Experimental Verification of Intrinsic Pressure Framework in an Activity Landscape

The intrinsic pressure framework, which treats self-propelling force as an external force, provides a convenient and consistent description of mechanical equilibrium in active matter. However, direct experimental evidence is still lacking. To validate this framework, here we employ a programmable robotic platform, where a single light-controlled wheeled robot travels in an activity landscape. Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force. This result unambiguously confirms the theoretical predictions, thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.