(4cg) A Dynamical Systems Approach to Active Matter Design and Control

Research Interests: Active matter represents a broad class of materials comprising interacting and energy-consuming constituents. Systems ranging from cytoskeletal proteins to bird flocks share the ability to spontaneously manifest collective behaviors on time and length scales much larger than the individual agents. My research tackles the inverse problem of rationally designing soft, active matter systems and their inputs to exhibit desired spatiotemporal dynamics. In soft robotics, these dynamics might be the end goal. Alternatively, material flows created by active materials can drive the creation of structures inaccessible through equilibrium assembly.

My research investigates the use of exogenous control through optimal control theory and, recognizing the need for programmable materials to be untethered from hardware, endogenous control via engineered reaction-diffusion systems that couple to chemomechanics. In the latter case, my group will utilize machine learning techniques to identify the reaction pathways needed to achieve the desired dynamics. I take this approach because, in contrast to human-made machines, when the machine is itself a material, regulation must come within. Developing internal feedback loops for active materials, in the form of reaction pathways, is a grand challenge in active matter research and essential for unlocking the dynamical diversity and complexity needed for applications.

As a proof of concept, my poster focuses on a computational study of a photoactivatable active nematic liquid crystal system that exhibits multiple dynamical attractors. I demonstrate that the system can be toggled between these attractors by spatiotemporally varying the strength of the active stress in the material. Going forward, I aim to expand the approach to living systems, such as optogenetically enabled tissues and bacterial colonies.

I am Co-Investigator on a recently funded DOE project "Dynamics and control of active nematics using nonlinear reduced-order models" (Basic Energy Science, Biomolecular Materials program), which supports this work. The project grew out of my work as a postdoc at Brandeis University (2015-2019), but was developed independently of my former mentors through my collaboration with Piyush Grover (PI, UN-L) and Jae Sung Park (Co-I, UN-L).

Put broadly, this effort focuses on understanding the principles of self-organizing materials. As a faculty member, I will also pursue fundamental biological research by teaming up with experimental collaborators. Towards establishing those connections, I recently joined the Physics Department at Rochester Institute Technology (6/15/2021) as a Research Scientist to study bacterial chromatin under Moumita Das (NSF "Decoding the Rules of Phase Separation in Bacterial Chromatin"), which I am pursuing concurrently with my DOE project. I am seeking a faculty position in a department that will allow me to grow an interdisciplinary lab that conducts research at the interface of physics, materials science, biology, and nonlinear dynamics.

Selected Publications:

1. I. Hunter*, M. M. Norton*, B. Chen, C. Simonetti, M. E. Moustaka, J. Touboul, and S. Fraden. Pattern Formation in a 4-Ring Reaction-Diffusion Network with Heterogeneity. Submitted 2021. arXiv:2101.10434. *Equal Contribution.
2. M. M. Norton, P. Grover, M.F. Hagan, and S. Fraden, "Optimal Control of Active Nematics," Physical Review Letters, 2020. Editor's Suggestion.
3. M. M. Norton*, N. Tompkins*, M. C. Cambria, J. Held, and S. Fraden. "Dynamics of Reaction-Diffusion Oscillators in Star and other Networks with Cyclic Symmetries Exhibiting Multiple Clusters," Physical Review Letters, 2019. *Equal Contribution.
4. A. Opathalage*, M. M. Norton*, M. Juniper, B. Langeslay, S. A. Aghavmi, S. Fraden, and Z. Dogic, Z., "Self-organized dynamics and the transition to turbulence of confined active nematics," PNAS, 2019, *Equal Contribution.
5. M. M. Norton, A. Baskaran, A. Opathalage, B. Langeslay, S. Fraden, A. Baskaran, and M. F. Hagan, "Insensitivity of active nematic liquid crystal dynamics to topological constraints," Physical Review E, 2018. Editor's Suggestion.
6. M. M. Norton, R. J. Robinson, and S. J. Weinstein, "Model of ciliary clearance and the role of mucus rheology," Physical Review E, 2010.

Teaching Interests: My research plan is interdisciplinary and will attract students and postdocs with interests ranging from fluid dynamics and transport phenomena to nonlinear dynamics, physics, control theory, and biology. I aim to equip students of all levels that come through my lab with fundamental skills they can apply throughout their careers. My background in Mechanical Engineering (BS, MS, Ph.D.) equips me to teach core courses: fluid dynamics, transport phenomena, and thermodynamics. Additionally, I would also like to develop an elective course focused on the intersection of dynamical systems and biology. I am an active mentor in all labs that I have been a part of; I share authorship in most recent papers with graduate and undergraduate students and have advised Honors students on their theses. As a faculty member, I will build on this experience and cultivate a sense of community through journal clubs and informal presentations that encourage cross-talk across labs and departments.