Fluorescence microscopy imaging with a Fresnel zone plate array based optofluidic microscope

Abstract

We report the implementation of an on-chip microscope system, termed fluorescence optofluidic microscope (FOFM), which is capable of fluorescence microscopy imaging of samples in fluid media. The FOFM employs an array of Fresnel zone plates (FZP) to generate an array of focused light spots within a microfluidic channel. As a sample flows through the channel and across the array of focused light spots, the fluorescence emissions are collected by a filter-coated CMOS sensor, which serves as the channel's floor. The collected data can then be processed to render fluorescence microscopy images at a resolution determined by the focused light spot size (experimentally measured as 0.65 μm FWHM). In our experiments, our established resolution was 1.0 μm due to Nyquist criterion consideration. As a demonstration, we show that such a system can be used to image the cell nuclei stained by Acridine Orange and cytoplasm labeled by Qtracker®.

Cell phones go cellular—Current scale‐down lab‐in‐your‐pocket applications

“…In this optofluidic microscope design principle, the aperture array can also be replaced by a Fresnel zone plate array in the coverslip over the microfluidic channel. Resolution is determined by the focus spot size of the Fresnel zone plates (10). The reintroduction of these diffractive elements no longer makes this implementation lensless, but their quasi-twodimensional nature still aids the miniaturization goal.…”

A perspective on optical developments in microfluidic platforms for Caenorhabditis elegans research

“…Optofluidic microscopes developed so far have relied on bringing the sample as close as possible to the detector. [74][75][76][77][78] They circumvent the use for an expensive optomechanic structure and expensive optics (as in conventional microscopes), and thus could be much more cost-effective and compact.…”

“…74 A more sophisticated technology using submicron multi-apertures between the microchannel and the CMOS chip uses algorithms to rebuild an image of a worm flowing above the mask and increases the resolution up to 0.8 lm. [75][76][77] The last strategy uses coherent inline holography and pixel super-resolution to create high-resolution amplitude and phase images with a comparable resolution (Fig. 2(d)).…”

Optofluidic ultrahigh-throughput detection of fluorescent drops

“…be applied to increase the SNR of fluorescence detection, such as by incorporating lens arrays to focus the excitation light onto the drops, 17,20 by using filter materials with higher rejection ratio between the excitation and emission wavelengths, by using a stronger light source, or by introducing spatial modulation methods. 26 …”

“…Previously, this design has been used in an optofluidic microscope along with Fresnel zone plate array for the fluorescence imaging of cells at a spatial resolution of 1 μm. 20 Since the diameter of drops used in droplet microfluidics applications are typically on the order of tens to hundreds of micrometers, no high resolution imaging is necessary for the enumeration of fluorescent drops.…”