Francesca Bragheri

The combination of structured illumination and light sheet fluorescence microscopy in a microfluidic integrated platform enables high throughput super-resolution imaging.

Femtosecond laser micromachining is becoming an established fabrication technique for transparent material processing in three dimensions

Femtosecond laser micromachining is becoming an established technique for the fabrication of complex three-dimensional structures in glass. The combination of laser writing and chemical etching increases the technique versatility by allowing the fabrication of hollow structures within the bulk material. The possibility to encompass both optical and fluidic components in a single substrate allows us to realize optofluidic devices usable in several application fields. Here, we present new investigations of laser-assisted etching in Eagle XG glass showing good etching conditions at low repetition rates, where thermal effects can be neglected, and low irradiation speeds, which allow for complex microchannel network formation.

Single-cell analysis techniques are fundamental to study the heterogeneity of cellular populations, which is the basis to understand several biomedical mechanisms. Light-sheet fluorescence microscopy is a powerful technique for obtaining high-resolution imaging of individual cells, but the complexity of the setup and the sample mounting procedures limit its overall throughput. In our work, we present an optofluidic microscope-on-chip with integrated microlenses for light-sheet shaping and with a fluidic microchannel that allows the automatic and continuous delivery of samples of a few tens of microns in size. The device is used to perform dual-color fluorescence analysis and 3D reconstruction of xenograft-derived mouse breast cancer cells.

Optofludic lab-on-chips are compact microsystems that allow the manipulation, the analysis and the imaging of cells with high throughput even at the single cell level. The optofluidic microscopes on chip here presented are fabricated by femtosecond laser micromachining followed by chemical etching. The technique is ideally suited for rapid prototyping and allows 3D geometries and perfect alignment between microfluidic and optical components networks. The devices have been validated on cancer cell lines by imaging in three dimensions both clusters of cells growing on spheres and single cells.

Since the pioneering work of Ashkin and coworkers, back in 1970, optical manipulation gained an increasing interest among the scientific community. Indeed, the advantages and the possibilities of this technique are unsubtle, allowing for the manipulation of small particles with a broad spectrum of dimensions (nanometers to micrometers size), with no physical contact and without affecting the sample viability. Thus, optical manipulation rapidly found a large set of applications in different fields, such as cell biology, biophysics, and genetics. Moreover, large benefits followed the combination of optical manipulation and microfluidic channels, adding to optical manipulation the advantages of microfluidics, such as a continuous sample replacement and therefore high throughput and automatic sample processing. In this work, we will discuss the state of the art of these optofluidic devices, where optical manipulation is used in combination with microfluidic devices. We will distinguish on the optical method implemented and three main categories will be presented and explored: (i) a single highly focused beam used to manipulate the sample, (ii) one or more diverging beams imping on the sample, or (iii) evanescent wave based manipulation.

By using a model DNA hydrogel we show that the onset of non-Newtonian behavior can be fully understood on the basis of the connectivity of the network and the bond energy.

Two optofludic devices for the manipulation, analysis and imaging of cancer cells by laser light are presented. The chips are fabricated by femtosecond laser micromachining followed by chemical etching. The technique allows 3D geometries and perfect alignment between microfluidic and optical components networks. Both devices have been validated on cancer cell lines either by probing their mechanical properties at the single cell level or by imaging in three dimensions clusters of cells growing on spheres.