Micromanipulation de particules polarisables par diélectrophorèse

International audienceDielectrophoresis can be described as the translational motion of neutral particles caused by polarization effects in a non-uniform electric field. It finds a wide range of applications, such as separation and isolation of particles, cell handling prior to electrofusion, or cell characterization. This paper describes the design and fabrication steps of microdevices devoted to cell manipulation by electric field. The results presented here show latex beads or cells undergoing either positive or negative dielectrophoretic force. We also illustrate how dielectrophoresis can be used to separate particles on the basis of differential polarisability. These results are compared with electric field simulations undertaken using a 3D finite element modelling

Using injection molding for fabrication of a continuous-flow magnetic cell sorter

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Magnetic in situ hybridization (MISH) combined to specifically adapted microfluidics as a complementary approach to metagenomics

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Magnetic in-situ hybridization: a complementary approach for investigating microbial diversity

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A simple method for fabricating new dielectrophoretic microdevices using soft lithography

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Tunable and Label-Free Bacteria Alignment Using Standing Surface Acoustic Waves

International audienceThis paper describes a new technique for focusing bacteria in a microfluidic channel and subsequently controlling their trajectory. Bacteria alignment is obtained using standing surface acoustic waves (SSAW) generated by two interdigitated transducer electrodes (IDTs) patterned on a piezoelectric wafer. The bacteria are focused in the standing wave pressure nodes, separated by half a wavelength, the electrode geometry and applied voltage frequency being chosen accordingly. Interestingly, the position of a pressure node can be modulated by introducing a phase shift between the electrical signals applied to both IDTs. The bacteria, trapped in this node, follow it and can therefore be deflected. This technique works with label-free bacteria in their culture medium and induces low power consumption, which is very interesting for portable devices

A new platform for culture and electroporation of 3d cell constructs based on a porous scaffold

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Bioelectronic chip for negative dielectrophoresis assembly of living cells in ordered network

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A new magnetic cell fishing approach based on hybridization chain reaction: HCR-MISH

International audienceThis paper aims at presenting a new magnetic labelling approach based on in-situ hybridization for the specific capture of bacterial cells. This approach is inspired by HCR-FISH, which was recently proposed as a new sensitive method for the detection of environmental microorganisms using a combination of FISH (Fluorescent In Situ Hybridization) and HCR (Hybridization Chain Reaction). Here we propose to adapt the technique to allow grafting of superparamagnetic nanoparticles onto target bacteria and therefore to exploit magnetism instead of fluorescence for their subsequent isolation using a micro-magnet array. The feasibility of the approach was first assessed by isolating E. coli cells using a universal bacterial probe, Eub338. Then, specific targeting of Escherichia coli DH5a, Pseudomonas putida, and Acinetobacter sp. ADP1 were demonstrated using heterologous probes. For the purpose of comparison, both HCR-FISH and HCR-MISH experimental results are presented