Because of its microscopic size and predictable modular structure, DNA is an ideal building material for nanoscale devices. These DNA-based nanodevices can function as platforms that allow testing of certain features of molecular circuits in carefully controlled settings. Yamuna Krishnan explains how her team creates these nanodevices to target cancer cells in living beings, interpret biochemical signals to report on health and find disease, and more. Yamuna Krishnan is a professor and Brain Research Foundation Fellow of Chemistry and the Grossman Institute of Neuroscience, Quantitative Biology, and Human Behavior at the University of Chicago. She received a PhD from the Indian Institute of Science, Bangalore, and pursued postdoctoral studies as an 1851 Research Fellow at the University of Cambridge. Her honors include the Shanti Swarup Bhatnagar Award in Chemical Sciences, a Wellcome Trust/DBT India Alliance Senior Research Fellowship, the AVRA Young Scientist Award, Associateship of the Indian Academy of Sciences, the Innovative Young Biotechnologist Award, and, most recently, selection as one of Cell’s 40 under 40 list of scientists worldwide who are shaping trends in biology.