Optofluidic integrated cell sorter fabricated by femtosecond lasers

Abstract

The main trend in optofluidics is currently towards full integration of the devices, thus improving automation, compactness and portability. In this respect femtosecond laser microfabrication is a very powerful technology given its capability of producing both optical waveguides and microfluidic channels. The current challenge in biology is the possibility to perform bioassays at the single cell level to unravel the hidden complexity in nominally homogeneous populations. Here we report on a new device implementing a fully integrated fluorescence-activated cell sorter. This non-invasive device is specifically designed to operate with a limited amount of cells but with a very high selectivity in the sorting process. Characterization of the device with beads and validation with human cells are presented.

Femtosecond laser fabrication of optofluidic devices for single cell manipulation

“…The geometry of the device is similar to the one already reported in the literature [9], where the channel roughness remained an issue since it hindered a good image quality. In order to overcome this limitation we fabricate the microfluidic channels parallel to the writing beam by irradiating them from the bottom to the top of the substrate, as schematically shown in Fig.…”

“…In particular, the microfluidic network was created by fs laser irradiation followed by chemical etching (FLICE) and the waveguide just by fs laser irradiation, with parameters previously reported [9]. The complete device obtained after the irradiation and etching procedure is shown in Fig.…”

Optofluidics for handling and analysis of single living cells

“…So that, the combination of OT in microfluidic systems attracted a growing interest, as it gives born to devices for biological analysis with enhanced sensitivity [10,11] and additionally new measurement techniques for cell biology8. This gives an important impact in biotechnological research in the direction of the realization of microfluidic flow cytometers [12,13] and cell sorters [11,14]. In fact, the sensitivity of measurements requiring long integration times, as when collecting Raman scattering [15] or cell fluorescence with a very low expression of the stained molecules will be enhanced by stabilizing the sample position.…”

“…An alternative solution consists in integrating vertical-cavity surface-emitting lasers (VCSEL) or GaAl/AlGaAs heterostructures that are able to trap and move microspheres and biological samples in microfluidic systems [19], however the complexity to fabricate these devices and low tenability of power limit their use. Recently counter propagating beams, properly faced on microfluidic channels through integrated waveguides fabricated on a glass substrate, were reported [14,20]. This approach was used also to realize fluorescence-activated optical-sorting of cells.…”

Hydrodynamic lift for single cell manipulation in a femtosecond laser fabricated optofluidic chip

“…The design is based on an X-shaped channel, similarly to what already presented in [9,21]: two input channels merge in a central section, where optical investigation and sorting can be performed, which then separates into two output channels for sample collection and waste. Here we rotated the two input channels by 90°, so as to exploit the bottom channel as a buffer to lift the upper stream containing the sample.…”