5 research outputs found
Conception et réalisation d'un microsystème robotisé de dépôt de liquide biologiques par microleviers en silicium pour l'élaboration de biopuces
Président de jury:G. Authié, Professeur, LAAS-CNRS, ToulouseRapporteurs:T. Coleman, Directeur de recherche, IBCP-CNRS, LyonD. Collard, Directeur de recherche, IEMN-CNRS, LilleExaminateurs:G. Pietu, Directeur de recherche, INSERM, ParisInvités:L. Bouet, Directeur Général Délégué, INNOPSYSM.C. Potier, Chargé de recherche, ESPCI-CNRS, ParisA. Martinez, Professeur INSA, LAAS-CNRS, ToulouseDirecteur de thèse:G. Garcia, Sous-Directeur LAAS-CNRS, Professeur INSA, ToulouseCo-directeur de thèse:C. Bergaud, Chargé de recherche, LAAS-CNRS, ToulouseBiochips allow to analyze thousands of samples (DNA, proteins) in hours and therefore to know which gene responds to the action of a certain molecule or takes part of a certain disease. Our work is focused on the design and fabrication of a miniaturized and robotized silicon-cantilever-based microsystem for biological sample deposition to elaborate biochips.After an overview of the different methods to fabricate biochips, we describe our goals. The association of a 50 nm precision positionning system and silicon micro-cantilevers was retained. The method is based on direct contact between those cantilevers and the biochip support. The deposition is made through capillary forces. The originality of our work relies on geometric dimensions (spots of a few microns in diameter), the use of minimal amount of biological samples (picoliters), enabling a lot of depositions with a single loading process. Another advantage relies on the mass production process of our cantilevers which makes our system particularly cost effective.Our study focuses on the checking of our approach on different aspects: a biological one showing our capability to realize DNA and proteins chips and deposit various liquids with a single cantilever; a mechanical one demonstrating our system's compatibility with micro- and nano-technologies (use of cantilevers, positioning and size).Then, the loading process of the cantilevers is highlighted: an electrowetting method is firstly used. Then dielectrophoresis which is well known to manipulate liquids is developped through the use of an electric field applied between aluminum passivated electrodes implemented along the cantilevers. Finally piezoresistors located along the cantilevers allow the detection of the contact with the support. Therefore we have an active control of both the loading process and the deposition process in order to waranty uniformity of contact force and contact time.Les biopuces permettent d'analyser en quelques heures des milliers de séquences (ADN ou protéines) et d'identifier quels gènes répondent à l'action d'une molécule ou sont impliqués dans une maladie. Le travail présenté porte sur la conception et la réalisation d'un système miniaturisé et robotisé de dépôt de produits biologiques par micro-leviers en silicium pour la réalisation de biopuces.Après un descriptif détaillé des différentes techniques pour fabriquer des biopuces, nous expliquons notre démarche et nos objectifs. La combinaison d'une plate-forme de positionnement ayant une précision de 50nm et de micro-leviers en silicium est retenue.La méthode de fabrication est basée sur l'utilisation de ces micro-leviers en silicium et la mise en place d'une technique de dépôt par contact direct entre ces outils et le support de la biopuce. Le dépôt s'effectue par capillarité. L'originalité de notre travail repose sur les dimensions géométriques (dépôts de quelques microns en diamètre), sur l'utilisation de volumes très faibles (quelques picolitres) donc la réalisation de nombreux spots avec un seul chargement de levier. Un autre avantage résidedans le fait qu'il est possible de produire ces leviers en masse, à faible coût en utilisant une technique de réalisation très simple.L'étude se poursuit sur la validation de cette approche suivant différents aspects: un aspect biologique démontrant la possibilité de réaliser des puces à ADN et à protéines et de déposer différents produits avec un seul et même levier; un aspect mécanique démontrant la compatibilité de notre approche avec les micro- et nano-technologies (utilisation des micro-leviers, positionnement et taille).Puis, le problème du chargement des microleviers est traité: une technique d'électromouillage est tout d'abord utilisée mais son efficacité reste limitée. Elle évolue vers la diélectrophorèse, technique connue pour permettre de transporter des liquides en modifiant l'équilibre des charges, où l'application du champ électrique se fait par des électrodes en aluminium passivées placées le long des leviers. Enfin, l'intégration de piézorésistances sur les leviers permet de détecter le contact avec le support. Ainsi, après le contrôle actif du chargement, on peut réaliser un contrôle actif du dépôt, en garantissant une uniformité dans la force d'appui et le temps de contact
Cantilever-based microsystem for contact and non-contact deposition of picoliter biological samples
International audienceThis paper describes a cantilever-based microsystem that permits the deposition of picoliter biological samples using a contact or non-contact method. Arrays of silicon-based cantilevers have been used to produce DNA microarrays. An electrowetting-on-dielectric (EWOD) principle is applied for the loading of the liquid by controlling surface tension. Deposition is achieved by direct contact between cantilevers and the surface by capillary transport. A non-contact deposition method has also been developed. It consists in an electric-field applied between the cantilevers and a conductive surface. The results obtained demonstrate that our system meets the need for producing high-density DNA, protein and cell chips
Fabrication of biological microarrays using microcantilevers
International audienceArrays of silicon-based microcantilevers with properly designed passivated aluminum electrodes have been used to generate microarrays by depositing microspots of biological samples using a direct contact deposition technique. The approach proposed here can be compared to the dip-pen technique but with the noticeable difference that electrostatic fields are generated onto the cantilevers to increase the height of liquid rise on the cantilever surface when dipping them into the liquid to be deposited. Both electrowetting through the reduction of the contact angle and dielectrophoresis through electrostatic forces can be used to favor the loading efficiency. These phenomena are particularly pronounced on the microscale due to the fact that physical scaling laws favor electrostatic forces. Moreover, at this scale, conductive heat dissipation is enhanced and therefore joule heating can be minimized. Using this approach, with a single loading, arrays of more than a hundred spots, from the femtoliter to the picoliter range, containing fluorescent-labeled oligonucleotides and proteins were directly patterned on a glass slide
Silicon-based microcantilevers for multiple biological sample deposition
International audienceArrays of silicon-based microcantilevers with passivated aluminum electrodes properly designed have been used to generate microarrays by depositing microspots of biological samples using a direct contact deposition technique. Using this approach, with a single loading, arrays of more than a hundred spots, from the femtoliter to the picoliter range, containing fluorescent-labelled oligonucleotides (15 mers) and proteins were directly patterned on a glass slide. The aim here was to check whether our system could be used for depositing various biological samples with the same cantilevers without the need to replace them for each sample. The strategy was to adapt the conventional cleaning and drying procedures used with a commercial DNA or protein microspotter. All the results presented demonstrate that our system perfectly matches the need for generating high-density DNA and protein chips in terms of size, density and the capacity of depositing different samples without cross-contamination
Nanostructuring Surfaces with Conjugated Silica Colloids Deposited Using Silicon-Based Microcantilevers
In this paper, the assembly and stability of locally spotted spherical nanoparticles onto various substrates are studied. Arrays of silicon-based microcantilevers, combined with an automated three-stage spotter, are used to deposit picolitre droplets containing 300 nm diameter polyethylene glycol and 150 nm diameter amino conjugated silica nanospheres onto silicon, allylamine and acrylic acid surfaces. Matrices of colloid spots ranging from 10 to 100 µm in diameter have been successfully patterned. SEM characterizations of the nanoparticles' geometry and spatial distribution within the spots were carried out, showing the colloid aggregation at the droplet's rim and the selective stability of the printed patterns. The expected substrate functionalization was assessed by XPS characterizations of the nanoparticles' surfaces. Finally, polyethylene glycol–SiO2 nanoparticle conjugates were used as masks during a selective reactive ion etching of the silicon substrate, and silicon nanopillars have been obtained. This work opens up possibilities of high spatial resolution nanopatterning with nanoparticle conjugates.JRC.I.4-Nanotechnology and Molecular Imagin