Introduction

The optofluidic device developed allows light-sheet fluorescence microscopy to be performed on a millimeter-sized glass chip. Samples are selectively excited as they flow through the channel in sequence, allowing their images to be reconstructed in 3D. The device can be used as an add-on to a conventional microscope, requires no alignment of the light sheet on the flowing sample, and allows for high measurement rates.

Technical features

The light sheet fluorescence microscopy technique allows to reconstruct 3D images with high spatial resolution and minimal phototoxic damage on the samples under examination. A limitation of this technique is the measurement rate, as only one sample at a time can be measured by inserting and aligning it in a suitable support. The device (a functioning prototype), built using a femtosecond laser micro-fabrication technique, includes one or more cylindrical optofluidic lenses with an engineered profile to obtain an aberration-free illumination plane crossing the microfluidic channel. Biological samples are circulated via a microfluidic pump and observed with a traditional microscope. No user alignment procedure is required, thus enabling fast and automatic three-dimensional scanning of the sample. A high-throughput system with a high acquisition rate (> 1 sample/s, demonstrated on intact cell spheroids, 250 µm in diameter acquiring 100 frames per sample).

Possible Applications

• Optical Microscopy;
• Cell morphology or cell aggregates in 3D study;
• Analysis of nuclear and subnuclear markers;
• High throughput screening of biological samples;
• Drug efficacy monitoring.

Advantages

• Compact and portable: can be used as add-on in commercial upright or inverted microscopes without the need of any motorised stage;
• Versatile fluidic design: can image samples at different spatial scales, from single cells to organoids or embryos;
• Versatile optical design: suitable for multiple sided illumination, multicolour excitation and double sided detection;
• High-throughput: high acquisition rate (> 1 sample/s demonstrated on intact 250 µm diameter cellular spheroids and 100 frames/sample);
• Modular: easy integration of multiple lab-on-chip functionalities.