# Universal optimal geometry of minimal phoretic pumps

## TL;DR

This paper reveals that the optimal design for minimal phoretic pumps, which use chemically active patches to generate flow, is universal and does not depend on specific chemical properties.

## Contribution

It identifies the universal optimal arrangement of three chemical patches in minimal phoretic pumps, advancing understanding of their design principles.

## Key findings

- Optimal patch arrangement maximizes flow rate.
- Universal design independent of chemical specifics.
- Provides guidelines for efficient phoretic pump construction.

## Abstract

Unlike pressure-driven flows, surface-mediated phoretic flows provide efficient means to drive fluid motion on very small scales. Colloidal particles covered with chemically-active patches with nonzero phoretic mobility (e.g. Janus particles) swim using self-generated gradients, and similar physics can be exploited to create phoretic pumps. Here we analyse in detail the design principles of phoretic pumps and show that for a minimal phoretic pump, consisting of 3 distinct chemical patches, the optimal arrangement of the patches maximizing the flow rate is universal and independent of chemistry.