Pump-less static microfluidic device for analysis of chemotaxis of Pseudomonas aeruginosa using wetting and capillary action

• Novel pump-less microfluidic approach for the analysis of bacterial chemotaxis is proposed.
• Wetting and capillary action control diffusion of chemical and manipulation of fluids.
• The method can identify chemotactic behaviors of attraction, repellence, and binary motions.

Bacterial chemotaxis is a complex response to temporal changes of concentrations of chemoeffectors. Conventional methods, including microfluidic approaches, for the precise analysis of bacterial chemotaxis are limited in the accurate control of chemical gradients, low sensitivity, and longer analytical times although the advances in microfluidic technology provide a novel platform. Here, we present a diffusion-based microfluidic device to provide rapid diffusion of chemoeffectors using a liquid–liquid interface, which is a critical advance in the analysis of bacterial chemotaxis. The microfluidic method can rapidly analyze attractants and repellents, achieving a chemotaxis index corresponding to the concentrations and types of chemoeffectors. Moreover, we find that the dynamic switch in bacterial chemotaxis from attraction to repellence in response to specific chemoeffectors occurs in a concentration-dependent manner. Thus, our microfluidic method is promising and reliable for the analysis of bacterial chemotaxis.