We report on a new approach toward a laser-assisted modification of biocompatible polydimethylsiloxane (PDMS) elastomers relevant to the fabrication of stretchable multielectrode arrays (MEAs) devices for neural interfacing technologies. These applications require high-density electrode packaging to provide a high-resolution integrating system for neural stimulation and/or recording. Medical grade PDMS elastomers are highly flexible with low Young’s modulus < 1 MPa, which are similar to soft tissue (nerve, brain, muscles) among the other known biopolymers, and can easily adjust to the soft tissue curvatures. This property ensures tight contact between the electrodes and tissue and promotes intensive development of PDMS-based MEAs interfacing devices in the basic neuroscience, neural prosthetics, and hybrid bionic systems, connecting the human nervous system with electronic or robotic prostheses for restoring and treating neurological diseases. By using the UV harmonics 266 and 355 nm of Nd:YAG laser medical grade PDMS elastomer is modified by ns-laser ablation in water. A new approach of processing is proposed to (i) activate the surface and to obtain tracks with (ii) symmetric U-shaped profiles and (iii) homogeneous microstructure This technology provides miniaturization of the device and successful functionalization by electroless metallization of the tracks with platinum (Pt) without preliminary sensitization by tin (Sn) and chemical activation by palladium (Pd). As a result, platinum black layers with a cauliflower-like structure with low values of sheet resistance between 1 and 8 Ω/sq are obtained.

The present study investigates the possibility of obtaining graphene-like phases (defected graphene, graphene oxide, and reduced graphene oxide) as fine suspensions by applying a novel pulsed laser ablation (PLA) approach in flow mode. Two types of suspensions of microcrystalline graphite in aqueous suspensions and two types of microcrystalline graphite in suspensions of 6% hydrogen peroxide solution were irradiated in a quartz tube through which they flow. The third (λ = 355 nm) and fourth harmonics (λ = 266 nm) of an Nd:YAG laser system (15 ns pulse duration and 10 Hz pulse repetition rate) were used. The morphology of the obtained particles was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by X-ray photoelectron spectroscopy, X-ray diffractometry, and Raman spectroscopy.

The purpose of this work is to demonstrate that laser-induced conductive tracts in AlN ceramic can be applied for fabrication of an integrated resistive heating element. Nanosecond laser processing at a wavelength of 1064 nm of ceramic in vacuum is used for a formation of conductive areas. It is demonstrated that the applied laser fluence and the number of pulses influence strongly the electrical properties of the material in the irradiated zone. The resistance value of the produced tracks with a length of about 4 mm and width of about 1 mm may vary from 17 to about 2000 Ohms, depending on the processing conditions. The material in the processed zone is characterized by means of surface composition, morphology, and electric properties. It is found that the electrical conductivity of the formed structure is based on the ceramic decomposition and formation of aluminum layer. The analysis of the influence of the temperature on the electrical resistance value shows that the material’s conductivity could be preserved after annealing, as in the present study it is confirmed up to 300 °C. The ability of the formed tracks to serve as a basis element of ceramic integrated resistive heater is studied by applying DC voltage. It is found that the fabricated element can be used with a high reliability to about 90 °C without special requirements for contact design and encapsulation. Operation at higher temperatures is also demonstrated as the maximal one achieved is about 150 °C at 10V. The performance of the heater is investigated and discussed as the operation range is defined. The proposed element can be a basis for a design of an integrated heater in ceramic with high stability and applications in everyday life and research.

In this work, investigation is presented of nanostructures based on WO ₃ and SnO ₂ metal oxides produced by nanosecond pulsed laser deposition (PLD) carried out at atmospheric pressure in open air at wavelength of 1064 nm. We focused our attention on the changes in the structure, composition, morphology, electrical and gas sensing properties of WO ₃ samples when a small amount (5wt% or 10wt%) of SnO ₂ is added into the target used for ablation. High porous nanostructures organized in aggregated nanoparticles are observed to form hierarchal-like structure with high surface-to-volume ratio. The electrical characteristics are studied before and after annealing of the samples at 300° C for 10 minutes. I-V curves are measured in two working modes – dark current, and during illumination with UV diode light – photocurrent, before and after annealing. Gas sensitivity of the nanostructures is tested at room temperature under following exposure of NH ₃ , CO, ethanol and acetone at fixed concentration of 30 ppm. The aim is to demonstrate by utilizing facilities of the nanosecond pulsed laser ablation in air, functional nanostructures based on WO ₃ and SnO ₂ metal oxides can be produced and realized as gas sensor elements.

Pulsed laser ablation in liquids is utilized for preparation of composite nanostructures on the basis of Ti_xO_2x-1 and Ag. Plates of bulk Ti and Ag immersed in the corresponding liquid serve as targets in the ablation procedure. A nanosecond Nd:YAG pulsed laser is employed as a source of irradiation. Its fundamental wavelength and the third and fourths harmonic are used both to fabricate and to change the chemical composition and the morphology of the nanostructures considered. The procedure for synthesis of complex nanostructures is performed following a specific sequence, namely, the consecutive laser ablation of the selected targets is followed by a post-ablation irradiation of the colloid obtained of the complex nanostructures. The changes in the characteristics of the complex nanostructures are indirectly evaluated based on the profile of the optical transmission spectra of the as-obtained colloids. The colloids’ properties are controlled by varying the laser beam parameters. Transmission electron microscopy (TEM) is applied for direct visualization of their shape. The chemical composition and the morphology were assessed by high-resolution TEM and SAED analyses.

In this work, we report the fabrication of SnO₂-based composite nanostructures in view of their application as a sensor element toward N₂O gas exposure. The samples were produced by laser ablation of a composite SnO₂-TiO₂ target performed in air at atmospheric pressure (in open air). We examined how the structure, morphology, composition, and physical properties of the samples change with the TiO₂ content being introduced into the SnO₂ target. The laser ablation of SnO₂-based targets in open air produced samples with a structure in which SnO₂ and SnO crystal phases co-existed, as the crystal phases were distinguished in separate nanoparticles. The nanoparticles formed a complex porous structure with oxygen-related defects. We investigated the gas-sensing properties of composite SnO₂-based sensor elements working under UV irradiation. The highest response to N₂O exposure and the fastest response/recovery times were demonstrated by the sensor element produced by the laser ablation of a composite target prepared by 10 wt% TiO₂ in SnO₂. Additionally, we found that a small amount (below 0.1 wt%) of noble metal (Pt) added to the sensor element substantially improved the gas sensor performance without inducing significant structural and/or morphological changes. Further, we explored how simultaneous irradiation of the sensor surface with UV and visible light changes the sensor properties. The best sensor performance toward N₂O exposure was achieved by irradiating the Pt-doped SnO₂-TiO₂ sensor surface simultaneously with UV and red lights.