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Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial as encapsulation and/or as substrate insulator carrier for long term neural implants because of its remarkable properties. Femtosecond (λ = 263 and 527 nm) and nanosecond (266 and 532 nm) laser processing of PDMS-elastomer surface, in air, is investigated. The influence of different processing parameters, including laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses, on the surface activation and the surface morphology are studied. High definition tracks and electrodes are produced. Remarkable alterations of the chemical composition and structural morphology of the ablated traces are observed in comparison with the native material. Raman spectra illustrate well-defined dependence of the chemical composition on the laser fluence, pulse duration, number of pulses and wavelength. An extra peak about ∼512–518 cm−1, assigned to crystalline silicon, is observed after ns- or visible fs-laser processing of the surface. In all cases, the intensities of Sisingle bondOsingle bondSi symmetric stretching at 488 cm−1, Sisingle bondCH3 symmetric rocking at 685 cm−1, Sisingle bondC symmetric stretching at 709 cm−1, CH3 asymmetric rocking + Sisingle bondC asymmetric stretching at 787 cm−1, and CH3 symmetric rocking at 859 cm−1, modes strongly decrease. The laser processed areas are also analyzed by SEM and optical microscopy. Selective Pt or Ni metallization of the laser processed traces is produced successfully via electroless plating. The metallization process is not sensitive with respect to the time interval after the laser treatment. DC resistance is measured to be as low as 0.5 Ω mm−1. Our results show promising prospects with respect to use such a laser-based method for micro- or nano-fabrication of PDMS devices for MEMS and NEMS.

Thin Er, Yb co-doped Y2O3 films were grown by pulsed laser deposition from ceramic target. Subsequent ion implantation with 1.1 MeV Er+ ions to a fluence of 6 × 1014 at/cm2 at room temperature was performed in order to modify the structure of the as-deposited films. The as-deposited films have a polycrystalline column-like structure. Ion implantation induces defects into the as-deposited films. After annealing at 900 °C for 1 h in oxygen atmosphere, the films recrystallize in roundly shaped grain-like structure with grain size of about 100 nm. The Er3+ photoluminescence response was obtained for all the films by excitation through cross-relaxation of Yb3+ ions. The IR emission spectrum, consisting of two narrow peaks at 1415 and 1514 nm, differs from the typical spectra of Er-doped materials. The VIS emission spectrum observed in as-deposited films does not appear after implantation and subsequent 900 °C annealing. © 2007 Elsevier B.V. All rights reserved., This work was supported in part by EU project NANOPHOS, Contract IST-2001-39112 and by the Bulgarian Ministry of Education and Science under Contract MUF-1511.

Optically active Er3+:Yb3+ codoped Y 2O3 films have been produced on c-cut sapphire substrates by pulsed laser deposition from ceramic Er:Yb:Y2O3 targets having different rare-earth concentrations. Stoichiometic films with very high rare-earth concentrations (up to 5.5 × 1021 at cm - 3) have been achieved by using a low oxygen pressure (1 Pa) during deposition whereas higher pressures lead to films having excess of oxygen. The crystalline structure of such stoichiometric films was found to worsen the thicker the films are. Their luminescence at 1.53 μm and up-conversion effects have been studied by pumping the Yb3+ at 0.974 μm. The highest lifetime value (up to 4.6 ms) is achieved in films having Er concentrations of ≈ 3.5 × 1020 at cm- 3 and total rare-earth concentration ≈ 1.8 × 1021 at cm- 3. All the stoichiometric films irrespective of their rare-earth concentration or crystalline quality have shown no significant up-conversion. © 2005 Elsevier B.V. All rights reserved., This work has been partially supported by the EU project NANOPHOS (Contract IST-2001-39112), by the Bulgarian National Science Foundation (Contract MUF-02/05), by the Spanish Ministry of Education and Science (Project MAT2000-1135-C02-02) and by the CSIC-Bulgarian Academy of Sciences bilateral cooperation program.