  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.

Instrumentation and Detectors;Image and Video Processing;Optics