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Microstríps, iranamisaion lines of metallic layers deposited on a di

Microscopic lenses, fabricated on optical fiber surfaces, have quadrupled the efficiency for coupling astigmatic beams from GaAs junction lasers into 4-microm cores of single-mode fibers. A novel photolithographic technique was used to make hemispherical and hemicylindrical microlenses, with diameters between 4 microm and 10 microm, from commercially available negative type photoresist that is transparent at ir laser wavelengths. Geometrical profiles of photoresist lenses, documented with scanning electron photomicrographs, were remarkably smooth even though their dimensions were more than an order of magnitude smaller than other known lenses.

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We report on the fabrication of a boron-doped nanocrystalline diamond (NCD) 3 × 3 high-density microelectrode array (MEA) for amperometric measurements, with a single electrode area of 3 × 5 μm 2 and a separation in the μm scale. The NCD microelectrodes were grown by hot filament chemical vapor deposition (HFCVD) on a double-side polished sapphire wafer in order to preserve the diamond transparency. Bias enhanced nucleation (BEN) was performed to ensure a covalent adhesion of the films to the substrate. A current background noise of less than 5 pA peak to peak over a 1 kHz bandwidth resulted from an electrochemical investigation of the new device, using 100 mM KCl solutions and ferrocyanide red-ox couples. Cyclic voltammetry measurements in physiological buffer solution and in the presence of oxidizable biomolecules strengthened its suitability for bio-sensing. When compared to a 2 × 2 NCD microelectrode array prototype, already used for in vitro cell measurements, the signal to noise ratio of the amperometric response of the new 3 × 3 device proved twice as good. In addition, the optical transmittance of the boron-doped thin layers exceeded 40% in the visible wavelength range. The excellent electrochemical properties of NCD electrodes and the transparency in combination with the high spatial resolution make the new 3 × 3 NCD MEA a promising tool for electrochemical sensing in a variety of applications, ranging from medical to industrial, in neutral or harsh environments.