Optofluidic ptychography on a chip

TL;DR

This paper introduces a fully integrated on-chip lensless microscopy method called optofluidic ptychography, enabling high-resolution imaging of flowing biological specimens with potential applications in biomedical diagnostics.

Contribution

It presents a novel on-chip ptychographic microscopy system that combines microfluidics and diffraction imaging for real-time, high-resolution biological specimen analysis.

Findings

Achieved 550 nm resolution with a 1.85-micron pixel sensor.

Successfully imaged C. elegans, yeast, paramecium, and closterium.

Operates at 30 frames per second for real-time imaging.

Abstract

We report the implementation of a fully on-chip, lensless microscopy technique termed optofluidic ptychography. This imaging modality complements the miniaturization provided by microfluidics and allows the integration of ptychographic microscopy into various lab-on-a-chip devices. In our prototype, we place a microfluidic channel on the top surface of a coverslip and coat the bottom surface with a scattering layer. The channel and the coated coverslip substrate are then placed on top of an image sensor for diffraction data acquisition. Similar to the operation of flow cytometer, the device utilizes microfluidic flow to deliver specimens across the channel. The diffracted light from the flowing objects is modulated by the scattering layer and recorded by the image sensor for ptychographic reconstruction, where high-resolution quantitative complex images are recovered from the diffraction measurements. By using an image sensor with a 1.85-micron pixel size, our device can resolve the 550 nm linewidth on the resolution target. We validate the device by imaging different types of biospecimens, including C. elegans, yeast cells, paramecium, and closterium sp. We also demonstrate high-resolution ptychographic reconstruction at a video framerate of 30 frames per second. The reported technique can address a wide range of biomedical needs and engenders new ptychographic imaging innovations in a flow cytometer configuration.