Papers by Keyword: Nanotopography

Abstract: In recent study, vertically aligned TiO₂ nanotubes have become the primary candidates that can provide direct control of many type cell behaviors and its functionality. TiO₂ nanotubes were successfully developed within 10 V to 40 V of applied potential. The intensity of peaks (101) increases with increasing voltage up to 40 V, indicating an improvement in degree of crystalinity. The average crystallite size of the samples anodized at 10 V is about 19.65 nm and increase to 30.88 nm at 40 V. PA6 cell interaction were high on 40 V sample (110 nm-diameter) TiO₂ nanotubes . It was found that anatase phase with appropriate diameter are believed to affect the growth of cells.

Abstract: Form accuracy and smooth surface is required in precision grinding. And the form accuracy and surface roughness are improved year by year. However, the more the surface roughness becomes smooth, the more the grinding marks become remarkable. The grinding mark deteriorates the uniformity of ground surface. In this study, relationship between the uniformity of non-axisymmetric aspherical ground surface and grinding condition is analyzed theoretically. As a result, it is found that there are optimum grinding conditions.

Abstract: Leading edge lithography processes require silicon wafers of nearly perfect flatness. In order to improve wafer manufacturing processes as well as the wafer quality, already early manufacturing processes like grinding and lapping have to be monitored. Assessment of nanotopography (NT) is an established approach to analyze surface features in a spatial wavelength range of 0.2 to 20 mm on silicon wafers end of line. This paper presents a fully automated measurement tool to measure NT on wafers with low reflectivity and wafer sizes up to 300 mm, based on the FRT MicroProf^® MFE series. The system features a newly developed white-light interferometry sensor with a field of view of approximately 85 x 85 mm². 16 single measurements are stitched to cover the entire surface of a 300 mm wafer. An NT analysis optimized stitching algorithm was developed in order to combine the individual images to a complete wafer map. The stitched map of the non-polished wafer is subsequently high-pass filtered and analyzed to quantify NT. Measurement system analysis studies provided repeatability values below 1 nm at a throughput of > 20 wafer/h.

Abstract: When used as an implanted material, titanium (Ti) surface controls the subsequent biological reactions and leads to tissue integration. Cells interactions with the surface, through a protein layer that is being formed from the moment Ti surface comes in contact with blood and its components, and indeed this protein layer formation, are regulated by surface properties such as topography, chemistry, charge and surface energy. Currently, the implementation of nanotechnology, in an attempt to support mimicking the natural features of extracellular matrix, has provided novel approaches for understanding and translating surface mechanisms whose modification and tailoring are expected to lead to enhanced cell activity and improved integration. Despite the fact that there has been extensive research on this subject, the sequence of interactions that take place instantly after the exposure of the implanted material into the biologic microenvironment are not well documented and need further investigation as well as the optimization of characteristics of Ti surface. This review, including theoretical and experimental studies, summarizes some of the latest advances on the Ti surface concerning modifications on surface properties and how these modifications affect biomolecular reactions and also attempts to present the initial adsorption mechanism of water and protein molecules to the surface.

Abstract: This manuscript reviews about titanium surface modification techniques for its application in orthopaedic and dental implants. There are a few limitations in the long term prognosis of orthopaedic and dental implants. Poor osseointegration with bone, periimplant infection leading to implant failure and short term longevity demanding revision surgery, are to mention a few. Micro- and nanoscale modification of titanium surface using physicochemical, morphological and biochemical approaches have resulted in higher bone to implant contact ratio and improved osseointegration. With recent advances in micro, nano-fabrication techniques and multidisciplinary research studies focusing on bridging biomaterials for medical applications, TiO2 nanotubes have been extensively studied for implant applications. The need for titanium implant surface that can closely mimic the nanoscale architecture of human bone has become a priority. For such purpose, TiO2 nanotubes of different dimensions and architectural fashions at the nanoscale level are being evaluated. This manuscript discusses in brief about the in-vitro and in-vivo studies on titanium surface modification techniques. This manuscript also addresses the recent studies done on such nanotubular surfaces for the effective delivery of osteoinductive growth factors and anti bacterial/ anti inflammatory drugs to promote osseointegration and prevent peri-implant infection.

Abstract: Warp accuracy and nanotopography in the silicon wafer slicing process influence the final quality of the wafer. Therefore, methods to improve these factors are important. And this will require the achievement of low costs and high quality processing – conflicting requirements – with larger sized wafers than in previous generations. The present study was performed to assess mechanical factors, such as machine static accuracy and thermal deformation, to improve the accuracy of multi-wire saws. This report deals with the influence of thermal deformation of the ingot and wire guides upon processing accuracy, and describes the assessment results.

Abstract: The use of aspherical optical parts has become common as optical instruments are becoming smaller with and are achieving higher resolution. Nano-order roughness and high-precision shapes are simultaneously required for the surface of aspherical optical parts. At present, form accuracy of the aspherical lens becomes less than 50 nm, and the maximum height roughness becomes less than 20 nm. These values of form accuracy and maximum height roughness satisfy the requirement for most precision optical parts. However, nano-topography, which causes grinding marks and deteriorates accuracy of optical parts, is generated on the ground surface. Conventional evaluation criteria such as form accuracy and surface roughness cannot estimate the nano-topography. In the present paper, the cross sectional profile of the axisymmetric ground surface is calculated in order to estimate the distribution of the nano-topography. As a result, the possibility of control of the nano-topography distribution is confirmed. In addition, controlling the amplitude of nano-topography is easier than controlling the distribution of nano-topography.