The research areas we are involved in span soft condensed matter physics, applied physics and photonics, physical chemistry of charged interfaces, and single molecule science. At the level of experimental techniques, we rely on a combination of advanced nanofabrication, optical imaging and detection. Projects in my group tend to be fairly interdiscplinary. Following are a few areas we currently work on:

We have demonstrated for the first time the ability to obtain digital functionalities such as switching, gating and data storage in a single levitating colloidal particle in solution. This single colloid switch is capable of operation using femtojoule energies and at switching times approaching 100 ns.

We are able to stably trap single biomolecules such as DNA and proteins with a tunable timescale of milliseconds to hours. Depicted above is an Intrinsically Disordered Protein (IDP) passively trapped for more than 30 minutes.

We have achieved for the first time the ability to perform sub-elementary-charge resolved measurements of the effective electrical charge of a single macromolecule in real time. Our long term goal is to investigate the use of electrical charge to read out structural fluctuations and conformational changes in single biomolecules in solution.

We observe intermediate-range attractive interactions between confined like-charged entities where Poisson-Boltzmann mean field theory only predicts monotonic repulsion. Uncovering the origin of this attraction remains a question of central interest in our lab.

We perform numerical calculations of interaction free energies for confined charged objects (molecules and particles) based on the non-linear Poisson-Boltzmann equation. We also perform extensive Brownian Dynamics simulations to capture the dynamics of and intepret our single-molecule and single-particle experiments.