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Ribeiro, Celso, Pedro Brogueira, Guilherme Lavareda, Carlos Nunes de Carvalho, Ana Amaral, Luis Santos, Jorge Morgado, Ulrich Scherf, and Vasco D. B. Bonifacio. "Ultrasensitive microchip sensor based on boron-containing polyfluorene nanofilms." BIOSENSORS & BIOELECTRONICS 26 (2010): 1662-1665. Abstract

A fluorene-based pi-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. (C) 2010 Elsevier B.V. All rights reserved.

Parreira, P., G. Lavareda, J. Valente, F. T. Nunes, A. Amaral, and C. Nunes de Carvalho. "Undoped InOx Films Deposited by Radio Frequency Plasma Enhanced Reactive Thermal Evaporation at Room Temperature: Importance of Substrate." JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 10 (2010): 2701-2704. Abstract

Conductive and transparent undoped thin films of indium oxide (InOx), 120 nm average thick, were deposited by radio frequency plasma enhanced reactive thermal evaporation (rf-PERTE) of indium in the presence of oxygen at room temperature. Several substrates were used in order to study their influence on the main properties of these films: alkali free (AF) glass, fused silica, crystalline silicon and polyethylene terephthalate (PET). Surface morphology of the InOx films as a function of the substrates was observed by SEM and showed that the undoped InOx films obtained are nano-structured. For the c-Si substrate, InOx films with increased grain size are obtained, induced by the crystalline substrate. Films deposited on fused silica and AF glass substrates show a nano-grainy surface with similar surface morphologies. The InOx films deposited on AF glass show the highest values of both: electrical conductivity of about 1100 (Omega cm)(-1) and visible transmittance of 85%. The substrate has a greater influence on the surface morphology of the films when a polymer (PET) is used. InOx films deposited on PET show a decrease in the electrical conductivity (90 (Omega cm)(-1)) and a slight decrease in the average visible transmittance (78%).