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Optical nanotip arrays fabricated on etched fiber bundles were functionalized with DNA spots. Such unconventional substrates (3D and non-planar) are difficult to pattern with standard microfabrication techniques but, using an electrochemical cantilever, up to 400 spots were electrodeposited on the nanostructured optical surface in 5 min. This approach allows each spot to be addressed individually and multiplexed fluorescence detection is demonstrated. Finally, remote fluorescence detection was performed by imaging through the optical fiber bundle itself after hybridisation with the complementary sequence.

A high-density array of opto-electrochemical nanosensors is presented for remote DNA detection. It was fabricated by chemical etching of a coherent optical fibre bundle to produce a nanotip array. The surface of the etched bundle was sputter-coated with a thin ITO layer which was eventually insulated by an electrophoretic paint. The fabrication steps produced a high-density array of electrochemical nanosensors which retains the optical fibre bundle architecture and its imaging properties. A DNA probe was then immobilized on the nanosensor array surface in a polypyrrole film by electropolymerisation. After hybridisation with the complementary sequence, detection of the strepavidin-R-phycoerythrin label is performed by fluorescence imaging through the optical fibre bundle itself. Control experiments and regeneration steps have also been successfully demonstrated on this nanostructured opto-electrochemical platform.

A patterning tool that allows electrochemical reactions to take place inside microdroplets is introduced. This tool relies on the use of a microfabricated array of silicon cantilevers that incorporate a channel into which a gold electrode is patterned. The deposition process consists in forming picoliter droplets onto a conducting surface by a contact method and applying a voltage between the surface and the cantilevers. To demonstrate the capability of the system, arrays of 20 μm diameter copper islands are electrodeposited onto gold surfaces. As expected, the copper bumps exhibit increasing heights as a result of longer deposition times. [ABSTRACT FROM AUTHOR]