Igor Mastikhin

I apply Magnetic Resonance methods to studies of materials and processes with short signal lifetimes. I am interested in two areas of NMR and MRI applied to materials science: portable NMR instrumentation/applications and two-phase media.

1. My research interests are in the development of portable, unilateral NMR instruments with controlled parameters (sensitive volume size and location, magnetic field gradient) (in collaboration with Drs. B.J.Balcom and B.Newling), and how to use them to measure various interesting and useful things.

   Recently, we investigated how to measure viscous and elastic properties of a sample with portable NMR. In MR elastography, NMR signal is sensitized to vibrations by synchronizing the vibrations with the oscillating magnetic field gradients. In the most basic portable NMR, magnetic field gradients are permanent: you just do measurements in the presence of a stray field of an array of permanent magnets, so you don't really have control over the gradients per se. You can, however, control the spin phase by flipping it with RF pulses, so we generated an "effective" square-wave gradient, a la Stepisnik-Callaghan, by using the CPMG 180-pulse train. We show (Selbi et al, JMR 2022) that we can reliably extract information on viscoelastic sample properties with NMR, and, unlike the conventional MR elastography where you need a big MRI scanner, the NMR sensor can fit into your palm.

   But we can do better than that. If there is a distribution of velocities in a sample induced, for example, in a Couette cell, we can use the resulting phase interference to measure the sample’s flow index. Again, such a measurement can be performed with a portable NMR instrument (Selby et al, JMR, 2022).

2. Two-phase media (microbubbles, microdroplets) and how to measure them quantitatively with MRI: MRI can be sensitive to a wide variety of physical and chemical parameters. Both a spatially resolved mapping of the medium (if you do MRI, preferably a single-point based one) and a fast bulk measurements can be performed. Our MRI studies of spray show that you can investigate very fast flows both inside a spray nozzle (where optical methods are inapplicable due to the lack of transparency) and in the atomization region noninvasively and quantitatively.

In addition to that, we just started research in MRI of freezing sprays. When droplets of water become supercooled, a so-called “freezing rain” takes place, covering any cold surface with a layer of ice. This is a common winter phenomenon in Atlantic Canada and in other regions with frigid winter temperatures. Its close relative is a freezing sea spray where wind-blown droplets of seawater accumulate on vessels, lighthouses and any maritime structures. Ice has very short NMR signal lifetimes and thus is very hard to detect by conventional NMR instruments. However, there is a considerable amount of unfrozen concentrated saline solution – brine – inside the ice. We attempt to gain more information about the ice microstructure and formation dynamics by measuring NMR signal from the brine (Wilbur et al, JMR 2020).

Considering how unwieldy an MRI scanner would be for a field measurement, we explored possibilities of a portable NMR for such a measurement. With it, we can detect changes in small concentrations of brine in ice at different temperatures, spraying regimes and a surface orientation (Ahmadi et al, JMR 2022).

Selected publications

Selby, W., Garland, P., and Mastikhin, I. "A Simple Portable Magnetic Resonance Technique for Characterizing Circular Couette Flow of Non-Newtonian Fluids", Journal of Magnetic Resonance (2022) 345, 107325.

Selby, W., Garland, P., and Mastikhin, I. "Dynamic Mechanical Analysis with Portable NMR", Journal of Magnetic Resonance (2022) 339, 107211.

Ahmadi, S., Aguilera, A.R., MacMillan, B., and Mastikhin, I. "Studies of Periodic Seawater Spray Icing with Unilateral NMR", Journal of Magnetic Resonance (2022) 334, 107109.

Grant Wilbur, Bryce MacMillan, Kyle M. Bade, Igor Mastikhin. “MRI monitoring of sea spray freezing”, Journal of Magnetic Resonance (2020) 310, 106647.

Adair, A., Mastikhin, I.V., Newling, B."Motion-Sensitized SPRITE Measurements of Hydrodynamic Cavitation in Fast Pipe Flow", Magnetic Resonance Imaging (2018) 49, 71-77.

I.V.Mastikhin, K.Bade, S.Ahmadi, K.Bade, A rapid magnetization preparation for MRI measurements of sprays, J. MAGN RESON (2017) 283, 52-60.

I.V.Mastikhin, A.Arbabi, K.Bade, Magnetic Resonance Imaging measurements of a water spray upstream and downstream of a spray nozzle exit orifice, J.MAGN.RESON (2016) 266, 8-15.