Recent developments in DNA sequencing technologies have resulted in substantial reductions in time and cost for large scale sequencing efforts. However, the routine sequencing of individual human genomes for personalized medicine and point-of-care clinical applications will require future-generation DNA sequencing technologies to achieve unprecedented multiplexing, sample throughput and cost reductions. There is also a need for tools and techniques for interrogating proteins in a sensitive, quantitative, multiplexed and high-throughput manner. To enable further miniaturization and parallelization for such analyses, I have developed new methods and technologies for fabricating and assembling high-density DNA and protein arrays. Microfabrication techniques were utilized to construct various platforms upon which DNA and protein conjugated microbeads can be assembled. Electric and magnetic fields are employed to accelerate the assembly process and achieve unprecedented filling efficiencies. I have also demonstrated the utility of such arrays as a platform for multiplexed protein detection. In addition, I have developed a method for fabricating DNA polymer brush arrays in microfluidic devices. These arrays may be useful for enhancing the sensitivity of microarrays and the yield, efficiency and order of solid-phase DNA amplification.