| This thesis describes the design, fabrication, and operation of fluidic devices that are made in a transparent, elastomeric polymer, poly(dimethylsiloxane) (PDMS). The first chapter of this thesis introduces the area of microfluidics, and focuses on the advantages of making microfluidic systems in PDMS, rather than in conventional materials such as glass and silicon. The chapter describes several components that give rise to different functionalities in microfluidic devices, and provides an overview of the integration of these components towards complete analytical systems.; Chapter 2 describes in detail one of the components reviewed in Chapter 1, a polymeric membrane that---when integrated into microfluidic devices---can be used to control convective transport of fluid between crossing channels. The design of this system enabled chemical and biochemical reactions to take place at each of the crossings. Several reactions can, therefore, take place in parallel by using an array format.; Chapter 3 extends the work from the previous chapter and demonstrates how these fluidic arrays can be combined with a serial dilution network to carry out immunoassays using a miniaturized format. The format of this assay is similar to an ELISA-type assay, except that the on-chip serial dilution of analytes replaces the manual dilution used in conventional immunoassays. This microfluidic immunoassay analyzes multiple analytes simultaneously, using only a few microliters of sample.; Chapter 4 shifts away from devices comprised of microfluidic channels, and describes an unconventional fluidic device. Here, a fluid/air interface is the medium in which gears self-assemble into a simple machine. These gears are driven externally and indirectly by magnetic interactions; they exert forces on each other through a balance of mechanical interaction, hydrodynamic shear, magnetic forces, and capillarity.; Many fluidic devices, including ones described in Chapters 1--3, employ aqueous solutions and involve the manipulation of biochemical species. The purpose of Chapter 5 is to describe the compatibility of organic solvents with PDMS, and to assess the ability to perform organic reactions in fluidic devices that are made in this polymer. Chapter 6 extends the study of the compatibility of PDMS to mammalian cells, as PDMS has properties that are attractive for applications in cell biology. This chapter evaluates the influence of the composition of PDMS on the ability to culture different types of mammalian cells that are commonly used in cell culture. |
