What physical processes govern the movement of microscopic structures capable of interacting with their environment? The answer lies in two mechanisms: self-propulsion, to escape unfavorable locations; and slow diffusion, to move toward more advantageous ones. This is the finding of scientists Jacopo Romano and Andrea Gambassi from SISSA-Scuola Internazionale Superiore di Studi Avanzati in their new study published in Physical Review Letters.

In their work, the researchers combined computer simulations with mathematical calculations, taking inspiration from nature. It is well known that feedback-driven motion underlies the behavior of various microorganisms, which analyze incoming and outgoing signals and adapt their direction of movement accordingly. The study reproduces the physical behavior of natural and synthetic agents in two distinct scenarios: when a specific destination must be avoided based on signals, and when it must instead be reached.

The researchers found that in the first case, a process of “superdiffusion” occurs, with accelerated motion, while in the second case a subdiffusive process takes place, with much slower movement. These findings provide important insights for the design of smart particles capable of moving at the microscale, with potential applications in medicine, particularly for more efficient drug delivery.