Keywords : Lab-on-chips, bioanalytical methods, microfluidics, translational medicine

Microfluidics-based microdevices are now steadily making their way as a major tool in biomedical research. They yielded particularly impressive applications in massively parallel technologies, such as digital sequencing, or as a key (and often unrecognized) component of next generation sequencing machines.

The penetration of microfluidics in the field of diagnosis is also proposing great promises, but it raises new challenges, notably the need to purify and extract analytes from complex matrices.

In this talk, we shall discuss the challenges raised by this need, and propose some solutions and applications, based on the use of magnetic particles as a common denominator.

The first technology, named EPHESIA, is dedicated to the sorting and multimodal typing of rare cells. It consists in self-assembling in a high throughput microfluidic device, an array of antibody-bearing magnetic particles. We shall then describe a new approach allowing to downscale the fluidized bed principle, as an alternative to affinity chromatography in miniaturized format.

We shall finally show how magnetic particles can also improve the power of droplet microfluidics, and drive this technology out of its current mainstream families of applications, allowing in particular complex and programmable analytical processes.

Acknowledgements : this work was supported in part by French PIA project IPGG (ANR-10-EQPX-34), European projects ERCadg Cello (FP7-IDEAS-ERC-321107), ERC-POC COMMiT, and  HoliFAB (H2020-NMBP-PILOTS-2017- 760927), and ANR PRCE DROMOS.

About the speaker : Jean-Louis. Viovy is Research Director Emeritus in UMR 168, (PhysicoChimie Curie), with multiple affiliations to Institut Curie, CNRS, PSL university and IPGG (Institut Pierre Gilles de Gennes for Microfluidics). He has been cofounder, with J. Prost and L. Leibler, of laboratory of theoretical chemical physics at ESPCI, and founded within the Institut Curie in 1996 the MMBM team (Macromolecules and Microsystems in Biology and Medicine) comprising about 25 researchers. In 2011, he co-founded IPGG with P. Tabeling. He was awarded the Bronze Medal of the CNRS (1983), the Polymer Prize of the French Chemical Society (1996), the Philip Morris Scientific Prize in 1996, two OSEO Entrepreneurship Awards in 2004 and 2005, and the Lifetime Achievement Award of American Electrophoresis Society in 2016. He is author or co-author of more than 300 articles and 30 patents. He was granted in 2013 an ERCadg funding on the topic of development of artificial organs. He was co-founder of the Chemical and Biological Microsystems Society, which organizes every year the MicroTAS conference. The beginning of his career was in polymer physics, and he switched in the 90’s to biophysics, analytical sciences and microfluidics. He was co-founder of two startups, Fluigent and Inorevia. His current interests are mainly in methodological development in microfluidics, involving in particular the development of tools based on magnetism, organs-on-chips and textile microfluidics.

Antiferromagnets (AF) are currently in the limelight thanks to recent breakthroughs demonstrating the efficient effect of spin currents in interacting with the AF order parameter. So far, due to the lack of net magnetization, controlling AF distributions has been rather challenging. Current-induced AF control also opens new perspectives in Terahertz magnetization dynamics. On the materials side, antiferromagnets represent most magnetic materials and some of them show several simultaneous coupled ordered phases. They are commonly called ‘multiferroics’. Multiferroic materials are the focus of an intense research effort due to the significant technological interest of multifunctional materials as well as the rich fundamental physics lying in the coupling of various order parameters. Among all multiferroics, BiFeO3 is a material of choice because its two ordering temperatures (ferroelectric FE and AF) are well above room temperature, in addition of showing one of the largest magnetoelectric coupling. One difficulty in handling multiferroics lies in the challenging assessment of their coupled FE/AF textures. Second harmonic generation (SHG) has proven to be a powerful and elegant way to image complex multiferroic textures and to disentangle the different contributions at play and in particular to image the silent AF order. In this presentation, after discussing the SHG imaging of AF domains distributions in BiFeO3 epitaxial thin films, their ultrafast dynamics will be addressed.

As a wide band gap semiconductor, ZnO have attracted much attention due to the opportunity of combining band gap engineering, with large excitonic binding energies in the UV-visible range. While many wonderful fundamental results (LED, polariton lasers, etc) have been obtained with this material platform thanks a huge improvement of the growth methods, the development has always been limited in terms of applications by a lack of reliable p-type doping.

In this presentation I will address new opportunities of this material platform in a radically different range which does not require p-type doping: from IR to THz.

In the infrared range, Quantum Cascade Lasers are very efficient and already commercialized. Now lots of effort are made to shift to THz due to the numerous potential applications linked to this wavelength domain. But the operation temperature is still limited in the THz range due to an intrinsic limitation of the material systems used (III-V compounds). In this presentation we will show that wurtzite oxides could be good candidates for this application.

After a deep optimization of the designs and the growth processes (1), quantum cascade detectors and emitters have been processed and characterized in the Mid-IR (2) and the THz range (3) demonstrating the huge potential of oxides to address the issue of efficient emitters in the THz range at room temperature. In addition, I will also present new opportunities of these heterostructures in more fundamental fields such as hyperbolic metamaterials (4) and multisubband plasmons (5).

1 N. Le Biavan, et al., Applied Physics Letters 111 (2017).
2 A. Jollivet, et al., Applied Physics Letters 113 (2018).
3 B. Meng, et al., ACS Photonics 8, 343 (2021).
4 A. Hierro, et al., Physical Review Letters 123, 117401 (2019).
5 M. M. Bajo, et al., Physical Review Applied 10 (2018).