental Results --- p.69Microfluidic Mixing Module Array --- p.70Chapter 6-1 --- System Configuration --- p.70Chapter 6-1-1 --- Microfluidic Chip Design --- p.70Chapter 6-1-2 --- Backward Flow Elimination by Tesla Valve --- p.72Chapter 6-1-3 --- System Controller and Operation Mechanism --- p.75Chapter 6-2 --- Fabrication --- p.76Chapter 6-3 --- Mixing Ratio Estimation --- p.78Chapter 6-4 --- Experimental Results --- p.79Conclusion --- p.81Future Work --- p.83Chapter 8-1 --- Self Driven Microfluidic Flow Planning System --- p.83Chapter 8-2 --- Mixing Enhancement by Cavitation Microstreaming --- p.84References --- p.87Bonding Test on UV-curing Epoxy Resin --- p.92Circuit Schematic of Digital Controller --- p.94Advanced Digital Microfluidic Controller --- p.9

Microfluidics for protein biophysics

Microfluidics has the potential to transform experimental approaches across the life sciences. In this review, we discuss recent advances enabled by the development and application of microfluidic approaches to protein biophysics. We focus on areas where key fundamental features of microfluidics open up new possibilities and present advantages beyond low volumes and short time-scale analysis, conventionally provided by microfluidics. We discuss the two most commonly used forms of microfluidic technology, single-phase laminar flow and multiphase microfluidics. We explore how the understanding and control of the characteristic physical features of the microfluidic regime, the integration of microfluidics with orthogonal systems and the generation of well-defined microenvironments can be used to develop novel devices and methods in protein biophysics for sample manipulation, functional and structural studies, detection and material processing

Immunochromatographic diagnostic test analysis using Google Glass.

We demonstrate a Google Glass-based rapid diagnostic test (RDT) reader platform capable of qualitative and quantitative measurements of various lateral flow immunochromatographic assays and similar biomedical diagnostics tests. Using a custom-written Glass application and without any external hardware attachments, one or more RDTs labeled with Quick Response (QR) code identifiers are simultaneously imaged using the built-in camera of the Google Glass that is based on a hands-free and voice-controlled interface and digitally transmitted to a server for digital processing. The acquired JPEG images are automatically processed to locate all the RDTs and, for each RDT, to produce a quantitative diagnostic result, which is returned to the Google Glass (i.e., the user) and also stored on a central server along with the RDT image, QR code, and other related information (e.g., demographic data). The same server also provides a dynamic spatiotemporal map and real-time statistics for uploaded RDT results accessible through Internet browsers. We tested this Google Glass-based diagnostic platform using qualitative (i.e., yes/no) human immunodeficiency virus (HIV) and quantitative prostate-specific antigen (PSA) tests. For the quantitative RDTs, we measured activated tests at various concentrations ranging from 0 to 200 ng/mL for free and total PSA. This wearable RDT reader platform running on Google Glass combines a hands-free sensing and image capture interface with powerful servers running our custom image processing codes, and it can be quite useful for real-time spatiotemporal tracking of various diseases and personal medical conditions, providing a valuable tool for epidemiology and mobile health

Bioengineered Textiles and Nonwovens – the convergence of bio-miniaturisation and electroactive conductive polymers for assistive healthcare, portable power and design-led wearable technology

Today, there is an opportunity to bring together creative design activities to exploit the responsive and adaptive ‘smart’ materials that are a result of rapid development in electro, photo active polymers or OFEDs (organic thin film electronic devices), bio-responsive hydrogels, integrated into MEMS/NEMS devices and systems respectively. Some of these integrated systems are summarised in this paper, highlighting their use to create enhanced functionality in textiles, fabrics and non-woven large area thin films. By understanding the characteristics and properties of OFEDs and bio polymers and how they can be transformed into implementable physical forms, innovative products and services can be developed, with wide implications. The paper outlines some of these opportunities and applications, in particular, an ambient living platform, dealing with human centred needs, of people at work, people at home and people at play. The innovative design affords the accelerated development of intelligent materials (interactive, responsive and adaptive) for a new product & service design landscape, encompassing assistive healthcare (smart bandages and digital theranostics), ambient living, renewable energy (organic PV and solar textiles), interactive consumer products, interactive personal & beauty care (e-Scent) and a more intelligent built environment

Integrated Control of Microfluidics – Application in Fluid Routing, Sensor Synchronization, and Real-Time Feedback Control

Microfluidic applications range from combinatorial chemical synthesis to high-throughput screening, with platforms integrating analog perfusion components, digitally controlled microvalves, and a range of sensors that demand a variety of communication protocols. A comprehensive solution for microfluidic control has to support an arbitrary combination of microfluidic components and to meet the demand for easy-to-operate system as it arises from the growing community of unspecialized microfluidics users. It should also be an easy to modify and extendable platform, which offer an adequate computational resources, preferably without a need for a local computer terminal for increased mobility. Here we will describe several implementation of microfluidics control technologies and propose a microprocessor-based unit that unifies them. Integrated control can streamline the generation process of complex perfusion sequences required for sensor-integrated microfluidic platforms that demand iterative operation procedures such as calibration, sensing, data acquisition, and decision making. It also enables the implementation of intricate optimization protocols, which often require significant computational resources. System integration is an imperative developmental milestone for the field of microfluidics, both in terms of the scalability of increasingly complex platforms that still lack standardization, and the incorporation and adoption of emerging technologies in biomedical research. Here we describe a modular integration and synchronization of a complex multicomponent microfluidic platform

Establishment of a Perfusion Process with Antibody-Producing CHO Cells Using a 3D-Printed Microfluidic Spiral Separator with Web-Based Flow Control

Monoclonal antibodies are increasingly dominating the market for human therapeutic and diagnostic agents. For this reason, continuous methods—such as perfusion processes—are being explored and optimized in an ongoing effort to increase product yields. Unfortunately, many established cell retention devices—such as tangential flow filtration—rely on membranes that are prone to clogging, fouling, and undesirable product retention at high cell densities. To circumvent these problems, in this work, we have developed a 3D-printed microfluidic spiral separator for cell retention, which can readily be adapted and replaced according to process conditions (i.e., a plug-and-play system) due to the fast and flexible 3D printing technique. In addition, this system was also expanded to include automatic flushing, web-based control, and notification via a cellphone application. This set-up constitutes a proof of concept that was successful at inducing a stable process operation at a viable cell concentration of 10–17 × 106 cells/mL in a hybrid mode (with alternating cell retention and cell bleed phases) while significantly reducing both shear stress and channel blockage. In addition to increasing efficiency to nearly 100%, this microfluidic device also improved production conditions by successfully separating dead cells and cell debris and increasing cell viability within the bioreactor

Droplets Formation and Merging in Two-Phase Flow Microfluidics

Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i) the emulsification step should lead to a very well controlled drop size (distribution); and (ii) the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed

Porous Biomimetic Microlens Arrays as Multifunctional Optical Structures

Microlenses are important optical components that image, detect and couple light. Most synthetic microlenses, however, have fixed position and shape once they are fabricated. Therefore, the attainable range of their tunability and complexity is rather limited. In comparison, biological world provides a multitude of varied, new paradigms for the development of adaptive optical networks. This review discusses a few inspirational examples of biological lenses and their synthetic analogs. We focus on the fabrication and characterization of biomimetic microlens arrays with integrated pores, whose appearance and function are similar to a highly efficient optical element formed by brittlestars. The complex microlens design can be created by three-beam interference lithography. These synthetic microlenses have strong focusing ability, and the structure can be, therefore, used as an adjustable lithographic mask, and a tunable optical device coupled with the microfluidic system. The replacement of rigid microlenses with soft hydrogels provides means for changing the lens geometry and refractive index continuously in response to external stimuli, resulting in intelligent, multifunctional, tunable optics

Industrial lab-on-a-chip: design, applications and scale-up for drug discovery and delivery

Microfluidics is an emerging and promising interdisciplinary technology which offers powerful platforms for precise production of novel functional materials (e.g., emulsion droplets, microcapsules, and nanoparticles as drug delivery vehicles- and drug molecules) as well as high-throughput analyses (e.g., bioassays, detection, and diagnostics). In particular, multiphase microfluidics is a rapidly growing technology and has beneficial applications in various fields including biomedicals, chemicals, and foods. In this review, we first describe the fundamentals and latest developments in multiphase microfluidics for producing biocompatible materials that are precisely controlled in size, shape, internal morphology and composition. We next describe some microfluidic applications that synthesize drug molecules, handle biological substances and biological units, and imitate biological organs. We also highlight and discuss design, applications and scale up of droplet- and flow-based microfluidic devices used for drug discovery and delivery. © 2013 Elsevier B.V. All rights reserved

From microfluidics to hierarchical hydrogel materials

Over the past two decades, microfluidics has made significant contributions to material and life sciences, particularly via the design of nano-, micro- and mesoscale materials such as nanoparticles, micelles, vesicles, emulsion droplets, and microgels. Unmatched in control over a multitude of material parameters, microfluidics has also shed light on fundamental aspects of material design such as the early stages of nucleation and growth processes as well as structure evolution. Exemplarily, polymer hydrogel particles can be formed via microfluidics with exact control over size, shape, functionalization, compartmentalization, and mechanics that is hardly found in any other processing method. Interestingly, the utilization of microfluidics for material design largely focuses on the fabrication of single entities that act as reaction volume for organic and cell-free biosynthesis, cell mimics, or local environment for cell culturing. In recent years, however, hydrogel design has shifted towards structures that integrate a large variety of functions, e.g., to address the demands for sensing tasks in a complex environment or more closely mimicking architecture and organization of tissue by multiparametric cultures. Hence, this review provides an overview of recent literature that explores microfluidics for fabricating hydrogel materials that go well beyond common length scales as well as the structural and functional complexity of microgels necessary to produce hierarchical hydrogel structures. We focus on examples that utilize microfluidics to design microgel-based assemblies, on microfluidically made polymer microgels for 3D bioprinting, on hydrogels fabricated by microfluidics in a continuous fashion, like fibers, and on hydrogel structures that are shaped by microchannels