Biological cells are major building blocks of tissues and organs of living organisms. These cells are also being used as biomarkers for diagnosis and sources for regenerative medicine. To better understand and even regulate diverse activities of cells, materials capable of interacting with cells have been designed by integrating various material chemistry, characterization, and processing techniques. These materials are often integrated with various nano- and microscale engineering devices. In this article, we provide an overview of materials for biological modulation, sensing, and imaging and also discuss opportunities for the future development of multifunctional materials for sensing and therapies.