scholarly journals MAPLE Assembled Acetylcholinesterase–Polyethylenimine Hybrid and Multilayered Interfaces for Toxic Gases Detection

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4265 ◽  
Author(s):  
Valentina Dinca ◽  
Cristian Viespe ◽  
Simona Brajnicov ◽  
Izabela Constantinoiu ◽  
Antoniu Moldovan ◽  
...  
Keyword(s):  
Pulsed Laser ◽  
Target System ◽  
Laser Evaporation ◽  
Average Roughness ◽  
Force Microscopy ◽  
Active Surfaces ◽  
Layered Coatings ◽  
Atomic Force ◽  
Deposition Processes ◽  
Materials Used

Developing a controlled method for obtaining hybrid enzymatic-based interfaces for sensing application require the use of a multiuse, reusable sensor. By controlling the interface characteristics in terms of the surface chemistry, thickness, and roughness, a tailored response toward various toxic compounds can be obtained, regarding both materials used as active surfaces and fabrication methods. Herein, we report a preliminary study on using a laser-based method (i.e., matrix-assisted pulsed laser evaporation, or MAPLE) for obtaining active polymeric–enzymatic interfaces as hybrid or layered coatings for detecting toxic vapors. The MAPLE fabrication consisted of the simultaneous alternating evaporation of layers of polyethylenimine (PEI) and acetylcholinesterase (AchE) in order to obtain active surfaces as both hybrid PEI-AchE and a PEI/AchE layered coating, respectively. The deposition processes of the polymer and enzyme were carried out using a double-target system and a Nd:YAG pulsed laser, operating at 0.45 J/cm2 fluences with a wavelength of 266 nm and a repetition rate of 10 Hz. Fourier transform infrared spectroscopy revealed no significant changes in the functional groups of both hybrid and layered coatings compared with the initial material. The thickness and roughness, as well as the morphologies of the coatings revealed by atomic force microscopy and scanning electron microscopy showed coatings thicker than two μm that had smooth surfaces and average roughness values below six nm. The sensors were tested with simulants for nerve gases and pesticides containing phosphonate ester groups, namely dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP), and a different sensitivity was shown to the selected chemical agents for each of the sensors. The best sensitivities for DMMP and DIMP obtained by using a PEI-AchE coated sensor are 65 kHz and 200 kHz, respectively, whereas the best sensitivity when using multilayered interfaces is 30 kHz and 10 KHz for DIMP and DMMP, respectively.

Matrix Assisted Pulsed Laser Evaporation of Poly (D, L) Lactic Acid Films

2004 ◽  
Vol 845 ◽  
Author(s):  
Timothy M. Patz ◽  
Anand Doraiswamy ◽  
Roger Narayan ◽  
Nicola Menegazzo ◽  
Christine Kranz ◽  
...  
Keyword(s):  
Thin Films ◽  
Lactic Acid ◽  
Photoelectron Spectroscopy ◽  
Pulsed Laser ◽  
Laser Evaporation ◽  
Absorption Bands ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tissue Interface

ABSTRACTWe have deposited poly (D, L lactic acid) (PDLLA) thin films using matrix assisted pulsed laser evaporation (MAPLE). FTIR spectroscopy revealed that the PDLLA had similar absorption bands to the dropcast material. X-ray photoelectron spectroscopy has shown that peaks corresponding to C-H, C-O and C=O represented 38.4, 30.1 and 31.4% of the C1s spectrum, respectively. XPS O1s analysis revealed that the O=C and O-C components make up 52 and 48 % of the O1s content. Atomic force microscopy revealed that MAPLE deposition provides smooth, continuous thin biomaterial films. These matrix assisted pulsed laser evaporation-deposited biomaterial thin films may serve to improve the implant/tissue interface.

Frequency and Temperature Dependence of Dielectric Properties of Orthorhombic HoMnO3 Thin Films

2014 ◽  
Vol 1025-1026 ◽  
pp. 427-431
Author(s):  
Ping Gao ◽  
Wei Zhang ◽  
Wei Tian Wang
Keyword(s):  
Dielectric Properties ◽  
Pulsed Laser ◽  
Signal Amplitude ◽  
Debye Model ◽  
Laser Deposition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cole Diagram

Orthorhombic HoMnO3 films were prepared epitaxially on Nb-doped SrTiO3 single crystal substrates by using pulsed laser deposition technique. The films showed perfectly a-axis crystallographic orientations. X-ray diffraction and atomic force microscopy were used to characterize the films. The complex dielectric properties were measured as functions of frequency (40 Hz~1 MHz) and temperature (80 K~300 K) with a signal amplitude of 50 mv. The respective dielectric relaxation peaks shifted to higher frequency as the measuring temperature increased, with the same development of real part of the complex permittivity. The cole-cole diagram was obtained according to the Debye model, and the effects of relaxation process were discussed.

Studies of Nanomechanical Properties of Pulsed Laser Deposited NbN films on Si Using Nanoindentation

2012 ◽  
Vol 1424 ◽  
Author(s):  
M. A. Mamun ◽  
A. H. Farha ◽  
Y. Ufuktepe ◽  
H. E. Elsayed-Ali ◽  
A. A. Elmustafa
Keyword(s):  
Thin Films ◽  
Pulsed Laser ◽  
Niobium Nitride ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Pile Up ◽  
Average Modulus

ABSTRACTNanomechanical and structural properties of pulsed laser deposited niobium nitride thin films were investigated using X-ray diffraction, atomic force microscopy, and nanoindentation. NbN film reveals cubic δ-NbN structure with the corresponding diffraction peaks from the (111), (200), and (220) planes. The NbN thin films depict highly granular structure, with a wide range of grain sizes that range from 15-40 nm with an average surface roughness of 6 nm. The average modulus of the film is 420±60 GPa, whereas for the substrate the average modulus is 180 GPa, which is considered higher than the average modulus for Si reported in the literature due to pile-up. The hardness of the film increases from an average of 12 GPa for deep indents (Si substrate) measured using XP CSM and load control (LC) modes to an average of 25 GPa measured using the DCM II head in CSM and LC modules. The average hardness of the Si substrate is 12 GPa.

Mechanical Interlocking on Leadframe Surface for Bondability of Au Wedge Bond

2016 ◽  
Vol 857 ◽  
pp. 79-82
Author(s):  
Roslina Ismail ◽  
Fuaida Harun ◽  
Azman Jalar ◽  
Shahrum Abdullah
Keyword(s):  
Optical Microscope ◽  
Bonding Process ◽  
Mechanical Interlocking ◽  
Average Roughness ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Morphologies ◽  
Scanning Electron ◽  
Effect Of Surface

This work is a contribution towards the understanding of wire bond integrity and reliability in relation to their microstructural and mechanical properties in semiconductor packaging.The effect of surface roughness and hardness of leadframe on the bondability of Au wedge bond still requires detail analysis. Two type of leadframes namely leadframe A and leadframe B were chosen and scanning electron microscope (SEM) and optical microscope were used to inspect the surface morphology of leadframes and the quality of created Au wedge bond after wire bonding process. It was found that there were significant differences in the surface morphologies between these two leadframes. The atomic force microscopy (AFM) which was utilized to measure the average roughness, Ra of lead finger confirms that leadframe A has the highest Ra with value of 166.46 nm compared to that of leadframe B with value of 85.89 nm. While hardness value of different lead finger from the selected leadframe A and B obtained using Vicker microhardness tester are 180.9 VH and 154.2VH respectively.

Pulsed Laser Deposition of Superconductor/Ferromagnetic YBa2Cu3Oy/SrTiO3/La2/3Sr1/3MnO3 Heterostructures

1999 ◽  
Vol 574 ◽  
Author(s):  
V. Trtík ◽  
F. Sánchez ◽  
C. Ferrater ◽  
M. Varela ◽  
L. Fábrega ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Complete Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Strip Geometry ◽  
Droplet Density ◽  
Scanning Electron ◽  
Deposition Conditions

AbstractYBa2Cu3Oy/SrTiO3/La2/3Sr1/3MnO3 heterostructures have been deposited on LaAlO3(001) and SrTiO3(001) substrates by pulsed laser deposition. First, the influence of deposition conditions on crystallinity and morphology of single LSMO films was examined. Results were used for preparation of heterostructures in tri-layer and cross-strip geometry. Cross-strip geometry was defined by direct shadow mask patterning. Different characterization techniques have been used to determine and correlate the heterostructure properties. A complete analysis of the crystal structure has been carried out with a four-circle difractometer. Morphology has been studied by scanning electron microscopy and atomic force microscopy in order to determine surface roughness and droplet density. Basic electrical properties of films have been determined.

Cross-Sectional Nanoindentation of Alumina Thin Films Deposited by Pulsed Laser Deposition Process

2006 ◽  
Author(s):  
Sudheer Neralla ◽  
Sergey Yarmolenko ◽  
Dhananjay Kumar ◽  
Devdas Pai ◽  
Jag Sankar
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
High Hardness ◽  
Deposition Process ◽  
Laser Deposition ◽  
Cross Sectional ◽  
Adhesion Properties ◽  
Force Microscopy ◽  
Atomic Force

Alumina is a widely used ceramic material due to its high hardness, wear resistance and dielectric properties. The study of phase transformation and its correlation to the mechanical properties of alumina is essential. In this study, interfacial adhesion properties of alumina thin films are studied using cross-sectional nanoindentation (CSN) technique. Alumina thin films are deposited at 200 and 700 °C, on Si (100) substrates with a weak Silica interface, using pulsed laser deposition (PLD) process. Effect of annealing on the surface morphology of the thin films is studied using atomic force microscopy. Xray diffraction studies revealed that alumina thin films are amorphous in nature at 200 °C and polycrystalline with predominant gamma alumina phase at 700 °C.

Growth of Carbon Nanotubes on Si Substrate Using Fe Catalyst Produced by Pulsed Laser Deposition

2008 ◽  
Vol 8 (11) ◽  
pp. 5748-5752
Author(s):  
S. Krishnamurthy ◽  
T. Donnelly ◽  
N. McEvoy ◽  
W. Blau ◽  
J. G. Lunney ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Pulsed Laser Deposition ◽  
Chemical Vapour ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Force Microscopy ◽  
Fe Catalyst ◽  
Atomic Force ◽  
Catalytic Nanoparticles ◽  
Size Controlled

We report the growth of carbon nanotubes on the size controlled iron catalytic nanoparticles. The nanotubes were grown by thermal chemical vapour deposition (CVD) in the temperature range 600–850 °C. The Fe films were deposited on silicon by pulsed laser deposition in vacuum. Atomic force microscopy measurements were performed on the catalytic nanoparticles. The topography of the catalytic nanoparticles shows the homogenous distribution of Fe catalyst. We observe the nanotubes are produced only at temperatures between 650 and 800 °C, and within this narrow temperature regime the yield of nanotubes reaches a maximum around 750 °C and then declines. Raman measurements illustrate a high G/D peak ratio indicating good nanotube quality. By further defining the size of the catalyst the diameter of these carbon nanotubes can be controlled.

Influence of Post Growth Annealing on the Optical Properties of Gallium Nitride Films Grown by Pulsed Laser Deposition

2012 ◽  
Vol 1432 ◽  
Author(s):  
M. Baseer Haider ◽  
M. F. Al-Kuhaili ◽  
S. M. A. Durrani ◽  
Imran Bakhtiari
Keyword(s):  
Thin Films ◽  
Gallium Nitride ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Nitrogen Atmosphere ◽  
Laser Deposition ◽  
Optical Measurements ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

Abstract:Gallium nitride thin films were grown by pulsed laser deposition. Subsequently, post-growth annealing of the samples was performed at 400, and 600 oC in the nitrogen atmosphere. Surface morphology of the as-grown and annealed samples was performed by atomic force microscopy, surface roughness of the films improved after annealing. Chemical analysis of the samples was performed using x-ray photon spectroscopy, stoichiometric Gallium nitride thin films were obtained for the samples annealed at 600 oC. Optical measurements of the samples were performed to investigate the effect of annealing on the band gap and optical constants the films.

scholarly journals In Situ Initial Growth Studies of SrTiO3 on SrTiO3 by Time Resolved High Pressure RHEED

1998 ◽  
Vol 526 ◽  
Author(s):  
Gertjan Koster ◽  
Guus J.H.M. Rijnders ◽  
Dave H.A. Blank ◽  
Horst Rogalla
Keyword(s):  
High Pressure ◽  
Pulsed Laser ◽  
High Energy ◽  
Initial Growth ◽  
Time Resolved ◽  
Force Microscopy ◽  
Atomic Force ◽  
Different Temperatures ◽  
Substrate Surfaces

AbstractThe initial growth of pulsed laser deposited SrTiO3 on SrTiO3 has been studied using high pressure Reflection High Energy Electron Diffraction (RHEED) and Atomic Force Microscopy (AFM). For this, we developed a Pulsed Laser Deposition (PLD)-RHEED system, with the possibility to study the growth and to monitor the growth rates, in situ, at typical PLD pressures (10-50 Pa). Using perfect single crystal SrTiO3 substrate surfaces, we observe true 2D intensity oscillations at different temperatures. Simultaneously, information on the diffusion of the deposited material on the surface could be extracted from the relaxation of the intensity after each laser pulse. The characteristic times depend on pressure and temperature as well as the 2D coverage during growth.

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