Laser induced forward transfer of SnO2 for sensing applications using different precursors systems

This paper presents the transfer of SnO₂ by laser induced forward transfer (LIFT) for gas sensor applications. Different donor substrates of SnO₂ with and without triazene polymer (TP) as a dynamic release layer were prepared. Transferring these films under different conditions were evaluated by optical microscopy and functionality. Transfers of sputtered SnO₂ films do not lead to satisfactory results and transfers of SnO₂ nanoparticles are difficult. Transfers of SnO₂ nanoparticles can only be achieved when applying a second laser pulse to the already transferred material, which improves the adhesion resulting in a complete pixel. A new approach of decomposing the transfer material during LIFT transfer was developed. Donor films based on UV absorbing metal complex precursors namely, SnCl₂(acac)₂ were prepared and transferred using the LIFT technique. Transfer conditions were optimized for the different systems, which were deposited onto sensor-like microstructures. The conductivity of the transferred material at temperatures of about 400 ^°C are in a range usable for SnO₂ gas sensors. First sensing tests were carried out and the transferred material proved to change conductivity when exposed to ethanol, acetone, and methane.     

Role of thermal stresses on pulsed laser irradiation of thin films under conditions of microbump formation and nonvaporization forward transfer

This paper presents a theoretical analysis of the processes in thin solid films irradiated by short and ultrashort laser pulses in the regimes of film structuring and laser-induced forward transfer. The regimes are considered at which vaporization of the film materials is insignificant and film dynamics is governed mainly by mechanical processes. Thermoelastoplastic modeling has been performed for a model film in one- and two-dimensional geometries. A method has been proposed to estimate the height of microbumps produced by nanosecond laser irradiation of solid films. Contrary to femtosecond laser pulses, in nanosecond pulse regimes, stress waves across the film are weak and cannot induce film damage. The main role in laser-induced dynamics of irradiated films is played by radial thermal stresses which lead to the formation of a bending wave propagating along the film and drawing the film matter to the center of the irradiation spot. The bending wave dynamics depends on the hardness of the substrate underlying the film. The causes of the receiver substrate damage sometimes observed upon laser-induced forward transfer in the scheme of the direct contact between the film and the receiver are discussed.     

An ultra-sensitive online SPE-LC-MS/MS method for the quantification of levonorgestrel released from intrauterine devices

A selective and sensitive liquid chromatography-tandem mass spectrometry method for the determination of very low levonorgestrel (d-(−)-norgestrel) serum levels such as those found in patients using levonorgestrel-releasing intrauterine devices (IUDs) was developed. To achieve the sub-nanomolar sensitivity needed to measure such serum levels, a diethyl ether extraction sample preparation protocol was applied prior to the online solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) assay. Analyte quantification from the selected reaction monitoring experiments relied on the use of sixfold deuterated norgestrel as internal standard. The final method was linear up to 1.50 ng/ml with a lower limit of quantification (LLOQ) of 0.05 ng/ml. It was found to be precise and accurate with imprecision <8% and bias <6% assessed at three control levels. Total analyte recovery measured in patient pools at three concentration levels was found to exceed 92%. Matrix interferences were excluded by post-column analyte infusion experiments. As a proof of concept, a set of IUD patient serum samples was screened for their levonorgestrel content. A total of 97.5% (n = 94) of the samples did show serum levels exceeding the LLOQ, proving the applicability of the assay in relevant clinical cohorts. This method must not be used for diagnostic or therapeutic purposes, since it did not undergo formal performance evaluation in the sense of the in vitro diagnostic directive (98/79/EG) of the European community.     

Near-Infrared Diffuse Reflection Spectroscopy and Multivariate Calibration Hyphenated with Thin-Layer Chromatography for Quality Control of a Phytomedicine and Simultaneous Quantification of Methoxylated Flavones

JPC – Journal of Planar Chromatography – Modern TLC - By use of near infrared (NIR) spectroscopy hyphenated to thinlayer chromatography (TLC) for analysis of methoxylated flavones in a...     

Experimental quantum teleportation of arbitrary quantum states

Received: 1 July 1998/Revised version: 2 October 1998