Professor Madhavi Krishnan

Tutor in Physical Chemistry, Associate Professor in Physical Chemistry
Research

Areas of interest: Single molecule science, intermolecular interactions, electrostatics at the nanoscale, biophysics and soft condensed matter

A microscopic bit of matter in solution is in continuous motion. Pummelled at random by the solvent, it engages in a Brownian walk that will eventually take it far away from where we first started to observe it. At the nanometre scale, even gravity is too weak to influence the trajectory of the object. Placing surfaces in the vicinity however puts new forces into play. By appropriately tailoring the geometry of the walls we are able to harness these intrinsic object-wall forces and manoeuvre our entity of interest into a desired spatial location and orientation in a fluid. Once there, the object levitates stably for long periods, permitting us to measure its properties and interactions very precisely, and in some experiments even use the levitating object to perform technologically relevant functions.

Beyond spatial control of molecules, we have a strong interest in measurement - of molecular physical properties, dynamics and interactions. Molecular electrostatics has remained relatively unexplored terrain at the experimental level, and a new line of activity unfolding in my lab focuses on understanding vital aspects of intermolecular interactions that have eluded scrutiny thus far. Besides potentially making their way into practical devices such as ultrasensitive and highly precise molecular sensors, possibly even memories and displays, our findings are continually pushing the envelope on control, manipulation of and fundamental measurements on matter at the nanometre scale.

Teaching

Thermodynamics, Statistical Mechanics, Soft condensed matter and biophysics.

Publications

'Single-molecule electrometry', Ruggeri et al. & Krishnan, Nature Nanotechnology 12 (2017) 488-495

'Information storage and retrieval in a single levitating colloidal particle', Myers, Celebrano & Krishnan, Nature Nanotechnology 10 (2015) 886-891

'Measuring the size and charge of single nanoscale objects in solution using an electrostatic fluidic trap', Mojarad & Krishnan, Nature Nanotechnology 7 (2012) 448-452

'Geometry-induced electrostatic trapping of nanometric objects in a fluid', Krishnan et al., Nature 467 (2010) 692-695