Bioplume : a MEMS-based picoliter droplet dispenser with electrospotting means for patterning surfaces at the micro- and the nanometer scales

The interest in patterning surfaces with micro- and nanometer resolutions has been growing fast in recent years, illustrating the tremendous potential of patterning techniques for both fundamental investigations and technological applications in photonics, molecular electronics, and biosensors. Among the various patterning methods, liquid dispensing techniques relying on the use of microcantilevers are very promising for several reasons. The first one is that they permit a direct patterning of the surface with different kinds of materials without any need for prefabricated patterns. Secondly, alignment of the cantilevers with respect to specific regions on the surface is straightforward since the cantilevers themselves can be used as displacement sensors. Moreover, parallel approaches can be developed to meet specific requirements in terms of throughput and fabrication costs. In this thesis we present a liquid spotter (so-called Bioplume) based on the use of silicon microcantilevers. Droplets are formed on the surface by a direct contact method. The fabricated cantilever array is integrated to a closed-loop automated system allowing the control of the droplet homogeneity and the spatial positioning of the microarray. The system relies on the use of force sensors, i.e. piezoresistors, integrated into the cantilevers to adjust the trim and to control the deposition parameters, i.e. contact force and time. By using a specific external loading chip, different liquids can be loaded onto the cantilevers, enabling the parallel deposition of several entities in a single deposition run. Besides, an electrode is incorporated in the channel to allow using electrowetting and electrochemistry. The former is used to actively load the cantilever and to control the drop size during delivery, while the latter is used to drive electrochemical reactions in the deposited picoliter droplets. This tool has been used to print biological solutions, to electrodeposit copper, to electropolym erize functionalized pyrrole and to directly create crystalline microspots of nanobeads. The control of the printed features (resolution, thickness, and composition), the versatility of the printed materials and the added electro-assisted features demonstrate the tremendous potential of the Bioplume tool for research work and industrial applications.