In this work, the ternary titanium, copper and silver (Ti-Cu-Ag) system is investigated as a pote... more In this work, the ternary titanium, copper and silver (Ti-Cu-Ag) system is investigated as a potential candidate for the production of mechanically robust biomedical thin films. The coatings are produced by physical vapor deposition-magnetron sputtering (MS-PVD). The composite thin films are deposited on a silicon (100) substrate. The ratio between Ti and Cu was approximately kept one, with the variation of the Ag content between 10 and 35 at.%, while the power on the targets is changed during each deposition to get the desired Ag content. Thin film characterization is performed by x-ray diffraction (XRD), nanoindentation (modulus and hardness) and Atomic force microscopy to determine the surface topography. The residual stresses are measured by focused ion beam and digital image correlation method (FIB-DIC). The produced Ti-Cu-Ag thin films appear to be smooth, uniformly thick and exhibit amorphous structure for the Ag contents lower than 25 at.%, with a transition to partially cry...
Silver-based low-emissivity (low-E) coatings are applied on architectural glazing to cost-effecti... more Silver-based low-emissivity (low-E) coatings are applied on architectural glazing to cost-effectively reduce heat losses, as they generally consist of dielectric/Ag/dielectric multilayer stacks, where the thin Ag layer reflects long- wavelength infrared (IR), while the dielectric layers both protect the Ag and act as an anti-reflective barrier. The architecture of the multilayer stack influences its mechanical properties and it is strongly dependent on the residual stress distribution in the stack. Residual stress evaluation by combining focused ion beam (FIB) milling and digital image correlation (DIC), using the micro-ring core configuration (FIB-DIC), offers micron-scale lateral resolution and provides information about the residual stress variation with depth, i.e., it allows depth profiling for both equibiaxial and non-equibiaxial stress distributions and hence can be effectively used to characterize low-E coatings. In this work, we propose an innovative approach to improve the...
Deux revêtements à base nickel obtenus par des bains réducteurs, l’un brut et l’autre ayant subi ... more Deux revêtements à base nickel obtenus par des bains réducteurs, l’un brut et l’autre ayant subi un traitement thermique sont étudiés. L’essai d’indentation a été mis en œuvre pour caractériser la dureté et le module de Young de ces dépôts. Les résultats montrent une bonne homogénéité des propriétés mécaniques dans l’épaisseur du revêtement, alors que le traitement thermique a eu pour effet d’augmenter sa dureté et son module de façon significative. Les contraintes résiduelles dans les revêtements sont étudiées par la méthode du micro anneau incrémental. Les contraintes calculées sont faibles, dispersées et ne semblent pas dépendre du traitement thermique. En l’absence de contraintes résiduelles avant et après traitement thermique, les variations de propriétés mécaniques ont été attribuées à la modification microstructurale du revêtement et à la précipitation de phases dures.
Accurate estimation of fracture behavior of commercial LiMn 2 O 4 particles is of great importanc... more Accurate estimation of fracture behavior of commercial LiMn 2 O 4 particles is of great importance to predict the performance and lifetime of a battery. The present study compares two different microscale techniques to quantify the fracture toughness of LiMn 2 O 4 particles embedded in an epoxy matrix. The first technique uses focused ion beam (FIB) milled micro pillars that are subsequently tested using the nanoindentation technique. The pillar geometry, critical load at pillar failure, and cohesive FEM simulations are then used to compute the fracture toughness. The second technique relies on the use of atomic force microscopy (AFM) to measure the crack opening displacement (COD) and subsequent application of Irwin's near field theory to measure the mode-I crack tip toughness of the material. Results show pillar splitting method provides a fracture toughness value of~0.24 MPa.m 1/2 , while COD measurements give a crack tip toughness of~0.81 MPa.m 1/2. The comparison of fracture toughness values with the estimated value on the reference LiMn 2 O 4 wafer reveals that micro pillar technique provides measurements that are more reliable than the COD method. The difference is associated with ease of experimental setup, calculation simplicity, and little or no influence of external factors as associated with the COD measurements.
The present work deals with a new technique to produce complex micro- and nano-scale patterns wit... more The present work deals with a new technique to produce complex micro- and nano-scale patterns with high accuracy by FIB micro machining. The proposed method is related to the production of stream file, which is optimized through a software interface. A unique sampling approach is used to optimize the conversion from a 3D meshed CAD object to the focused ion beam (FIB) digital to analogue converter (DAC). The method uses a novel scan strategy, sensitive to the pattern local geometry and size, to define the optimal ion beam path, dwell time and the scanning pitch. This not only allows to minimize the redeposition but also to obtain accurate and scalable milling routines. In order to show the applicability of the method, a hemisphere and a pyramid shape are milled and compared to the shapes obtained using the conventional techniques. Results show that the method is very effective in producing complex shapes while overcoming the detrimental effect of conventional raster/serpentine FIB strategies, such as redeposition. Lastly, a fish-net structure with a pitch of ∼200nm as well as a series of truncated cones with sub-micrometrical details are realized to show the potential impact of this new method. Results show that a spatial resolution of less than 100nm is achievable with the help of this method.
The progression of the junior doctor contract negotiations within the National Health Service (NH... more The progression of the junior doctor contract negotiations within the National Health Service (NHS) has been widely reported. We aim to provide a comprehensive summary of the current state of affairs with the contract negotiations and hope to inform those who may not be familiar with the situation affecting junior doctors in the NHS.
Novel high speed nanoindentation data is reported for 0% and 100% state of charge (SoC) for the s... more Novel high speed nanoindentation data is reported for 0% and 100% state of charge (SoC) for the spinal Li x Mn2O4 material. The article also includes the load/displacement data for different SoC highlighting the displacement bursts corresponding to the pillar splitting for fracture toughness evaluation. For more details, please see the article; Mughal et al. (2016) [1].
ABSTRACT Currently, flapping wing unmanned aerial vehicles (a.k.a., ornithopters or robotic birds... more ABSTRACT Currently, flapping wing unmanned aerial vehicles (a.k.a., ornithopters or robotic birds) sustain very short duration flight due to limited on-board energy storage capacity. Therefore, energy harvesting elements, such as flexible solar cells, need to be used as materials in critical components, such as wing structures, to increase operational performance. In this paper, we describe a layered fabrication method that was developed for realizing multifunctional composite wings for a unique robotic bird we developed, known as Robo Raven, by creating compliant wing structure from flexible solar cells. The deformed wing shape and aerodynamic lift/thrust loads were characterized throughout the flapping cycle to understand wing mechanics. A multifunctional performance analysis was developed to understand how integration of solar cells into the wings influences flight performance under two different operating conditions: (1) directly powering wings to increase operation time, and (2) recharging batteries to eliminate need for external charging sources. The experimental data is then used in the analysis to identify a performance index for assessing benefits of multifunctional compliant wing structures. The resulting platform, Robo Raven III, was the first demonstration of a robotic bird that flew using energy harvested from solar cells. We developed three different versions of the wing design to validate the multifunctional performance analysis. It was also determined that residual thrust correlated to shear deformation of the wing induced by torsional twist, while biaxial strain related to change in aerodynamic shape correlated to lift. It was also found that shear deformation of the solar cells induced changes in power output directly correlating to thrust generation associated with torsional deformation. Thus, it was determined that multifunctional solar cell wings may be capable of three functions: (1) lightweight and flexible structure to generate aerodynamic forces, (2) energy harvesting to extend operational time and autonomy, and (3) sensing of an aerodynamic force associated with wing deformation.
2011 IEEE Long Island Systems, Applications and Technology Conference, 2011
... The software used to control the machine came from Arduino free software project. ... These d... more ... The software used to control the machine came from Arduino free software project. ... These days most robotics applications are found in manufacturing industry. This is destined to be changed as advancements in artificial intelligence prevail. ...
ABSTRACTProtein adsorption is the first phenomenon which occurs at nanoscale level when a given s... more ABSTRACTProtein adsorption is the first phenomenon which occurs at nanoscale level when a given surface came into contact with a living fluid cell such as blood. Investigation of this adsorption at nanoscale provides useful information about kinetics and mechanism of conformation of proteins on a given surface. The present study investigates the adsorption of proteins using tapping/intermittent mode atomic force microscopy (T-AFM). The approach taken here is that hydrogenated amorphous carbon coating (a-C:H) is used as a model surface because it is amorphous, smooth, inert and hydrophobic. Two proteins namely albumin and fibrinogen in phosphate buffer (PBS) and de-ionized water are drop casted to study the adsorption kinetics. First and second resonance AFM data was used to investigate the adsorbed layer of proteins. AFM force curve and scratch experiment were used to verify the adhesion and thickness of the adsorbed layer. Combination of height, phase images along with the AFM forc...
ABSTRACT The Physical Vapor Deposition (PVD) is a technique in which metal or metal alloy vapors ... more ABSTRACT The Physical Vapor Deposition (PVD) is a technique in which metal or metal alloy vapors are deposited on the surface of the tools in a vacuum chamber. The positioning of the tools i.e. fixture and loading factors (% area of the chamber filled with tools) influence in the flow of the vapors in the chamber. This results in a significant effect on the coating characteristics which affect the film properties. Nano Composite Coatings i.e. AlTiN/Si3N4 (nACo) or AlCrN/Si3N4 (nACRo) deposited by the PVD technique show superior hardness, toughness, heat and oxidation resistance. The adhesion and diffusion of these Nano structured films on substrate depend on proper surface cleaning steps and loading factors. In present work, nACo and nACRo coatings were done by changing the loading factors (50% to 75%) for coating. These coated samples were characterized and the tribological, mechanical and wear properties were studied. It was observed that; fixture, surface cleaning steps of substrate and vacuum surface areas (loading factors) have influenced the adhesion and thickness properties of the coated films. The 75% loading factors greatly enhance the efficiency of tools coated with both nACo and nACRo structured films.
Journal of Biomedical Materials Research Part A, 2012
Bioresorbable polymers have been widely investigated as materials exhibiting significant potentia... more Bioresorbable polymers have been widely investigated as materials exhibiting significant potential for successful application in the fields of tissue engineering and drug delivery. Further to the ability to control degradation, surface engineering of polymers has been highlighted as a key method central to their development. Previous work has demonstrated the ability of electron beam (e-beam) technology to control the degradation profiles and bioresorption of a number of commercially relevant bioresorbable polymers (poly-l-lactic acid (PLLA), Llactide/DL-lactide co-polymer (PLDL) and poly(lactic-co-glycolic acid (PLGA)). This work investigates the further potential of ebeam technology to impart added biofunctionality through the manipulation of polymer (PLLA) surface properties. PLLA samples were subjected to e-beam treatments in air, with varying beam energies and doses. Surface characterization was then performed using contact angle analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and atomic force microscopy. Results demonstrated a significant increase in surface wettability post e-beam treatment. In correlation with this, XPS data showed the introduction of oxygen-containing functional groups to the surface of PLLA. Raman spectroscopy indicated chain scission in the near surface region of PLLA (as predicted). However, e-beam effects on surface properties were not shown to be dependent on beam energy or dose. E-beam irradiation did not seem to affect the surface roughness of PLLA as a direct consequence of the treatment. V
... The software used to control the machine came from Arduino free software project. ... These d... more ... The software used to control the machine came from Arduino free software project. ... These days most robotics applications are found in manufacturing industry. This is destined to be changed as advancements in artificial intelligence prevail. ...
In this work, the ternary titanium, copper and silver (Ti-Cu-Ag) system is investigated as a pote... more In this work, the ternary titanium, copper and silver (Ti-Cu-Ag) system is investigated as a potential candidate for the production of mechanically robust biomedical thin films. The coatings are produced by physical vapor deposition-magnetron sputtering (MS-PVD). The composite thin films are deposited on a silicon (100) substrate. The ratio between Ti and Cu was approximately kept one, with the variation of the Ag content between 10 and 35 at.%, while the power on the targets is changed during each deposition to get the desired Ag content. Thin film characterization is performed by x-ray diffraction (XRD), nanoindentation (modulus and hardness) and Atomic force microscopy to determine the surface topography. The residual stresses are measured by focused ion beam and digital image correlation method (FIB-DIC). The produced Ti-Cu-Ag thin films appear to be smooth, uniformly thick and exhibit amorphous structure for the Ag contents lower than 25 at.%, with a transition to partially cry...
Silver-based low-emissivity (low-E) coatings are applied on architectural glazing to cost-effecti... more Silver-based low-emissivity (low-E) coatings are applied on architectural glazing to cost-effectively reduce heat losses, as they generally consist of dielectric/Ag/dielectric multilayer stacks, where the thin Ag layer reflects long- wavelength infrared (IR), while the dielectric layers both protect the Ag and act as an anti-reflective barrier. The architecture of the multilayer stack influences its mechanical properties and it is strongly dependent on the residual stress distribution in the stack. Residual stress evaluation by combining focused ion beam (FIB) milling and digital image correlation (DIC), using the micro-ring core configuration (FIB-DIC), offers micron-scale lateral resolution and provides information about the residual stress variation with depth, i.e., it allows depth profiling for both equibiaxial and non-equibiaxial stress distributions and hence can be effectively used to characterize low-E coatings. In this work, we propose an innovative approach to improve the...
Deux revêtements à base nickel obtenus par des bains réducteurs, l’un brut et l’autre ayant subi ... more Deux revêtements à base nickel obtenus par des bains réducteurs, l’un brut et l’autre ayant subi un traitement thermique sont étudiés. L’essai d’indentation a été mis en œuvre pour caractériser la dureté et le module de Young de ces dépôts. Les résultats montrent une bonne homogénéité des propriétés mécaniques dans l’épaisseur du revêtement, alors que le traitement thermique a eu pour effet d’augmenter sa dureté et son module de façon significative. Les contraintes résiduelles dans les revêtements sont étudiées par la méthode du micro anneau incrémental. Les contraintes calculées sont faibles, dispersées et ne semblent pas dépendre du traitement thermique. En l’absence de contraintes résiduelles avant et après traitement thermique, les variations de propriétés mécaniques ont été attribuées à la modification microstructurale du revêtement et à la précipitation de phases dures.
Accurate estimation of fracture behavior of commercial LiMn 2 O 4 particles is of great importanc... more Accurate estimation of fracture behavior of commercial LiMn 2 O 4 particles is of great importance to predict the performance and lifetime of a battery. The present study compares two different microscale techniques to quantify the fracture toughness of LiMn 2 O 4 particles embedded in an epoxy matrix. The first technique uses focused ion beam (FIB) milled micro pillars that are subsequently tested using the nanoindentation technique. The pillar geometry, critical load at pillar failure, and cohesive FEM simulations are then used to compute the fracture toughness. The second technique relies on the use of atomic force microscopy (AFM) to measure the crack opening displacement (COD) and subsequent application of Irwin's near field theory to measure the mode-I crack tip toughness of the material. Results show pillar splitting method provides a fracture toughness value of~0.24 MPa.m 1/2 , while COD measurements give a crack tip toughness of~0.81 MPa.m 1/2. The comparison of fracture toughness values with the estimated value on the reference LiMn 2 O 4 wafer reveals that micro pillar technique provides measurements that are more reliable than the COD method. The difference is associated with ease of experimental setup, calculation simplicity, and little or no influence of external factors as associated with the COD measurements.
The present work deals with a new technique to produce complex micro- and nano-scale patterns wit... more The present work deals with a new technique to produce complex micro- and nano-scale patterns with high accuracy by FIB micro machining. The proposed method is related to the production of stream file, which is optimized through a software interface. A unique sampling approach is used to optimize the conversion from a 3D meshed CAD object to the focused ion beam (FIB) digital to analogue converter (DAC). The method uses a novel scan strategy, sensitive to the pattern local geometry and size, to define the optimal ion beam path, dwell time and the scanning pitch. This not only allows to minimize the redeposition but also to obtain accurate and scalable milling routines. In order to show the applicability of the method, a hemisphere and a pyramid shape are milled and compared to the shapes obtained using the conventional techniques. Results show that the method is very effective in producing complex shapes while overcoming the detrimental effect of conventional raster/serpentine FIB strategies, such as redeposition. Lastly, a fish-net structure with a pitch of ∼200nm as well as a series of truncated cones with sub-micrometrical details are realized to show the potential impact of this new method. Results show that a spatial resolution of less than 100nm is achievable with the help of this method.
The progression of the junior doctor contract negotiations within the National Health Service (NH... more The progression of the junior doctor contract negotiations within the National Health Service (NHS) has been widely reported. We aim to provide a comprehensive summary of the current state of affairs with the contract negotiations and hope to inform those who may not be familiar with the situation affecting junior doctors in the NHS.
Novel high speed nanoindentation data is reported for 0% and 100% state of charge (SoC) for the s... more Novel high speed nanoindentation data is reported for 0% and 100% state of charge (SoC) for the spinal Li x Mn2O4 material. The article also includes the load/displacement data for different SoC highlighting the displacement bursts corresponding to the pillar splitting for fracture toughness evaluation. For more details, please see the article; Mughal et al. (2016) [1].
ABSTRACT Currently, flapping wing unmanned aerial vehicles (a.k.a., ornithopters or robotic birds... more ABSTRACT Currently, flapping wing unmanned aerial vehicles (a.k.a., ornithopters or robotic birds) sustain very short duration flight due to limited on-board energy storage capacity. Therefore, energy harvesting elements, such as flexible solar cells, need to be used as materials in critical components, such as wing structures, to increase operational performance. In this paper, we describe a layered fabrication method that was developed for realizing multifunctional composite wings for a unique robotic bird we developed, known as Robo Raven, by creating compliant wing structure from flexible solar cells. The deformed wing shape and aerodynamic lift/thrust loads were characterized throughout the flapping cycle to understand wing mechanics. A multifunctional performance analysis was developed to understand how integration of solar cells into the wings influences flight performance under two different operating conditions: (1) directly powering wings to increase operation time, and (2) recharging batteries to eliminate need for external charging sources. The experimental data is then used in the analysis to identify a performance index for assessing benefits of multifunctional compliant wing structures. The resulting platform, Robo Raven III, was the first demonstration of a robotic bird that flew using energy harvested from solar cells. We developed three different versions of the wing design to validate the multifunctional performance analysis. It was also determined that residual thrust correlated to shear deformation of the wing induced by torsional twist, while biaxial strain related to change in aerodynamic shape correlated to lift. It was also found that shear deformation of the solar cells induced changes in power output directly correlating to thrust generation associated with torsional deformation. Thus, it was determined that multifunctional solar cell wings may be capable of three functions: (1) lightweight and flexible structure to generate aerodynamic forces, (2) energy harvesting to extend operational time and autonomy, and (3) sensing of an aerodynamic force associated with wing deformation.
2011 IEEE Long Island Systems, Applications and Technology Conference, 2011
... The software used to control the machine came from Arduino free software project. ... These d... more ... The software used to control the machine came from Arduino free software project. ... These days most robotics applications are found in manufacturing industry. This is destined to be changed as advancements in artificial intelligence prevail. ...
ABSTRACTProtein adsorption is the first phenomenon which occurs at nanoscale level when a given s... more ABSTRACTProtein adsorption is the first phenomenon which occurs at nanoscale level when a given surface came into contact with a living fluid cell such as blood. Investigation of this adsorption at nanoscale provides useful information about kinetics and mechanism of conformation of proteins on a given surface. The present study investigates the adsorption of proteins using tapping/intermittent mode atomic force microscopy (T-AFM). The approach taken here is that hydrogenated amorphous carbon coating (a-C:H) is used as a model surface because it is amorphous, smooth, inert and hydrophobic. Two proteins namely albumin and fibrinogen in phosphate buffer (PBS) and de-ionized water are drop casted to study the adsorption kinetics. First and second resonance AFM data was used to investigate the adsorbed layer of proteins. AFM force curve and scratch experiment were used to verify the adhesion and thickness of the adsorbed layer. Combination of height, phase images along with the AFM forc...
ABSTRACT The Physical Vapor Deposition (PVD) is a technique in which metal or metal alloy vapors ... more ABSTRACT The Physical Vapor Deposition (PVD) is a technique in which metal or metal alloy vapors are deposited on the surface of the tools in a vacuum chamber. The positioning of the tools i.e. fixture and loading factors (% area of the chamber filled with tools) influence in the flow of the vapors in the chamber. This results in a significant effect on the coating characteristics which affect the film properties. Nano Composite Coatings i.e. AlTiN/Si3N4 (nACo) or AlCrN/Si3N4 (nACRo) deposited by the PVD technique show superior hardness, toughness, heat and oxidation resistance. The adhesion and diffusion of these Nano structured films on substrate depend on proper surface cleaning steps and loading factors. In present work, nACo and nACRo coatings were done by changing the loading factors (50% to 75%) for coating. These coated samples were characterized and the tribological, mechanical and wear properties were studied. It was observed that; fixture, surface cleaning steps of substrate and vacuum surface areas (loading factors) have influenced the adhesion and thickness properties of the coated films. The 75% loading factors greatly enhance the efficiency of tools coated with both nACo and nACRo structured films.
Journal of Biomedical Materials Research Part A, 2012
Bioresorbable polymers have been widely investigated as materials exhibiting significant potentia... more Bioresorbable polymers have been widely investigated as materials exhibiting significant potential for successful application in the fields of tissue engineering and drug delivery. Further to the ability to control degradation, surface engineering of polymers has been highlighted as a key method central to their development. Previous work has demonstrated the ability of electron beam (e-beam) technology to control the degradation profiles and bioresorption of a number of commercially relevant bioresorbable polymers (poly-l-lactic acid (PLLA), Llactide/DL-lactide co-polymer (PLDL) and poly(lactic-co-glycolic acid (PLGA)). This work investigates the further potential of ebeam technology to impart added biofunctionality through the manipulation of polymer (PLLA) surface properties. PLLA samples were subjected to e-beam treatments in air, with varying beam energies and doses. Surface characterization was then performed using contact angle analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and atomic force microscopy. Results demonstrated a significant increase in surface wettability post e-beam treatment. In correlation with this, XPS data showed the introduction of oxygen-containing functional groups to the surface of PLLA. Raman spectroscopy indicated chain scission in the near surface region of PLLA (as predicted). However, e-beam effects on surface properties were not shown to be dependent on beam energy or dose. E-beam irradiation did not seem to affect the surface roughness of PLLA as a direct consequence of the treatment. V
... The software used to control the machine came from Arduino free software project. ... These d... more ... The software used to control the machine came from Arduino free software project. ... These days most robotics applications are found in manufacturing industry. This is destined to be changed as advancements in artificial intelligence prevail. ...
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Papers by zeeshan mughal