Lensless Imaging Method Tracks Living Cells Inside the Incubator

Tampere University researchers have developed a new lensless imaging method that generates precise quantitative data on living cells from a single image, using a compact system that fits inside a standard cell-culture incubator. The method, called SF-PULSE, combines an AI-based neural network with physics-informed image reconstruction, and its compact design allows cells to be monitored continuously for hours or even days without staining or repeated removal from the incubator for imaging.

Quantitative phase imaging allows researchers to observe living, transparent cells without staining, while also providing quantitative information on features such as cell growth, size, and changes in biomass. The team set out to address two major limitations of the technique: conventional quantitative phase imaging systems are typically large and complex, making them poorly suited to long-term monitoring inside an incubator, and recovering phase information in lensless systems is a difficult computational problem that has traditionally required multiple images or additional optical components.

“Our SF-PULSE method can reconstruct quantitative phase information from a single measurement image without the need for complex optical hardware. The method reduced computational errors, improved reconstruction stability and enabled accurate long-term tracking of individual cells,” says Igor Shevkunov, first author of the study published in Applied Physics Letters.

This capability matters because it enables long-term, uninterrupted, and label-free monitoring of large numbers of cells, producing quantitative information about the behavior of individual cells rather than only the average behavior of a population. “Importantly, researchers can follow not only how a cell population changes, but also how individual cells grow, move, divide, and gain or lose biomass over time. This is often more informative than examining the average behavior of a cell population alone,” says co-author Meenakshisundaram Kandhavelu.

Beyond serving as another imaging modality, SF-PULSE has the potential to support entirely new types of biological experiments, including drug-response studies, toxicity screening, and investigations of cell-death mechanisms. Because the system is compact, lensless, and capable of monitoring hundreds or even thousands of cells simultaneously across a wide field of view, it could also be applied to automated biological analytics and the development of new biomedical instrumentation in the future.