Bacterial Footprints in Elastic Pillared Microstructures

TL;DR

This study shows that micropillared microstructures can detect motile bacteria through deformation patterns caused by bacterial suspensions, enabling visual identification of specific microorganisms.

Contribution

It introduces a novel method for detecting motile bacteria using elastic micropillar arrays that deform upon bacterial suspension evaporation.

Findings

Motile bacteria with flagella induce micropillar bending.

Deformation patterns are characteristic and visually identifiable.

The method can distinguish specific bacterial strains based on motility.

Abstract

Soft substrates decorated with micropillar arrays are known to be sensitive to deflection due to capillary action. In this work, we demonstrate micropillared epoxy surfaces are sensitive to single drops of bacterial suspensions. The micropillars can show significant deformations upon evaporation, just as capillary action does in soft substrates. The phenomenon has been studied with five bacterial strains S. epidermidis, L. sakei, P. aeruginosa, E. coli and B. subtilis. The results reveal that only droplets containing motile microbes with flagella stimulate micropillar bending, which leads to significant distortions and pillar aggregations forming dimers, trimers, and higher order clusters. Such deformation is manifested in characteristic patterns that are left on the microarrayed surface following evaporation, and can be easily identified even by the naked eye. Our findings could lay the ground for the design and fabrication of mechanically responsive substrates, sensitive to specific types of microorganisms.