Arrays of high aspect ratio magnetic microstructures for large trapping throughput in lab-on-chip systems

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Influence du diélectrique de grille et de la structure moléculaire du semi conducteur sur les performances de transistors organiques

Ce travail porte sur l'étude de l'influence du diélectrique de grille et de la structure moléculaire du semi conducteur sur les performances de transistors organiques (OFET). L'obtention d'OFET stables, fonctionnant à de faibles tensions tout en présentant de bonnes performances constitue un aspect déterminant de ces dispositifs. Dans ce contexte, nous avons réalisé des transistors en pentacène, avec différents diélectriques de grille. Nous proposons un diélectrique bicouche, composé d'un isolant à forte constante et d'un isolant polymère, qui permet, en associant les avantages de ces deux matériaux d'obtenir des tensions de fonctionnement de 15V, tout en améliorant les mobilités des porteurs de charges et en minimisant les instabilités électriques générées par le diélectrique à forte constante. Nous avons ensuite réalisé des transistors, à partir de dérivés d'oligothiophènes et étudié l'impact de la structure moléculaire sur les dispositifs.This work reports on an investigation of the influence of the gate dielectric and the molecular structure of the semiconductor on organic field effect transistors (OFETs) performances. The challenge has been to obtain low voltage, high mobility and stable OFET. Within this context, pentacene based transistors with different gate dielectric materials were realized. We propose a bilayer dielectric, composed by an high-k insulator and a polymeric insulator. This combination give devices working at rather low voltage (15V), while the field effect mobility is improved and the electrical instabilities generated by the high-k dielectric are minimized. In a second part, we have realized transistors, with different oligothiophenes derivatives as active layer and studied the impact of the molecular structure on devices. The addition of hexyls chains and benzothiophene and naphthothiophene groups improves the charge transport. The respective influence of these incorporations are investigated.LYON-Ecole Centrale (690812301) / SudocSudocFranceF

Microfluidic-Based Technologies for CTC Isolation: A Review of 10 Years of Intense Efforts towards Liquid Biopsy

The selection of circulating tumor cells (CTCs) directly from blood as a real-time liquid biopsy has received increasing attention over the past ten years, and further analysis of these cells may greatly aid in both research and clinical applications. CTC analysis could advance understandings of metastatic cascade, tumor evolution, and patient heterogeneity, as well as drug resistance. Until now, the rarity and heterogeneity of CTCs have been technical challenges to their wider use in clinical studies, but microfluidic-based isolation technologies have emerged as promising tools to address these limitations. This review provides a detailed overview of latest and leading microfluidic devices implemented for CTC isolation. In particular, this study details must-have device performances and highlights the tradeoff between recovery and purity. Finally, the review gives a report of CTC potential clinical applications that can be conducted after CTC isolation. Widespread microfluidic devices, which aim to support liquid-biopsy-based applications, will represent a paradigm shift for cancer clinical care in the near future

Magnetic polymers for magnetophoretic separation in microfluidic devices

International audienceMagnetophoresis offers many advantages for manipulating magnetic targets in microsystems. The integration of micro-flux concentrators and micro-magnets allows achieving large field gradients and therefore large reachable magnetic forces. However, the associated fabrication techniques are often complex and costly, and besides, they put specific constraints on the geometries. Magnetic composite polymers provide a promising alternative in terms of simplicity and fabrication costs, and they open new perspectives for the microstructuring, design, and integration of magnetic functions. In this review, we propose a state of the art of research works implementing magnetic polymers to trap or sort magnetic micro-beads or magnetically labeled cells in microfluidic devices

Biosensors for circulating tumor cells (CTCs)-biomarker detection in lung and prostate cancer: Trends and prospects

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Magnetic filaments for anisotropic composite polymers

International audienceThe use of contactless magnetic forces meets numerous needs in microelectromechanical systems (MEMS) or microfluidic devices. In this view, heterogeneous materials integrating magnetic nanostructures within a non-magnetic matrix such as polymer can produce local variations of magnetic field, at the sub-micrometer scale. Here we report on the synthesis of magnetic composites using electrospun nanofilaments and a polydimethylsiloxane (PDMS) matrix. Varying the precursor nature and heat treatment conditions, we obtained single phase filaments of Fe, FeNi, and MFe2O4 (M = Co, Fe, Ni). Thanks to a fine investigation of their structure and morphology, it was possible to measure from magnetically-soft (µ0HC ≤ 5 mT) to relatively hard (µ0HC up to 93 mT, MR/MS up to 0.5) behaviors. The common one-dimensional shape of these filaments leads to an anisotropic magnetic response. This can be exploited to achieve self-organization of the filaments in arrays within the non-magnetic matrix. We show the first step towards the development of magnetically anisotropic membranes of PDMS with 0.23 wt% Fe filaments. These composite materials are promising for implementing magnetic functions in microsystems while circumventing complex micro-fabrication steps

Magnetophoretic manipulation in microsystem using carbonyl iron-polydimethylsiloxane microstructures

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A New Microfluidic Device for Electric Lysis and Separation of Cells

International audienceThis paper demonstrates the potential use of a new microfluidic device embedding thick electrodes for cell lysis and cell separation applications. The system consists of a microfluidic channel featuring conductive walls made of a polydimethylsiloxane (PDMS) matrix mixed with carbon nanoparticles. Cell lysis was performed electrically by applying square pulses across the channel width, which was monitored by fluorimetry. Lysed and unlysed cells showed different dielectrophoretic behavior under appropriate experimental conditions, which suggests that the developed device is suitable to perform both cell lysis and subsequent sorting of viable and dead cells

Xurography-based microfluidic algal biosensor and dedicated portable measurement station for online monitoring of urban polluted samples

International audienceA critical need exists to develop rapid, in situ, and real-time tools to monitor the impact of pollution discharge toxicity on aquatic ecosystems. The present paper deals with the development of a novel, simple-to-use, low-cost, portable, and user-friendly algal biosensor. In this study, a complete and autonomous portable fluorimeter was developed to assess the A-chlorophyll fluorescence of microalgae, inserted by capillarity into low-cost and disposable xurography-based microfluidic chips. Three microalgae populations were used to develop the biosensor: Chlorella vulgaris, Pseudokirchneriella subcapitata, and Chlamydomonas reinhardtii. Biosensor feasibility and sensitivity parameters, such as algal concentration and light intensity, were optimized beforehand to calibrate the biosensor sensitivity with Diuron, a pesticide known to be very toxic for microalgae. Finally, the biosensor was employed in 10 aqueous urban polluted samples (7 urban wet-weather discharges and 3 wastewaters) in order to prove its reliability, reproducibility, and performance in the detection of toxic discharges in the field

Magnetic Membranes for Cell Growth Under Curved and Reversible Deformations

International audienceMagnetic polymer composites are very versatile candidates to fabricate soft robots and actuators thanks to their unique properties such as flexibility and shape memory effect. Thus, the possibility to reproduce natural shapes provides new tools for bioengineering applications. The wide panel of deformations of magnetic polymer composites can be implemented to mimic the movements and curvatures of living tissue. Herein, magnetic polymer membranes are developed to explore cell growth under curved, reversible, and controlled deformations. NdFeB/polydimethylsiloxane composite membranes (86 μm and 46 μm thick) are obtained by soft lithography and magnetized in rolled position under 3 T. Once actuated by a low magnetic field (5–86 mT), the membranes are deformed in wavy shapes with a deformation height of maximum 1.4 and 1.7 mm and a curvature radius of minimum 1.8 and 0.6 mm (86 μm and 46 μm thick membranes, respectively), for a maximum magnetic field of 86 mT. Then, Caco‐2 cell viability is studied on deformed substrates under a static (106 mT) and varying (8–78 mT) magnetic field. No increase in cell death is observed, validating a well‐characterized and promising approach for a new generation of dynamic and curved substrates for cell culture