Sunday, May 13, 2018
4:00 p.m. – 5:00 p.m.
Auditorium between bldg. 4&5, Level 0, Room 0215
Molecular Transport through Atomically Smooth Angstrom-Scale capillaries
Abstract:
It has been an ultimate but seemingly distant goal of nanofluidics to controllably fabricate capillaries with dimensions approaching the size of small ions and water molecules. Nanometre-scale pores and capillaries have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to fabricate artificial capillaries with nanometre dimensions, which has enabled new research on molecular transport and led to the emergence of nanofluidics. But surface roughness in particular makes it challenging to produce capillaries with precisely controlled dimensions at this spatial scale. We have developed a method for fabrication of narrow and smooth capillaries through van der Waals assembly, with atomically flat sheets at the top and bottom separated by spacers made of two-dimensional crystals with a precisely controlled number of layers. Water transport through the channels, ranging in height from one to several dozen atomic planes, is characterized by unexpectedly fast flow (up to 1 metre per second) that we attribute to high capillary pressures (about 1,000 bar) and large slip lengths. For channels that accommodate only a few layers of water, the flow exhibits a marked enhancement that we associate with an increased structural order in nanoconfined water. In this talk, I will also discuss about the fundamentals of ion transport through these capillaries. Our work opens up an avenue to making capillaries and cavities with sizes tunable to ångström precision, and with permeation properties further controlled through a wide choice of atomically flat materials available for channel walls. Our results lay the basis for exploration of such Å-size slits in nanofluidics, molecular separation and other nanotechnologies.
References: [1] B. Radha et al., Molecular transport through capillaries made with atomic-scale precision. Nature 538, 222-225 (2016). [2] A. Esfandiar et al., Size effect in ion transport through angstrom-scale slits. Science 358, 511-513 (2017).
Bio:
Radha Boya is currently a Kathleen Ollerenshaw fellow in condensed matter physics group, at the University of Manchester where she is exploring the fundamentals and applications of atomic scale nanocapillaries. Radha completed her PhD in 2012 in JNCASR, India following which she has worked in Northwestern University, USA before moving to Manchester in 2014. She has published 39 research papers including those in Nature and Science journals, and holds three patents. She was named as UNESCO L’Oréal-women in science fellow & international rising talent and was recognized as an inventor in MIT Technology Review’s “Innovators under 35” List in 2017. Affiliation: Condensed Matter Physics Group, The University of Manchester, Manchester M13 9PL, United Kingdom