ESPCI web site
Madhavi Krishnan
Title : Control, manipulation and measurement of matter at the nanometer scale : from single molecule science to mesoscopic digital devices
Abstract : The desire to “freely suspend the constituents of matter” in order to study their behaviour can be traced back over 200 years to the diaries of Lichtenberg. From radio-frequency ion traps to optical tweezing of colloidal particles, existing methods to trap matter in free space or
solution rely on the use of external fields that often strongly perturb the integrity of a macromolecule in solution. Recently, I introduced the ‘electrostatic fluidic trap’, a “field-free” principle that supports stable, non-destructive confinement of single macromolecules in room temperature fluids, representing a paradigm shift in a nearly century-old field. The spatio-temporal dynamics of a single electrostatically trapped molecule reveals fundamental information on its properties, e.g., size and electrical charge. We have recently developed the ability to measure the electrical charge of a single macromolecule in solution with a precision much better than a single elementary charge. Since the electrical charge of a macromolecule in solution is in turn a strong function of its 3D conformation, our approach enables for the first time precise, general measurements of the relationship between 3D structure and electrical charge of a single macromolecule, in real time. I will also discuss a second sphere of activity where we use external electrical and optical forces in conjunction with our trap in order to achieve digital functionalities such as data storage and signal gating in a single levitating colloidal particle.