Polyetheretherketone Substrate Research Articles

New type of microfabricated carbon electrodes for high-performance liquid chromatography—Amperometric detection of fat-soluble vitamins and antioxidants

This study evaluates performance of thin-film carbon electrodes prepared by physical vapor deposition of the electrode material on a polyetheretherketone substrate and compares their performance with that of a standard type of glassy carbon electrodes for chromatographic detection cell of thin-layer type. Kaempferol, retinol, retinyl acetate, cholecalciferol, α-tocopherol and γ-tocopherol were selected for the study and their respective detection limits were found to be 0.63, 5.84, 5.91, 28.19, 16.80 and 16.11 pg. The calibration plots were linear for at least three orders of magnitude for all of the six analytes selected for evaluation. Hydrodynamic voltammograms are shown for both types of electrodes for the range of working electrode potentials between +0.40 and +1.40 V. Also shown and discussed are plots of signal-to-noise vs. detection potential. The working electrode potential of +1.30 V was found to be required for an improved long-term stability of detection performance and was suitable for the detection of all six analytes.

Synthesis of Palladium Nanoparticles Using a Continuous Flow Polymeric Micro Reactor

A continuous flow polymeric micro reactor, fabricated using a negative photo resist SU-8 on a 10 x 10 cm PEEK (polyetheretherketone) substrate by standard UV lithography, was utilized to synthesize palladium nanoparticles. The nanoparticles were characterized by Transmission Electron Microscopy, Selected Area Electron Diffraction and X-ray Diffraction. The Pd nanoparticles synthesized in the micro reactor were found to have a narrower size distribution when compared with those obtained by the conventional batch process.

Fabrication of an SU-8 based microfluidic reactor on a PEEK substrate sealed by a ‘flexible semi-solid transfer’(FST) process

A continuous flow polymeric microfluidic reactor utilizing SU-8 as a photoresist on a PEEK (polyetheretherketone) substrate was fabricated by standard UV lithography. Embedded multilayer structures were fabricated between the substrate and the inlets and outlet of the microfluidic reactor that facilitated fabrication of the entire microfluidics using SU-8, resulting in improved bonding between the substrate and the pattern. A ‘flexible semi-solid transfer’ (FST) process, based on a reduced exposure dosage, was developed to seal the microfluidic channels. Scanning electron microscopy (SEM) images and photographs revealed no trace of blockages in channels due to the sealing process. The maximum pressure drop without any leakage was found to be 2.1 MPa. The microfluidic reactor withstood temperatures as high as 150 °C and was found to be suitable for carrying out wet chemical synthesis.

Helium permeation througha-C:H films deposited on polymeric substrates

The influence of amorphous hydrogenated carbon a-C:H coatings on gas permeation through polymer films was investigated. Hydrogenated amorphous carbon (a-C:H) films were deposited, at room temperature, from a CH4/Ar plasma produced by a radio frequency glow discharge system at 13.56 MHz. Polyether–etherketone (PEEK) and polyetherimide foils with different thicknesses were used as substrates. The permeation of He was measured and the reduction of the permeability coefficient is correlated here to the composition and density of the a-C:H films. The density and film structure of the layers were analyzed using x-ray reflectivity and Raman spectroscopy of films deposited onto silicon reference samples. A less pronounced reduction of the permeability coefficients for hard, dense diamond-like layers is reported with respect to those obtained for soft, polymer-like layers on PEEK substrates. Surprisingly, the barrier efficacy of the coating decreases with an increase in a-C:H film density. This unexpected result is attributed to intrinsic stress and the corresponding formation of microcracks. The effect of nitrogen incorporation, which reduces film permeability, is investigated in terms of the stress relaxation mechanism promoted.