Sensing, analysis and manipulation of fluids and particles in confined spaces.
Pipettes and Aspiration
We have installed a facility for precise measurement of ionic currents passing through glass pipettes with opening diameters from tens of nanometers upwards. This facility has been used to develop an analytical method, aspiration, in which the mechanical properties of micro- and nanoscale soft particles are studied using optical and electrical data [1,2]. This research builds on previous work on tunable resistive pulse sensing (TRPS) using elastomeric pores [3,4].
Modelling Nanofluidic Transport
Understanding nanofludic transport is a common theme in our studies using pores and pipettes. Fluids and particles are driven through and around nanoscale structures by pressure, electrophoresis, electro-osmosis, dielectrophoresis, Brownian motion – and even magnetism, in the case of magnetic beads. We have studied nanofluidic transport using theory and finite element simulations in order to understand TRPS experiments , and we are extending this work to aspiration experiments.
 Gangotra, A., Biviano, M., Dagastine, R. R., Berry, J. D. & Willmott, G. R. Use of microaspiration to study the mechanical properties of polymer gel microparticles. Soft Matter 15, 7286-7294 (2019).
 Gangotra, A. & Willmott, G. R. Mechanical Properties of Bovine Erythrocytes Derived from Ion Current Measurements Using Micropipettes. Bioelectrochemistry 128, 204-210 (2019).
 Willmott, G. R. Tunable Resistive Pulse Sensing: Better Size and Charge Measurements for Submicrometer Colloids. Anal. Chem. 90, 2987-2995 (2018).
 Weatherall, E. & Willmott, G. R. Applications of Tunable Resistive Pulse Sensing. Analyst 140, 3318-3334, doi:10.1039/C4AN02270J (2015).
 Weatherall, E., Hauer, P., Vogel, R. & Willmott, G. R. Pulse Size Distributions in Tunable Resistive Pulse Sensing. Anal. Chem. 88, 8648-8656 (2016).