Arrays 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.

We have developed a system for the measurement of the inner profile of high-aspect-ratio microstructures. This system uses silicon micro-probes with a sharp tip at their end and an integrated piezoresistive force sensor. The probes are 1 mm long with a cross-sectional area of 20 × 20 μm2, which allowed characterization of narrow and deep micro-holes having a radius as small as 40 μm. The measurement procedure utilizes an original algorithm, which prevents it from many unwanted phenomena. It is entirely automated by using a computer control.

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