Aptamer-based assays are a powerful platform for sensing a wide variety of biochemical targets, including drugs, disease biomarker, and biomolecules. However, aptamer assays often lack rapid identification and high-throughput screening. Performing an aptamer-based assay on a microfluidic device is a promising solution to increase throughput, portability, and sensitivity. In this paper, we present a microfluidic device capable of running aptamer-based assays. Our device utilizes normally-closed valves and a central micropump to move fluids throughout the chip. One chip could theoretically be scaled up to run multiple assays, and multiple of these microfluidic devices could be run in parallel to increase throughput. Our experiments characterized the actuation pressure needed to normally-closed valves with different size parameters, showed and characterized flow using both oil and water solutions, and demonstrated modular movement on a chip with six micropumps. Lastly, we designed a cartridge topper system to eliminate the need for pins leading to a pneumatic controller so chips could easily be switched out. By demonstrating flow and mixing, our chip is fully capable of running an aptamer-based assay