Mechanical and Civil Engineering Seminar
Mechanical and Civil Engineering Seminar Series
Title: Concentration enrichment, separation, and ion exchange in nanoliter-scale water-in-oil droplets
Abstract: Droplet-based techniques have had a profound impact in chemistry, owing to an ability to perform rapid and massively parallel reactions in minute fluid volumes. In many applications, concentration enrichment is required to increase the speed of reactions or the sensitivity of assays; but in-droplet concentration enrichment remains challenging. This talk will focus on recent developments in the Anand laboratory aimed at controlling droplet composition. We recently interfaced electrokinetic concentration polarization with droplet microfluidics to accomplish in-droplet de-mixing. This result is significant because the concentration of any charged species in the droplet can be enriched, and the approach can be readily integrated into existing droplet workflows. The talk will further describe results that show electrokinetic separation of two anionic fluorophores within droplets. Such a capability potentiates the droplet-templated synthesis of particles with gradient composition and the development of mobility-shift assays, which rely on discrimination of multiple species tagged with a single-color fluorophore. Finally, by using a calcium-binding dye as an indicator, we demonstrate in-droplet cation exchange. This demonstration of cation exchange in droplets is significant because of its broad applicability to strategies for synthesis and bioassays. These results lay the foundation for new advanced droplet techniques with transformative applications.
Bio: Robbyn K. Anand is the Suresh Faculty Fellow and Carlyle G. Caldwell Endowed Chair in Chemistry at Iowa State University where she joined the Department of Chemistry as an Assistant Professor in August 2015. She earned her Ph.D. in 2010 from the University of Texas at Austin under the guidance of Prof. Richard M. Crooks with the support of an NSF Graduate Research Fellowship. She developed microfluidic devices employing bipolar electrodes for electrokinetic focusing of charged species. Then, as an NIH Postdoctoral Fellow, she worked with Prof. Daniel T. Chiu at the University of Washington on the capture and analysis of circulating tumor cells. At Iowa State, her group has developed methods for circulating tumor cell analysis, electrokinetic enrichment, and separation of chemical species within water-in-oil droplets, and more sensitive bioanalysis at arrays of wireless bipolar electrodes. These achievements have led to her recognition in 2021 with the Pittsburgh Conference Achievement Award, the Satinder Ahuja Award for Young Investigators in Separations Science, the Royce W. Murray Young Investigator Award, and the Analytical Chemistry Young Innovator Award. During this time, Prof. Anand also founded the Midwest Retreat for Diversity in Chemistry - an annual event aimed at the retention of underrepresented groups in the chemical enterprise.
NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors with a valid Caltech ID.