Papers by Dipankar Choudhury
International Journal of Precision Engineering and Manufacturing, 2013
Surface texture technique increases the tribological capability and performance of bearing surfac... more Surface texture technique increases the tribological capability and performance of bearing surfaces. This technology has a number of applications, including car engines and golf balls. However, the use of texture surface in artificial hip joints has not been adequately explored. The aim of the study is to investigate the effects of plateau honed surfaces on the tribological performance of metal-on-metal hip joints. Four sets of different plateau honed surfaces and a set of non-textured surface were investigated on a friction simulator with a lubricant having similar viscosity of pseudo-synovial fluid. The results showed 50% and 38% reductions in static and dynamic friction coefficient, respectively, for a honed surface (honed surface 3) compared with those of a non-textured surface after 1 million cycles. There was a number of wear signs, including adhesive and fatigue wear in all of the experimental surfaces. Nevertheless, the wear signs in the honed surface 3 were minor. Lubrication film thickness was thicker, and third body abrasive wear assumed to reduce in the honed surface since wear debris removed through honed channel. Therefore, the performance of a well-designed plateau-honed surface is significant in tribological aspects of metal-on-metal hip joints.
Tribology Transactions, 2015
ABSTRACT Diamond like carbon (DLC) and micro dimple are two potential surface modification techni... more ABSTRACT Diamond like carbon (DLC) and micro dimple are two potential surface modification techniques that are extensively studied to be utilized into biotribological interfaces in order to reduce friction coefficient and wear rate. However, in situ observation of bovine serum lubricated DLC and micro dimpled surface contact are not well understood yet. In this study, a DLC coated and a micro dimpled steel ball rubbed against the Cr coated glass disk, where 25% bovine serum was used as a lubricant, and the temperature was maintained at 370 C. The behaviors of interface were captured using an optical interferometry and the friction coefficients were measured using a torque sensor simultaneously. The experimental results reveal that DLC/glass sliding is scuffling-free, having lowered friction coefficient, however the lubrication film formation is insignificant. On the other hand, the dimples retained lubrication and as a result, the wear of the glass disk were minimized, however friction coefficient were not reduced. Therefore, the DLC and micro dimpled individually have few improved tribological features, but their combination should be considered for maximizing the performances.
Ceramics International, 2015
Ti-6Al-4V is widely used for arthroprosthe Q2 ses, particularly in metal-on-metal (MoM) hip joint... more Ti-6Al-4V is widely used for arthroprosthe Q2 ses, particularly in metal-on-metal (MoM) hip joints. In spite of the suitable wear and corrosion resistance, metallic wear particles and metal ion release occur on a large timescale. In addition, metal ion levels in patients' blood and urine often reportedly increase according to clinical data. Neurological disease, inflammatory response and cell necrosis can potentially develop consequently. The aim of this research is to fabricate a thin, hard film coating on Ti-6Al-4V in order to improve mechanical properties, such as the adhesion strength, surface hardness and surface roughness of Ti-6Al-4V, which should lead to substrate biocompatibility mitigation through reduced debris production, ion release and cytotoxicity. Physical vapor deposition (PVD) magnetron sputtering treatment is applied to obtain an enriched tantalum oxide (Ta-O) thin film coating. In this regard, pure tantalum (Ta) as a biocompatible metal is deposited atop Ti-6Al-4V substrate in the presence of oxygen gas and different parameter conditions, including substrate temperature, argon flow rate, oxygen flow rate and DC power. The results indicate that the surface hardness and surface roughness of the -O coated substrate significantly improve compared to uncoated substrate. The adhesion strength between Ta-O thin film and substrate is examined using a micro scratch tester, and maximum adhesion of 2500 mN is achieved. .my (Ahmed.A.D. Sarhan). Please cite this article as: B. Rahmati, et al., Development of tantalum oxide (Ta-O) thin film coating on biomedical Ti-6Al-4V alloy to enhance mechanical properties and biocompatibility, Ceramics International (2015), http://dx.
Science and Technology of Advanced Materials, 2015
The concentration of biological components of synovial fluid (such as albumin, globulin, hyaluron... more The concentration of biological components of synovial fluid (such as albumin, globulin, hyaluronic acid, and lubricin) varies between healthy persons and osteoarthritis (OA) patients. The aim of the present study is to compare the effects of such variation on tribological performance in a simulated hip joint model. The study was carried out experimentally by utilizing a pin-on-disk simulator on ceramic-on-ceramic (CoC) and ceramic-on-polyethylene (CoP) hip joint implants. The experimental results show that both friction and wear of artificial joints fluctuate with the concentration level of biological components. Moreover, the performance also varies between material combinations. Wear debris sizes and shapes produced by ceramic and polyethylene were diverse. We conclude that the biological components of synovial fluid and their concentrations should be considered in order to select an artificial hip joint to best suit that patient.
Science and Technology of Advanced Materials, 2015
Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is l... more Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize and collate findings of the recent demonstrations on debris characterization and their biological response that influences the occurrence in implant migration. A systematic review of peer-reviewed literature is performed, based on inclusion and exclusion criteria addressing mainly debris isolation, characterization, and biologic responses. Results show that debris characterization largely depends on their appropriate and accurate isolation protocol. The particles are found to be non-uniform in size and non-homogeneously distributed into the periprosthetic tissues. In addition, the sizes, shapes, and volumes of the particles are influenced by the types of joints, bearing geometry, material combination, and lubricant. Phagocytosis of wear debris is size dependent; high doses of submicron-sized particles induce significant level of secretion of bone resorbing factors. However, articles on wear debris from engineered surfaces (patterned and coated) are lacking. The findings suggest considering debris morphology as an important parameter to evaluate joint simulator and newly developed implant materials.
International Journal of Surface Science and Engineering
Albumin and globulin proteins are dominant protein components in synovial fluid, and play importa... more Albumin and globulin proteins are dominant protein components in synovial fluid, and play important roles in the lubrication mechanism of joint prostheses. The present study investigated the lubricating ability of albumin and globulin on ceramic-on-polyethylene joint implants. A pin-on-disk tribometer was used for friction tests where the experimental condition was replicated with a simulated hip joint condition. The experiment was conducted under three lubricating conditions: bovine synovial fluid (BSF), albumin and globulin. Mechanical properties of specimens and physical properties of lubricant were measured before and after the tests. The experimental results show that albumin yielded a lower friction coefficient as compared to globulin. However, both exhibited a higher friction coefficient and wear rate than that of bovine synovial fluid. This study suggests that further tribological investigations on major biological components of synovial fluid should be carried out, which wi...
Issues: Micro dimple is an advanced surface modification technique for enhancing tribological per... more Issues: Micro dimple is an advanced surface modification technique for enhancing tribological performances. However, fabrication process of micro dimple surface can have an impact in mechanical properties. The aim of the study is to identify whether there is any changes in hardness of textured surface due to the machining process and geometrical parameters. The machining process usually increases surface hardness and the geometrical parameter possibly decreases surface hardness. Method: A micro tool was utilised to fabricate a set of defined dimples on artificial hip joint heads (stainless steel). Two of the dimpled heads were coated with diamond like carbon (DLC) and tetrahedral amorphous carbon (TaC), respectively. Hardness was measured focused on two spots (zone 1: 10 µm from the dimple edge, Zone 2: at least 1 mm distance from dimple; n=6) to each of the samples by using a Dynamic micro intender. An EDX analysis was performed to inspect any foreign particle from the tool bits du...
Diamond like Carbon (DLC) is a carbon based material with high aspect for use in orthopaedic impl... more Diamond like Carbon (DLC) is a carbon based material with high aspect for use in orthopaedic implants because of its very low friction and wear rate. The micro dimple surface technique is one of the most advanced surface modification techniques available for the optimisation of tribological performance. A DLC coated micro dimple could bring the benefit of both techniques, thus could perform as a very effective interface to the artificial hip joints. We fabricated a defined dimple (diameter 300±10 µm, depth 80±5 µm, and spacing 0.5±0.05 mm) on stainless steel (SS) heads and coated with DLC and tetrahedral amorphous carbon (TaC). Five set of hip joint heads such as Non-dimpled CrCoMo, Dimpled SS, Non-dimpled DLC, Dimpled DLC and Dimpled TaC were tested on a ceramic cup by using a newly built pendulum hip joint simulator. The experiment was repeated ten times whereas bovine serum (25%) was used as a lubricant, and temperature was maintained at 37o C. The changes in surface roughness an...
Issues: Diamond like carbon (DLC) is a promising material in many engineering interfaces due to i... more Issues: Diamond like carbon (DLC) is a promising material in many engineering interfaces due to its excellent tribological performance. Very recently, it has been extensively tested as biotribological surfaces, and reported to have very lower friction and wear. However, very little studies have been carried out identifying its lubrication mechanism (film thickness) under a bovine serum lubrication mechanism. Therefore, the aim of the study is to understand the lubrication mechanism of DLC to a simulated hip joints condition. Method: A spherical head was manufactured to a diameter of 25 mm from a stainless steel bar, and polished to a mirror type surface finishing. Then, these have been coated with DLC by using a physical vapour depositing. Hardness, elasticity, wettability and surface roughness profiles were measured prior to the tribology test. In the tribology test, the DLC coated ball rubbed against Cr coated glass disk, where 25% bovine serum was used a lubricant and temperature...
A Study on Multilayer Diamond like Carbon for Artificial Hip Joint Interface Dipankar Choudhury1,... more A Study on Multilayer Diamond like Carbon for Artificial Hip Joint Interface Dipankar Choudhury1, Takehiro Morita2, Kazuhiro Nakashima2,3, Yoshinori Sawae2,3 1. Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 616 69 Brno, Czech Republic 2. Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan 3. Research Center for Advanced Biomechanics, Kyushu University, Fukuoka, Japan Abstract Diamond like carbon (DLC) is one of the potential materials into orthopedics interfaces because of their super hardness, low friction, wear resistance, and biocompatibility. However, adhesion of DLC with substrate and bulge formation is a concern for the long durable tribological performances. In this study, total 8 types of DLC coatings were utilized which include 16 and 8 Bilayers of different combinations of carbon and doping materials. Roughness, wettability, hardness and modulus of elasticity were measure to define their surf...
Lubrication Science, 2014
Biological components of synovial fluid and their concentration play a crucial role in the lubric... more Biological components of synovial fluid and their concentration play a crucial role in the lubrication mechanism of artificial joints, particularly boundary lubrication. The purpose of this review was to summarise and critically analyse the lubrication mechanism and their tribological outcomes to artificial joints. Thirteen papers published between 01/01/2003 and 28/02/2013 met the inclusion criteria for the review. Four major biological components of synovial fluid (albumin, globulin, hyaluronic acid and lubricin) were found to have an influence on film thickness, friction coefficient and wear rate. The role of these components was reported to be varied, depending on not only their composition and concentration but also surface material properties, wettability, temperature and pressure. The findings suggest that an appropriate synovial fluid composition should be represented in a simulated body fluid in order to evaluate an implant material and subsequently to conduct biotribology tests.
In the world, approximately 800,000 total hip replacements are implanted, while, at least 50,000 ... more In the world, approximately 800,000 total hip replacements are implanted, while, at least 50,000 hip replacements are performed in the United Kingdom each year. Orthopaedic surgeons have traditionally delayed joint replacement surgery in patients younger than 60 due to its limited survivorship time and biological effect inside the human body. The highest percentage ͑71%͒ hip joint failure was caused by aseptic loosening of the femoral and acetabular components and the war rate and debris are the accepted causes of that aseptic loosening. The wear particles, either ion or stable form, can react with proteins and change the pH value of albumin solutions inside the human body, causing damage to the DNA resulting in genotoxicity. There has been a great deal of research into the materials, dimension of the prosthesis, surface roughness, and lubrication effect by surface coating. But it is very rare to apply surface texture technique to a metallic prosthesis bearing surface although it has proven very successful in many engineering applications including automobile industry due to secondary lubrication effect and hydrodynamic effect. A TE 77 high frequency friction simulator has been used for the experiment where specimens were manufactured with 50 mm diameters and 50 m clearance. A dynamic loading was applied synchronized with Hip CD 98 while the temperature was controlled at 37°C. The output data including friction coefficient, friction force and contact pot were recorded in connected computer via COM-PEND 2000 software. The surfaces were inspected after and before test under scanning electronic microscopy. The plateau honed surfaces were produced on the moving specimens with controlled load, speed and various grade of emery paper using a specially designed tool. The friction coefficient was recorded 0.035 for the honing surface which was made by 30 kg laod and 60 emery paper, 0.04 for the honing surface profile made by 30 kg load and 150 emery paper and 0.06 for plane surface after one million cycles. The rest of surfaces profiled surface were broken down before one million cycles. That made a conclusion that plateau honing surface made with 30 kg load and 60 emery paper was best surface texture profile ͑45°honed angle, 40Ϯ 10 m width and 35Ϯ 10 m depth honing͒ for the metal on metal hip prosthesis. The comparison experiment was continue for plane surface and plateau honing surface of 60 emery paper and 30 kg load up to one and half millions cycles. It was found that the friction coefficient ͑0.03͒ was further reduced 0.005 after one and half million cycles for plateau honing surface but it was increased nearly double ͑0.065͒ for plane surface. The static friction coefficient was also reduced 38% in case of that plateau honing surface. The contact pot profile which is an indicator of fluid film thickness was noticed higher in plateau honing surface. This was evidence that the lubrication distribution was better in plateau honed surface which should provide longer life of joint, reduce wear and improves acceptability of metal on metal hip joints.
The aim of the study was to investigate whether a modified ceramic head surface could reduce the ... more The aim of the study was to investigate whether a modified ceramic head surface could reduce the friction and wear rate of simulated ceramic-on-polyethylene hip joints. To address this aim, ultra-high molecular weight polyethylene (UHMWPE) was made to slide on aluminium oxide (Al 2 O 3 ), dimpled Al 2 O 3 , diamond-like carbon (DLC) coated and DLC-coated dimpled substrates. The experiment condition was replicated to simulate artificial hip joints in terms of contact pressure, speed and temperature. UHMWPE on non-dimpled Al 2 O 3 showed lower friction coefficient and wear rate compared to other advanced surfaces. Lower wettability, and higher hardness and surface adhesion of DLC resulted in increased friction and wear. The high difference in modulus of elasticity and hardness between UHMWPE and both, Al 2 O 3 and DLC, reduced the effectiveness of textured surface techniques in friction and wear reduction. Therefore, no tribological benefit was found by fabricating either DLC coating or surface texturing on hard surface when rubbed against softer UHMWPE.
The tribological outcomes of micro dent are found to be outstanding in many engineering and natur... more The tribological outcomes of micro dent are found to be outstanding in many engineering and natural surfaces. Ceramic (Al 2 O 3 ) is considered one of the most potential material to bearing surfaces particularly, artificial hip or knee implant. A well-defined micro dent on alumina oxide interface could further decrease friction and wear rate, thus increase their stability and durability. In this study we fabricated circular micro dent surface profiles (Dia: 400µm, Depth 20µm, P: 1.5mm; Dia: 400µm, Depth 20µm, P: 2mm) on pure Al 2 O 3 (99.6%) substrate by using a micro tool machines. A preliminary tribological experiment was carried out to compare friction coefficient of these fabricated dent surfaces with that of nontextured surfaces. The experiment was carried on well know pin-ondisk specimens while other experimental parameters such as hertz pressure, speed, lubrication, and temperature were maintained to standard of simulated hip joints condition. The experiment results revealed that micro dent surface texture reduced 15%, 8% and 4% friction coefficient under 0.132,0.162, 0.187 GPa contact pressure respectively. Since this is a preliminary tribological study, we will pursue further experiments considering higher ranges of dent profiles and longer run experiments. However, the preliminary results confirmed the suitability of fabricating dent profile to ceramic surfaces by using micro tooling, and also their improved tribological performance in simulated hip joints.
Tribology Online, 2013
Wear rate and debris are key problems to implanted metal-on-metal hip joints. Surface texture on ... more Wear rate and debris are key problems to implanted metal-on-metal hip joints. Surface texture on bearing surfaces is reported to increase tribological performances. Research on the translation of this technology to metal-on-metal hip joint for reduction of friction, wear rate and debris generation is limited. The aim of this study was to investigate, by theoretical predictions and experimental investigations, the tribological properties of simulated metal-on-metal hip joints with different surface textures. Three different honed surfaces were produced with emery paper at controlled load and speed. The experiments were carried out using a computer-controlled friction simulator. Theoretical prediction was carried out using an existing model for textured surfaces. Both experimental and theoretical results demonstrated that honed surfaces had lower friction coefficients during walking and stairs ascent and descent, demonstrating their potential use in metal on metal hip joints for increased implant longevity.
International Journal of Precision Engineering and Manufacturing, 2013
Surface texture technique increases the tribological capability and performance of bearing surfac... more Surface texture technique increases the tribological capability and performance of bearing surfaces. This technology has a number of applications, including car engines and golf balls. However, the use of texture surface in artificial hip joints has not been adequately explored. The aim of the study is to investigate the effects of plateau honed surfaces on the tribological performance of metal-on-metal hip joints. Four sets of different plateau honed surfaces and a set of non-textured surface were investigated on a friction simulator with a lubricant having similar viscosity of pseudo-synovial fluid. The results showed 50% and 38% reductions in static and dynamic friction coefficient, respectively, for a honed surface (honed surface 3) compared with those of a non-textured surface after 1 million cycles. There was a number of wear signs, including adhesive and fatigue wear in all of the experimental surfaces. Nevertheless, the wear signs in the honed surface 3 were minor. Lubrication film thickness was thicker, and third body abrasive wear assumed to reduce in the honed surface since wear debris removed through honed channel. Therefore, the performance of a well-designed plateau-honed surface is significant in tribological aspects of metal-on-metal hip joints.
PLoS ONE, 2014
Cricket has over the years gained much popularity in Asia, thus the number of cricket players has... more Cricket has over the years gained much popularity in Asia, thus the number of cricket players has also grown in tandem. However, cricket players are not as fortunate as other athletes as they do not always have a standard cricket infrastructure to practice; therefore, the injury prevalence is expected to be high. Unfortunately, very few studies have been conducted to investigate the nature and pattern of cricket injuries prevalent to cricketers in this region. Therefore, a prospective cohort injury surveillance study was conducted during the Asian Cricket Council (ACC) Under-19 Elite Cup held in June 2013 in order to gather more data on the type of injuries sustained by cricket players. Overall, 31 injuries occurred to 28 players throughout the tournament, of which 7 injuries happened during practice sessions. The overall injury incidence rate (IIR) was 292.0 per 10,000 player hours (95% CI 176.9-407.1) and 10.4 per 10,000 balls faced and 2.6 per 1000 overs bowled delivered during batting and bowling, respectively. Injuries to the lower limb (IIR: 146; 95% CI 1.8-98.2) were the most frequent, followed by injuries to the upper limb (97.3;95% CI 30.2-164.5) and to the trunk and back (IIR: 36.5;95% CI 0.0-77.7). Sprain/strains (IIR 109.5; to muscle/tendon and joint/ligament were the most commonly reported nature of injury. This is the first study investigating injury incidence among the players of the ACC. It provides an overview of injuries sustained by elite players' under-19 years of age from10 Asian countries. The overall IIR is similar to earlier studies conducted in well-established cricket playing nations.
IOP science, Feb 1, 2014
Coatings such as diamond-like carbon (DLC) and titanium nitride (TiN) are employed in joint impla... more Coatings such as diamond-like carbon (DLC) and titanium nitride (TiN) are employed in joint implants due to their excellent tribological properties. Recently, graphite-like carbon (GLC) and tantalum (Ta) have been proven to have good potential as coating as they possess mechanical properties similar to bones—high hardness and high flexibility. The purpose of this systematic literature review is to summarize the coating techniques of these four materials in order to compare their mechanical properties and tribological outcomes. Eighteen studies published between January 2000 and February 2013 have met the inclusion criteria for this review. Details of their fabrication parameters, material and mechanical properties along with the tribological outcomes, such as friction and wear rate, were identified and are presented in a systematic way. Although experiment conditions varied, we conclude that Ta has the lowest wear rate compared to DLC, GLC and TiN because it has a lower wear rate with high contact pressure as well as higher hardness to elasticity ratio. However, a further tribology test is needed in an environment which replicates artificial joints to confirm the acceptability of these findings.
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Papers by Dipankar Choudhury