43 research outputs found
The fabrication, characterisation and electrochemical investigation of screen-printed graphene electrodes
We report the fabrication, characterisation (SEM, Raman spectroscopy, XPS and ATR) and electrochemical
implementation of novel screen-printed graphene electrodes. Electrochemical characterisation of the fabricated
graphene electrodes is undertaken using an array of electroactive redox probes and biologically relevant
analytes, namely: potassium ferrocyanide(II), hexaammine-ruthenium(III) chloride, N,N,N0 ,N0-tetramethyl-pphenylenediamine
(TMPD), b-nicotinamide adenine dinucleotide (NADH), L-ascorbic acid (AA), uric acid (UA)
and dopamine hydrochloride (DA). The electroanalytical capabilities of the fabricated electrodes are also
considered towards the sensing of AA and DA. The electrochemical and (electro)analytical performances of
the fabricated screen-printed graphene electrodes are considered with respect to the relative surface
morphologies and material compositions (elucidated via SEM, Raman, XPS and ATR spectroscopy), the density
of electronic states (% global coverage of edge-plane like sites/defects) and the specific fabrication conditions
utilised. Comparisons are made between two screen-printed graphene electrodes and alternative graphite
based screen-printed electrodes. The graphene electrodes are fabricated utilising two different commercially
prepared ‘graphene’ inks, which have long screen ink lifetimes (43 hours), thus this is the first report of a true
mass-reproducible screen-printable graphene ink. Through employment of appropriate controls/comparisons
we are able to report a critical assessment of these screen-printed graphene electrodes. This work is of high
importance and demonstrates a proof-of-concept approach to screen-printed graphene electrodes that are
highly reproducible, paving the way for mass-producible graphene sensing platforms in the future
The fabrication, characterisation and electrochemical investigation of screen-printed graphene electrodes
We report the fabrication, characterisation (SEM, Raman spectroscopy, XPS and ATR) and electrochemical
implementation of novel screen-printed graphene electrodes. Electrochemical characterisation of the fabricated
graphene electrodes is undertaken using an array of electroactive redox probes and biologically relevant
analytes, namely: potassium ferrocyanide(II), hexaammine-ruthenium(III) chloride, N,N,N0 ,N0-tetramethyl-pphenylenediamine
(TMPD), b-nicotinamide adenine dinucleotide (NADH), L-ascorbic acid (AA), uric acid (UA)
and dopamine hydrochloride (DA). The electroanalytical capabilities of the fabricated electrodes are also
considered towards the sensing of AA and DA. The electrochemical and (electro)analytical performances of
the fabricated screen-printed graphene electrodes are considered with respect to the relative surface
morphologies and material compositions (elucidated via SEM, Raman, XPS and ATR spectroscopy), the density
of electronic states (% global coverage of edge-plane like sites/defects) and the specific fabrication conditions
utilised. Comparisons are made between two screen-printed graphene electrodes and alternative graphite
based screen-printed electrodes. The graphene electrodes are fabricated utilising two different commercially
prepared ‘graphene’ inks, which have long screen ink lifetimes (43 hours), thus this is the first report of a true
mass-reproducible screen-printable graphene ink. Through employment of appropriate controls/comparisons
we are able to report a critical assessment of these screen-printed graphene electrodes. This work is of high
importance and demonstrates a proof-of-concept approach to screen-printed graphene electrodes that are
highly reproducible, paving the way for mass-producible graphene sensing platforms in the future
Determination of the bond strength of some microns coatings using the laser shock technique
High power laser shocks with a 0.6Â ns pulse duration have been used to study the debonding
of coatings electrolytically deposited on the opposite face of the substrate than the one
shocked. Experiments have been carried out on various substrate/coating systems such as
stainless steel/copper or nickel and hastelloy X/platinum. Experimentally, a lower intensity
debonding threshold has been determined for each of these systems. On the other hand, an
upper threshold above which a systematic removal of the coating is obtained has been
evidenced. By the numerical simulation of these experiments, a traction range for debonding
at the interface has been determined for the three systems. A significant difference for the
adhesion levels of these systems has been evidenced using this method. Thus, the possibility
to use the laser shock technique as a non destructive adhesion test for coatings of some tens
microns is clearly demonstrated
Growth mechanism investigation of SnO2 thin films deposited by aerosol pyrolysis for biosensor applications: Importance of the thickness
International audienceTransparent conductive oxide films are suitable sensitive layers for gas sensors and biosensors, provided that their intrinsic properties are controlled, notably considering their thickness dependence. The present paper reports on a study of the variation of some physical properties of polycrystalline Sb doped SnO2 films according to the film thickness. Films were deposited onto Si and glass substrates by aerosol pyrolysis. Their thickness was varied in a range of 20-280 nm. The electrical resistivity, the roughness, the optical constant, the microstructure and the texture were investigated. Correlated evolutions of the resistivity and the surface roughness are found in relation with the evolutions of both the microstructure and the texture. Two main successive growth steps were evidenced which are delimited by a critical film thickness. Below this thickness of approximately 100-120 nm, a strong dependence of physical properties with the thickness is evidenced whereas for thicker films no significant change is evidenced. A two-step growth model is proposed to explain this behaviour. This mechanism growth is to be considered in view of the integration of SnO2 films as sensitive layers in biosensors. Notably, in the case of biosensors based on the label-free electrochemical detection of biomolecules, it is recommended to use films with thicknesses ranging above the critical thickness value of 100-120 nm in order to obtain optimized, reproducible and comparable responses of biosensors. (c) 2012 Elsevier B.V. All rights reserved
Continuous assessment of care-related pain in paediatric rehabilitation centres: Methodology, relevance and validity
EFFECT OF GROWTH-HORMONE TREATMENT ON CRANIOFACIAL GROWTH IN TURNERS SYNDROME
A cephalometric study was performed in 19 patients with Turner's syndrome, aged 8.7-16.5 years. A lateral roentgencephalogram was taken before and after two years of treatment with biosynthetic growth hormone in a dose of 24 IU/m2/week. During two years of growth hormone treatment, the mandibular length increased mainly due to vertical growth. The initially posteriorly rotated mandible showed an anterior rotation, although the normal position was not reached. The other linear measurements and angles did not change during treatment. No indications were found for an increase in the disproportionate growth or for excessive chin growth as a sign of acromegaly during growth hormone treatment. In conclusion, growth hormone treatment in patients with Turner's syndrome resulted in an increase in mandibular length, mainly due to vertical growth of the ramus and in the anterior rotation of the mandible
Effect of growth hormone treatment on craniofacial growth in Turner's syndrome
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