Microfluidics and Their Role in Biomedical ApplicationsExecutive SummaryTable of ContentsIntroductionBiomedical ApplicationsOverviewLab-on-a-ChipDrug Delivery and Micro-Dosing SystemsMicrofluidic Device Focus: ValvesMaterialsProcess OverviewFabrication of a ValveFuture of MicrofluidicsReferencesMicrofluidics andTheir Role inBiomedicalApplicationsMay 14th, 2003ENMA 465By Susan Beatty, Stacy Cabrera, Saba Choudhary, andDaniel Janiak0http://www.mae.ufl.edu/~zhf/ResearchInterests-ZHFan.htmExecutive SummaryMicrofluidics focus on controlling the flow of liquids and gases in systems with dimensions on the microscale. These fluids are dealt with in nano and picoliter amounts and are subject to specific properties at this level. Microfluidic devices are very promising to biomedical applications and play a key role in the future of laboratory testing. Applications in this area can range from detecting toxins in the air to identifying DNA sequences. The idea behind “lab-on-a-chip” processes is that a macroscale laboratory and all of its functions can be downsized to fit on a microchip. Micro-dosing systems are also being developed for drug delivery with microfluidic systems that involve channels, pumps, valves, and sensors. In the beginning of the research, the material of choice was silicon. Because silicon is not completely bioinert and fairly expensive to process, manufacturers have since moved to plastics. Some of the common materials reviewed include Polyimide, Parylene, PDMS, and Diamond-Like Carbon films. The primary process for making the channels of the device is soft lithography, while micromachining is used to create other features like valves. A key component to a microfluidics system is a valve. The materials and processes of choice depend on the valve being manufactured and the function of the valve within the system. One of the main key concepts currently being improved on is mixing 1techniques among fluids with only laminar flow properties The future of microfluidics is to continue to take the processing to a smaller and smaller level with increasing speed, accuracy and range of tests being conducted on a microchip.Key Words: Microfluidics, biomedical, valve device., soft lithographyTable of ContentsExecutive Summary 1Introduction 3Biomedical ApplicationsOverview 4Lab-on-a-chip 6Drug Delivery and Micro-Dosing Systems 6Microfluidic Device Focus: Valves 7Materials 8ProcessesOverview 11Fabrication of a Valve 13Future of Microfluidics 152References 163The idea is that once you master fluids at the microscale, you can automate key experiments for genomics and pharmaceutical development, perform instant diagnostic tests, even build implantable drug-delivery devices—all on mass produced chips. It’s a vision so compelling that many industry observers predict microfluids will do for biotech what the transistor did for electronics. - Rebecca Zacks for Technology Review Jan/Feb 2001IntroductionIn the most general sense, microfluidics is the flow control of tiny amounts of gases or liquids in a miniaturized system on a microchip (Fluidigm, 2003). This is a growing area of biotechnology that will attempt to bring an entire lab, all its equipment, and its range of tests to a single piece built on a microscale. Examples of microfluidics can be found in nature—one prominent one being the human body’s oxygen transport system. Fluid (plasma carrying tiny red blood cells) is moved through tiny capillaries bringing the material to all extremities of the body (Holl et al., 2002). In comparison, microfluidic systems in biotechnology are made up of a combination of channels, pumps, valves, and sensors and are referred to as Micro Total Analysis Systems (mTAS). These channels and chambers within the systems are at the dimensions of tens of hundreds of micrometers (Holl, et al., 2002). The motivation behind developing microfluidics is the properties of laminar flow that exist within the system. On a macroscale, laminar, turbulent and random flow exists for fluids whereas there is only laminar flow on a microscale. Because only this particular type of flow exists in confined spaces, micro channels create special environments that provide controlled mixing—a critical step in expediting chemical reactions (Holl et al., 2002). The area of microfluidics is also looked to for its low thermal mass and efficient mass transport (Holl, et al., 2002). Finally, these miniature systems are the first step to automating complex experimental processes (Fluidigm, 2003).The processing of microfluidic systems is just as important as the inventions of them. Microfabrication methods from the electronics industry have been adapted to microfluidic system processing. Methods range from “printing” to soft lithography and everything in between.Different materials types, such as ceramics and plastics are also used to make the various parts including the pumps, valves, and channels. 4The future of microfluidics can bring professional, large scale, cumbersome, yet important tests to an individual, at-home level by building personal microfluidic devices, similar to the way microcomputing brought a computer into nearly every person’s home. The focus lies on uses in biotechnology but the possibilities for electronics and more exists. Biomedical ApplicationsOverviewMicrofluidics studies the behavior of liquids and gasses at the micro level and exploits these properties, or finds methods of circumventing them, in applications and designs for device fabrication. Microfluidic devices combine the advantages of the chemical and physical properties of liquids and gasses at the micro level with the electrical properties of semiconductors on a single chip. This breakthrough in technology finds great potential in the biomedical field. Applications range from detecting airborne toxins to analyzing DNA sequences. Advantages in using these small-scale devices rather than conventional systems include: compact size, disposability, increased functionality, and they require smaller volumes ofreagents and samples. According to Harold Craighead of Cornell University, himself a researcher in the area, commercialization of the technology is seen for more rapid DNA sequencing, chemical analytical systems, manipulating cells, and doing general biological procedures (Gwynne, 2000).The optimism surrounding the future of microfluidics is reinforced by the fact that fabrication of the devices involves techniques compatible