Bacteria-related pathogenic diseases are one of the major health problems throughout the world. Salmonella is a genus of rod-shaped Gram-negative enterobacteria of which more than 2600 serotypes have been identified. Infection with Salmonella can cause salmonellosis, a serious bacterial toxi-infection syndrome associated with gastroenteritis, and paralyphoid and typhoid fevers. Its rapid and sensitive detection is a key to the prevention of problems related to health. This paper describes the development of antibody and DNA sensors for Salmonella detection using a microfluidic-based electrochemical system. Commercial Salmonella typhimurium and Salmonella typhimurium from human stool samples were investigated using standard and nanomaterial-amplified antibody sensors. S. typhimurium could be detected down to 1 cfu mL−1. The specificity of immunoassay was tested by studying with non-specific bacteria including E. coli and S. aureus that revealed only 2.01% and 2.66% binding when compared to the target bacterium. On the other hand, the quantification of Salmonella DNA was investigated in a concentration range of 0.002–200 µM using the developed DNA biosensor that demonstrated very high specificity and sensitivity with a detection limit of 0.94 nM. Our custom-designed microfluidic sensor offers rapid, highly sensitive, and specific diagnostic assay approaches for pathogen detection.
Stabilization after the lithography process is crucial in order to prevent deformation of photoresist patterns by other thermal processes used in semiconductor production. UV hardening is capable of minimizing negative effects of thermal processes such as rounded shaped lines; line width widening or shrinkage and CD shift. The amount of UV energy absorbed and final process temperature are important process parameters; which effect directly the degree of cross-linking. So, this paper examines optimization of process parameters such as the ramp rate, which is the tangent of the temperature-time curve (°C/sec) and the final temperature. Also the ramp rate indicates the time; that wafer is exposed to the high degree of UV energy. Process parameters are optimised with respect to the improvement of etch selectivity, decrease of the CD shift. Profile photos have been taken with Scanning Electron Microscope. In the experiments, the novolak based i-line photoresist and ICON-7 as anti reflecting coating are used for the lithography process. Many variables have been taken into consideration while determining optimum process parameters. These are resist thickness, type of the surface layer of wafer, magnitude of the critical dimension (>1 μm & < 1 μm ) and the size of the open area on the reticle used during exposure.
As the development of the ULSI technique with respect to the decrease in the feature sizes, critical dimension has become a vital parameter for the IC manufacturing. For sub-micron technologies, there has always been a significant mismatch between the layout and post lithography patterns. Since most of the conventional optimization techniques are model based, it is quite hard to obtain a good accuracy for a real-world solution. Moreover, these methods can not easily be integrated to any fabrication environment. This paper presents a layout correction technique which uses a look-up table of measured patterns with 0.3um and 0.4um critical dimensions. An interpolation method that takes the design grids into account has been used to obtain the optimum layout for sub-micron ULSI circuits. This paper not only focuses on an experimental and accurate critical dimension optimization, but also draws attention how to implement this methodology for any fabrication environment.
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