Research Initiation Award: Thermodynamic Phase Separation in a Living, Active Matter System

Research Initiation Awards provide support for faculty at Historically Black Colleges and Universities who are building a research program. It is expected that the award helps to further the faculty member's research capability and effectiveness, improves research and teaching at his home institution, and involves undergraduate students in research experiences. The award to North Carolina Agricultural and Technical State University has potential broader and societal impact in a number of areas. The project seeks to investigate the dynamics of active matter systems. The research crosses the fields of mathematics, physics, and biology. Undergraduate students will gain research experiences and the research will be integrated in a number of biophysics courses. The project will also contribute to the development of a Biological Physics Concentration at the university.

Unlike ensembles traditionally discussed in Statistical Mechanics research, active matter systems consist of objects that consume energy and propel themselves, and thus are never in equilibrium. Building on the discovery of bull sperm collective dynamics in viscoelastic fluids, this project focuses on using experiments to quantify and understand the phenomenology of phase separation in active matter systems. The primary objective of this project is to map out the coexistence curve of clustered and isolated phases. The research goal will be approached by two methods: a 'pressure' based method that involves building a microfluidic device to increase cell density, and a 'temperature' based method, in which the relative strengths of alignment and randomizing factors are tuned by changing fluid properties. Findings from this project will answer fundamental thermodynamics questions, such as how to quantify parameters like pressure or temperature in a living active matter system, and how to formulate an equivalent equation of state. Moreover, since viscoelastic fluids are naturally present in the mammalian female reproductive tract, this project would also help to understand the regulation and mechanisms of sperm movement. The results provide underlying basic science knowledge that could potentially be used to improve animal husbandry.