Synergistic action in colloidal heat engines coupled by non-conservative flows

Area of Science:

• Thermodynamics
• Mesoscale physics
• Colloidal science

Background:

• Colloidal heat engines are typically studied using conservative potentials and in isolation.
• Biological micromotors often operate beyond these idealized conditions, involving non-conservative forces and interactions.

Purpose of the Study:

• To investigate thermodynamics beyond idealizations by examining colloidal heat engines at close separation.
• To understand the impact of non-conservative scattering forces and cooperative behavior on engine performance.

Main Methods:

• Constructed a pair of colloidal engines using two microspheres in optical traps at close separation.
• Developed a minimal theoretical model, analogous to active Brownian particles, to estimate thermodynamic quantities.

Main Results:

• Demonstrated that non-conservative scattering forces significantly affect particle motion at close proximity.
• Showed that hindered hydrodynamics lead to energy reuse, driving particles out of equilibrium and enabling cooperative energy exchange.
• Results indicate that closely spaced Stirling engines outperform widely separated ones.

Conclusions:

• Cooperative behavior in closely spaced colloidal engines enhances performance compared to isolated systems.
• The findings provide insights for designing larger, biologically inspired collections of mesoscale engines.
• Further theoretical development is needed for a complete understanding of these complex systems.