The National Institute of Standards and Technology (NIST) is the National Metrology Institute for the USA. Our mission is to advance measurement science, standards and technology in ways that enhance economic security and improve quality of life in the USA. Due to the increased need for technologies that advance biological research and the many new and exciting innovations in microfluidics, our projects are aimed at engineering well-controlled microenvironments for quantitative measurements of cell behavior in microfluidic systems. Cell-based microfluidics at NIST is a highly multidisciplinary activity and is greatly influenced by NIST programs in biochemical sciences, materials science, engineering and information technology. Although there are many microfluidic-related activities ongoing at NIST, we will focus on projects related to cell-based measurements in this article.