A growing interest in diamond materials has been shown in the recent year for the design of smart chemical and biochemical sensors due to the remarkable physical and chemical properties of diamond. ...In this paper, modified diamond nanoparticles (DNPs) coatings are investigated as sensitive layers on surface acoustic wave sensor (SAW sensor) for the detection of volatile chemicals. DNPs are deposited onto SAW transducers by a layer-by-layer deposition method and then surface treated to fix them on the substrate and to enhance their affinity to specific compounds such as nitro-aromatic compounds, nerve-agent stimulants, or toxic gases. Homogeneous and reproducible coatings were achieved. The diamond coatings’ surface was either oxidised or reduced to see the effect on the response to ammonia gas, ethanol, DNT or DMMP vapours exposures. The sensors were generally very sensitive to the target chemicals and the response fully reversible. Oxidation of the surface promoted hydrogen-bond formation and therefore enhanced the response to most vapours under test. Even though the sensors were not very selective, we demonstrated the suitability of DNP coatings as stable and reliable sensing interface. This opens up wide opportunities for immobilizing more selective and highly sensitive chemical/biochemical receptors onto SAW transducer surfaces via strong covalent binding of those receptors on diamond nanoparticles deposited homogeneously on the SAW sensors surfaces.
Odorant binding proteins (OBPs) are small soluble proteins found in olfactory systems that are capable of binding several types of odorant molecules. Cantilevers based on polycrystalline diamond ...surfaces are very promising as chemical transducers. Here two methods were investigated for chemically grafting porcine OBPs on polycrystalline diamond surfaces for biosensor development. The first approach resulted in random orientation of the immobilized proteins over the surface. The second approach based on complexing a histidine-tag located on the protein with nickel allowed control of the proteins׳ orientation. Evidence confirming protein grafting was obtained using electrochemical impedance spectroscopy, fluorescence imaging and X-ray photoelectron spectroscopy. The chemical sensing performances of these OBP modified transducers were assessed. The second grafting method led to typically 20% more sensitive sensors, as a result of better access of ligands to the proteins active sites and also perhaps a better yield of protein immobilization. This new grafting method appears to be highly promising for further investigation of the ligand binding properties of OBPs in general and for the development of arrays of non-specific biosensors for artificial olfaction applications.
•We grafted porcine odorant binding protein (OBP) onto diamond surfaces.•Orientation of immobilized OBP could be controlled.•The process has been applied successfully to bio-MEMS sensors.•OBP grafted diamond cantilevers detect odorant molecules such as 2,4-dinitrotoluene.
Boron doped nanocrystalline diamond is known as a remarkable material for the fabrication of sensors, taking advantage of its biocompatibility, electrochemical properties, and stability. Sensors can ...be fabricated to directly probe physiological species from biofluids (e.g. blood or urine), as will be presented. In collaboration with electrophysiologists and biologists, the technology was adapted to enable structured diamond devices such as microelectrode arrays (MEAs), i.e. common electrophysiology tools, to probe neuronal activity distributed over large populations of neurons or embryonic organs. Specific MEAs can also be used to build neural prostheses or implants to compensate function losses due to lesions or degeneration of parts of the central nervous system, such as retinal implants, which exhibit real promise as biocompatible neuroprostheses for in vivo neuronal stimulations. New electrode geometries enable high performance electrodes to surpass more conventional materials for such applications.
Timing performance of a Micro-Channel-Plate Photomultiplier Tube Bortfeldt, J.; Brunbauer, F.; David, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
960, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The spatial dependence of the timing performance of the R3809U-50 Micro-Channel-Plate PMT (MCP-PMT) by Hamamatsu was studied in high energy muon beams. Particle position information is provided by a ...GEM tracker telescope, while timing is measured relative to a second MCP-PMT, identical in construction. In the inner part of the circular active area (radius r<5.5 mm) the time resolution of the two MCP-PMTs combined is better than 10 ps. The signal amplitude decreases in the outer region due to less light reaching the photocathode, resulting in a worse time resolution. The observed radial dependence is in quantitative agreement with a dedicated simulation. With this characterization, the suitability of MCP-PMTs as t0 reference detectors has been validated.
Detonation nanodiamond monolayer coatings are exceptionally biocompatible substrates for in vitro cell culture. However, the ability of nanodiamond coatings of different origin, size, surface ...chemistry and morphology to promote neuronal adhesion, and the ability to pattern neurons with nanodiamonds have yet to be investigated.
Various nanodiamond coatings of different type are investigated for their ability to promote neuronal adhesion with respect to surface coating parameters and neurite extension. Nanodiamond tracks are patterned using photolithography and reactive ion etching.
Universal promotion of neuronal adhesion is observed on all coatings tested and analysis shows surface roughness to not be a sufficient metric to describe biocompatibility, but instead nanoparticle size and curvature shows a significant correlation with neurite extension. Furthermore, neuronal patterning is achieved with high contrast using patterned nanodiamond coatings down to at least 10 µm.
The results of nanoparticle size and curvature being influential upon neuronal adhesion has great implications towards biomaterial design, and the ability to pattern neurons using nanodiamond tracks shows great promise for applications both in vitro and in vivo.
•Immobilization of two olfactory receptors (M71 and OR7D4) onto diamond transducers is proposed.•Two different grafting procedures are monitored by EIS on BDD surfaces and micro-cantilevers.•Odorant ...detection is suggested in liquid phase using Laser Doppler read-out system.•M71 shows a good sensitivity to acetophenone and selectivity against 2-octanone.•OR7D4 sensor shows a good sensitivity to androstenone with selectivity against acetophenone and 2-octanone.
Two olfactory receptors (ORs), mouse M71 and chimpanzee OR7D4, were immobilized onto synthetic diamond transducers surfaces. 6His tagged M71 (6His-M71) was grafted using covalent attachment of nitriloacetic acid (NTA) as chelating agent, which could bind the 6His tagged receptor through nickel ions. OR7D4 was grafted through covalent bonding of hexanoic acid radical on diamond followed by EDC/NHS peptidic coupling to the receptor. Both grafting procedures were monitored by electrochemical impedance spectroscopy (EIS) on boron doped diamond (BDD) electrodes. Then the grafting protocols were applied to the surface of bulk diamond micro-cantilevers. The resulting sensors were assessed for odorant detection in the liquid phase using a Laser Doppler read-out system. The 6His-M71 based sensor was found to exhibit a good sensitivity to acetophenone, with a typical frequency shift near 100Hz for 1μM exposure, with a good selectivity against negative control 2-octanone. The OR7D4 based sensor showed a sensitivity of 200Hz for exposures to 1 or 10μM androstenone with a good selectivity against both non-ligands acetophenone and 2-octanone.
We report here on a new approach for the detection and identification of actinides ( 239 Pu, 241 Am, 244 Cm, etc). This approach is based on the use of a novel device consisting of a boron doped ...nanocrystalline diamond film deposited onto a silicon PIN diode alpha particle sensor. The actinides concentration is probed in situ in the measuring solution using a method based on electro-precipitation that can be carried out via the use of a doped diamond electrode. The device allows probing directly both alpha-particles activity and energy in liquid solutions. In this work, we address the optimization of the actinides electro-precipitation step onto the sensor. The approach is based on fine tuning the pH of the electrolyte, the nature of the supporting electrolytes (Na 2 SO 4 or NaNO 3 ), the electrochemical cell geometry, the current density value, the precipitation duration as well as the sensor surface area. The deposition efficiency was significantly improved with values reaching for instance up to 81.5% in the case of electro-precipitation of 5.96 Bq 241 Am on the sensor. The diamond/silicon sensor can be reused after measurement by performing a fast decontamination step at high yields ≥99%, where the 241 Am electro-precipitated layer is quickly removed by applying an anodic current (+2 mA · cm -2 for 10 minutes) to the boron doped nanocrystalline diamond electrode in aqueous solution. This study demonstrated that alpha-particle spectroscopic measurements could be made feasible for the first time in aqueous solutions after an electrochemical deposition process, with theoretical detections thresholds as low as 0.24 Bq · L -1 . We believe that this approach can be of very high interest for alpha-particle spectroscopy in liquids for actinides trace detection.
A new sensitive coating for surface acoustic wave (SAW) transducers based on diamond nano-particles functionalised with a zinc porphyrin complex is investigated for the detection of nitroaromatic ...vapours. The role of diamond nano-particles is to offer a stable sp
3 carbon porous matrix onto which the metalloporphyrin receptor is immobilised. This functionalised matrix can then be deposited by a layer-by-layer deposition method homogeneously on the transducer surface while featuring a high surface area. Good repeatability was obtained from sensor to sensor. The resulting sensors show a very high sensitivity of typically 120
Hz
ppb
−1 with a limit of detection (LOD) at 1
ppb level towards 2,4-dinitrotoluene (DNT) vapours, a tracer for explosive trinitrotoluene (TNT). The response is enhanced by more than a factor 10 when using diamond nano-particles as opposed to a transducer with only the metalloporphyrin complex deposited on the surface. The response time
t
90% is approximately 4
min and the sensor response is fully reversible. The cross-sensitivity of the sensor is low when exposed to polar compounds such as ethanol or moisture. Those results are encouraging towards the development of low cost portable explosive vapour detectors. Furthermore, the carbon terminated surface of diamond nano-particles offers wide opportunities for grafting other types or receptors for chemical or biological gravimetric detection.
Ammonia is a key component of many industrial processes where it is used in very high concentrations. The applications range from high quality steel production and fertiliser manufacture, to the ...refrigeration of food products and ice ring leisure facilities. Ammonia escapes have been identified as a large and serious problem by both government and industry. Simple and robust ammonia sensors for remote monitoring applications remain an area of continuous interest.
Polyaniline is a conducting polymer used in ‘electronic nose’ instrumentation and has been shown to be electronically sensitive to ammonia. In this paper, we report on the application of electrochemically-prepared polyaniline films for the measurement of gaseous ammonia at 1300
nm. This wavelength corresponds to a region of high optical transmission for optical fibres and is also compatible with telecom devices and technology. A simple and robust measurement system based on a standard telecom 1300
nm LED is described and remote sensing using 100
m of duplex multimode fibre is demonstrated.
Typically, the transmission of the polyaniline films at 1300
nm increases by approximately 1% in response to gaseous ammonia levels of 6
ppm in 50% RH. This represents the lower limit of detection in our study. Although initially the sensors react to the presence of ammonia very fast it takes over several hours for the output to reach the equilibrium. Clearly this is impractical however, it is possible to differentiate between different concentrations of ammonia by taking two readings at fixed intervals. A calibration curve for the sensors was obtained using two readings 15
s apart. The response time of the polyanaline films was found to be insensitive to the humidity variations in the range of 30–70% RH, however, over the 10–90% variation the changes were of the same order of magnitude as those induced by 6
ppm of ammonia.
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