Polymer-Based Microcantilevers

Injection molding, an economical mass production technique, has also been used to fabricate microcantilevers out of thermoplastic polymers (McFarland et al. 2004 McFarland and Colton 2005a, b). In this process, a molten polymer such as polypropylene is forced under pressure into a steel cavity (mold) the shape of the cavity defines the dimensions of both the base and the cantilever(s). Injection-molded microcantilevers have been shown to be of equal caUber to commercial silicon miCTOcantile-vers. McFarland et al. (2004) and McFarland and Colton (2005a, b) specified in detail the fabrication of injection-molded microcantilevers. Despite their advantages over silicon-based cantilever arrays, polymeric cantilever arrays are not commercially available. 

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The cantilevers can be fabricated of any shape and from substantially any material utilized in microelectronics industry, i.e. crystalline or poly-silicon, silicon nitride, silicon oxide, polymer materials (see Note 2). The rectangular shape beams are the most frequently used in biological research. In biological sensors based on the bending method, it is important to have the cantilevers flat and in plane with the base surface. Initial offset or curvature of the beams complicates adjustment of the experimental setup, especially, if working with arrays of cantilever. For this reason, the most common material for cantilevers fabrication nowadays is single crystalline silicon. A large variety of biomolecular interactions have been detected with silicon microcantilevers. 

Zhang XR, Xu XF (2004) Development of a biosensor based on laser-fabricated polymer microcantilevers. Appl Phys Lett 85 2423-2425... 

Sensors based on gas sorption Polymer sensors (swelling) Fiber-optic sensors Mass sensitive (quartz crystal microbalance (QMB) surface (SAW) and bulk acoustic wave (BAW), microcantilevers)... 

Janata J, Josowicz M (2003) Conducting polymers in electronic chemical sensors. Nat Mater 2 19-24 Jesenius H, Thaysen J, Rasmussen AA, Veje LH, Hansen O, Boisen A (2000) A microcantilever-based alcohol vapor sensor-application and response model. Appl Phys Lett 76 2615-2617 Jiang L, Jun H-K, Hoh Y-S, Lim J-O, Lee D-D, Huh J-S (2005) Sensing characteristics of polypyrrole-poly(vinyl alcohol) methanol sensors prepared by in situ vapor state polymerization. Sens Actuators B 105 132-137 Jin Z, Su YX, Duan YX (2001) Development of a polyanUine-based optical ammonia sensor. Sens Actuators B 72 75-79... 

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