He holds joint appointments in Molecular and Cellular Biology as well as in the College of Optical Sciences, and is a member of the Applied Mathematics Graduate Interdisciplinary Program. His research focuses on the role of mechanical force in Biology using single-molecule techniques such as optical tweezers. He pioneered the so called molecular force clamp, a feedback controlled optical tweezers that is able to maintain a constant force on a single individual moving motor protein. Recent interests are RNA structure, nucleic acid-protein interactions interactions, and translational recoding via -1 frameshifting.