(6ff) Laboratory of Interfaces, Flow and Electrokinetics (LIFE)

Interfaces, by definition, are responsible for heterogeneity in materials that in turn gives rise to critical properties like surface tension, wetting, colloid-colloid interactions and many others. My group will study interfacial phenomena of liquid-liquid, liquid-solid and liquid-liquid-solid interfaces coupled with multiphase flow and ion transport. The overarching goal of my group is to utilize the expertise in interfacial science for applications in personal care, food science, enhanced oil recovery, and energy storage. More specifically, I will focus on the following research directions:

(1) Advanced nanoemulsions: Nanoemulsions are nano-sized droplets of oil suspended in water or vice-versa. Due to their small size, nanoemulsions provide an efficient way to deliver hydrophobic nutrients, be it orally or topically, by dissolving the nutrients in the oil phase. In my group, we will develop techniques that are specifically tailored to create double nanoemulsions, i.e. nanodroplets inside nanodroplets (oil-in-water-in-oil and water-in-oil-in-water nanoemulsions). Furthermore, we will design energy friendly routes to create pickering nanoemulsions, i.e. nanoemulsions stabilized by particles. The pickering emulsions are attractive since they do not rely on harsh surfactants and instead utilize the particles for stabilizing emulsions. Our efforts will advance food science and personal care research through the formulation of ready-to-use therapeutic food as well as functional skin care products. To this end, we plan to collaborate with expert nutritionists and dermatologists to develop relevant and stable formulations.

Prior work: During my doctoral research under Prof. Patrick S. Doyle and Prof. T. Alan Hatton at MIT, I proposed and experimentally validated new scaling relations to predict average droplet size of nanoemulsions. I also built a general platform to prepare nanoemulsions using energy friendly routes and demonstrated their utility in nano-hydrogel synthesis and in efficient hydrophobic drug dissolution.

(2) Flow in porous media: Despite the fact that the crude oil sources are rapidly decreasing worldwide, it is estimated that only 20 – 40% oil is recovered from the oil fields. Therefore, recovery of the trapped oil from the oil fields is crucial for our mounting energy needs. In my group, we will study the evolution of oil-water interface past different geometric features such as array of different-shaped obstacles and/or bifurcations. Specifically, we will explore the effects of wetting and relative viscosity by developing invasion-percolation algorithms and multiphase-flow simulators. In addition to the oil recovery applications, these results will also of value in micro-reactor design, flow inside lungs, and for trapping / releasing drops inside microfluidic devices. We will also collaborate with leading scientific groups that study flow in porous media experimentally to validate and strengthen our theoretical capabilities.

Prior work: During my doctoral research, I examined formation of liquid pockets during immiscible liquid-liquid displacement over an obstacle / patterned wall where I theoretically predicted the criterion for entrapment. The theoretical predictions were validated through microfluidic experiments performed by a collaborator.

(3) Electrokinetics for energy and the environment: Electrochemical capacitors, or supercapacitors, are an active area of research since they are useful in high power applications such as in trains and elevators. My group will develop theoretical and experimental tools to investigate the effects of electrolyte choices (including flowable electrodes) on the charging and discharging of supercapacitors. We will also study electrokinetic remediation, i.e. the process where toxic waste is removed by applying a voltage, with an emphasis on the effect of surfactants on ion transport.

Prior work: In my post-doctoral position with Prof. Howard Stone at Princeton University, I developed general relations for charge storage and capacitance for asymmetric electrolytes near a charged surface. I am currently conducting experiments to validate these results for use in supercapacitor applications. Furthermore, I am also investigating the utility of bi-disperse carbon suspensions for flowable supercapacitors.

Teaching Interests:

I am passionate about teaching and have had several teaching responsibilities such as instructor for special topics in graduate fluid mechanics (Princeton), instructor for undergraduate fluid mechanics (MIT), teaching assistant for undergraduate heat and mass transfer (MIT), and instructor of high school physics and mathematics (iitjeelectures.com). My philosophy while teaching a course is to provide students with multiple learning opportunities. I like to engage them through short conceptual quizzes, supplementary video lectures to clarify recurring questions (sample from my course at MIT here: http://bit.ly/2tN87UX), and in general promoting an interactive class environment. I am prepared to teach the following courses in future: (a) undergraduate / graduate fluid mechanics (b) undergraduate / graduate heat and mass transfer and (c) undergraduate reaction engineering.

Selected publications:

• Badruddoza, A.Z M,* Gupta, A.*, Myerson, A.S., Trout, B.L., and Doyle, P.S. (2018), Advanced Therapeutics, 2018
• Gupta, A.*, Lee, H.*, & Doyle, P. S. (2017), Physical Review Fluids, 2, 094007.
• Gupta, A.*, Badruddoza, A. Z. M*, & Doyle, P. S. (2017), Langmuir, 33, 7118-7123.
• Lee, H.*, Gupta, A.*, Hatton, T. A., & Doyle, P. S. (2017), Physical Review Applied, 7(4), 044013.
• Gupta, A., Narsimhan, V., Hatton, T. A., & Doyle, P. S. (2016), Langmuir, 32(44), 11551-11559.
• Gupta, A., Eral, H. B., Hatton, T. A., & Doyle, P. S. (2016), Soft Matter, 12(11), 2826-2841
• Gupta, A., Eral, H. B., Hatton, T. A., & Doyle, P. S. (2016), Soft Matter, 12(5), 1452-1458.
• Gupta, A., & Roy, S. (2013), Chemical engineering journal, 225, 818-836.

* denotes equal contribution