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ACMD Seminar: The Countoscope: measuring self and collective diffusion with fancy counting

Brennan Sprinkle
Assistant Professor, Applied Math & Stats. Dept., Colorado School of Mines

Tuesday, November 28, 2023, 3:00-4:00 PM ET (1:00-2:00 PM MT)

A video of this talk will be made available to NIST staff in the Math channel on NISTube, which is accessible from the NIST internal home page. It will be taken down from NISTube after 12 months at which point it can be requested by emailing the ACMD Seminar Chair.

Abstract: Modern microscopy techniques can image complex, microscopic systems with an unprecedented resolution – but methods to analyze these images are much less robust. Available techniques rely on reconstructing and analyzing particle trajectories which can be difficult or impossible in dense, heterogeneous systems, or when particles frequently flux through the finite field of view. Inspired by the early work of Smoluchowski we introduce the `Countoscope’, a technique that near completely ameliorates the issues with trajectory-based techniques by simply dividing images into observation boxes and counting the number particles in each box. We show that by analyzing the statistical properties of particle number fluctuations in observation boxes of varying sizes, we can `zoom’ in or out to measure individual or collective particle kinetics. Using colloidal suspensions as a test case, we employ a combination of experiments, simulations, and analytical theory to support our findings. The `Countoscope’ is a potent tool to interrogate soft matter systems, and it has great potential to measure these systems both in and out of equilibrium.

Bio: Brennan Sprinkle is a an Assistant Professor of Applied Mathematics at the Colorado School of Mines, in Golden, CO. Dr. Sprinkle received is B.S. and M.S. in Applied Mathematics from the Colorado School of Mines in 2011 and 2013, respectively. He received his Ph.D in applied mathematics from Northwestern University in 2018. From 2018 to 2022, he was a postdoctoral researcher and Courant instructor at the Courant Institute of Mathematical Sciences at New York University. His research interests include designing numerical simulation tools to study problems in soft matter physics and fluid dynamics.

Host: Zach Grey

Note: This talk will be recorded to provide access to NIST staff and associates who could not be present to the time of the seminar. The recording will be made available in the Math channel on NISTube, which is accessible only on the NIST internal network. This recording could be released to the public through a Freedom of Information Act (FOIA) request. Do not discuss or visually present any sensitive (CUI/PII/BII) material. Ensure that no inappropriate material or any minors are contained within the background of any recording. (To facilitate this, we request that cameras of attendees are muted except when asking questions.)

Note: Visitors from outside NIST must contact Meliza Lane at least 24 hours in advance.


Created November 14, 2023, Updated June 11, 2024