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

Integrative technology-based approach of MEMS for biological applications

International audienc

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

Integrative Technology-Based Approach of Microelectromechanical Systems (MEMS) for Biosensing Applications

International audienc

Individual blood-cell capture and 2D organization on microarrays.: Individual Blood Cell Capture and 2D-Organization on Microarrays

International audienc

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

Interaction of biomolecules sequentially deposited at the same location using a microcantilever-based spotter

International audienceA microspotting tool, consisting of an array of micromachined silicon cantilevers with integrated microfluidic channels is introduced. This spotter, called Bioplume, is able to address on active surfaces and in a time-contact controlled manner picoliter of liquid solutions, leading to arrays of 5 to 20-μm diameter spots. In this paper, this device is used for the successive addressing of liquid solutions at the same location. Prior to exploit this principle in a biological context, it is demonstrated that: (1) a simple wash in water of the microcantilevers is enough to reduce by >96% the cross-contamination between the successive spotted solutions, and (2) the spatial resolution of the Bioplume spotter is high enough to deposit biomolecules at the same location. The methodology is validated through the immobilization of a 35mer oligonucleotide probe on an activated glass slide, showing specific hybridization only with the complementary strand spotted on top of the probe using the same microcantilevers. Similarly, this methodology is also used for the interaction of a protein with its antibody. Finally, a specifically developed external microfluidics cartridge is utilized to allow parallel deposition of three different biomolecules in a single run