Ptychographic sensor for large-scale lensless microbial monitoring with high spatiotemporal resolution

TL;DR

This paper introduces a ptychographic sensor capable of lensless, high-resolution, large-scale microbial monitoring with rapid temporal resolution, enabling detailed observation of bacterial growth and drug effects in resource-limited settings.

Contribution

The study presents a novel integrated ptychographic sensor with a temporal-similarity constraint, achieving high spatiotemporal resolution and large field of view for microbial analysis.

Findings

Achieves 488 nm spatial resolution and 15-second temporal resolution.

First direct observation of bacterial growth in 15 seconds.

Demonstrates rapid bacterial detection and antibiotic susceptibility testing.

Abstract

Traditional microbial detection methods often rely on the overall property of microbial cultures and cannot resolve individual growth event at high spatiotemporal resolution. As a result, they require bacteria to grow to confluence and then interpret the results. Here, we demonstrate the application of an integrated ptychographic sensor for lensless cytometric analysis of microbial cultures over a large scale and with high spatiotemporal resolution. The reported device can be placed within a regular incubator or used as a standalone incubating unit for long-term microbial monitoring. For longitudinal study where massive data are acquired at sequential time points, we report a new temporal-similarity constraint to increase the temporal resolution of ptychographic reconstruction by 7-fold. With this strategy, the reported device achieves a centimeter-scale field of view, a half-pitch spatial resolution of 488 nm, and a temporal resolution of 15-second intervals. For the first time, we report the direct observation of bacterial growth in a 15-second interval by tracking the phase wraps of the recovered images, with high phase sensitivity like that in interferometric measurements. We also characterize cell growth via longitudinal dry mass measurement and perform rapid bacterial detection at low concentrations. For drug-screening application, we demonstrate proof-of-concept antibiotic susceptibility testing and perform single-cell analysis of antibiotic-induced filamentation. The combination of high phase sensitivity, high spatiotemporal resolution, and large field of view is unique among existing microscopy techniques. As a quantitative and miniaturized platform, it can improve studies with microorganisms and other biospecimens at resource-limited settings.