Department of Physics
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Item Sensing of contaminants in potable water using TiO2 functional film(AIP, 2016-04) Manjuladevi, V.; Gupta, Rajiv; Gupta, Raj KumarThe piezoelectric based quartz crystal microbalance is employed for sensing contaminants in potable water. A spin coated thin layer of TiO2 nanoparticles was formed at the sensing area of a 5 MHz AT-cut quartz wafer. The thin film of TiO2 nanoparticles forms a mesoporous functional layer for the trapping of water borne contaminants. The morphology of the thin film of TiO2 nanoparticles was studied using field emission scanning electron microscope (FESEM). The surface morphology of the TiO2 nanoparticles reveals the mesoporous structures indicating large number of defects and porous sites. Such film was employed for the detection of water borne contaminants by detecting the piezoelectric response from a quartz crystal microbalance. We found the film to be very sensitive to the contaminants. The minimum detection limit was found to be 330 ppb. The effect of surface recharging was also studied by altering the physical conditions so that the film can be used for repetitive usage.Item Detection of cadmium ion in water using films of nanocomposite of functionalized carbon nanotubes and anionic polymer(AIP, 2018-05) Manjuladevi, V.; Gupta, Raj KumarPresence of cadmium in drinking water is one of the major threats to human health. According to international standards, the maximum permission concentration of cadmium ion in drinking water should be less than 0.002 to 0.010mg/l (2-10 ppb). It is one of the major contaminants in potable water in western part of Indian subcontinent. It is found up to 2.3 to 8.6 mg/l in Rajasthan water. In this article, we report our study on detection of cadmium ion in water employing a sensing layer of nanocomposites of functionalized single walled carbon nanotubes (SWCNTs) and polyacrylic acid (PAA). The film was deposited onto 5 MHz AT-cut quartz crystal of a quartz crystal microbalance (QCM). The response was collected in both static and dynamic mode. We obtained a linear response curve in a given concentration range of cadmium ion indicating the suitability of the functional layer for cadmium ion detection in water. The surface morphology of the functional layer was studied using atomic force microscope before and after sensing.Item Interaction of bovine serum albumin protein with self assembled monolayer of mercaptoundecanoic acid(AIP, 2016-05) Manjuladevi, V.; Gupta, Raj KumarDetection of proteins and other biomolecules in liquid phase is the essence for the design of a biosensor. The sensitivity of a sensor can be enhanced by the appropriate functionalization of the sensing area so as to establish the molecular specific interaction. In the present work, we have studied the interaction of bovine serum albumin (BSA) protein with a chemically functionalized surface using a quartz crystal microbalance (QCM). The gold-coated quartz crystals (AT-cut/5 MHz) were functionalized by forming self-assembled monolayer (SAM) of 11-Mercaptoundecanoic acid (MUA). The adsorption characteristics of BSA onto SAM of MUA on quartz crystal are reported. BSA showed the highest affinity for SAM of MUA as compared to pure gold surface. The SAM of MUA provides carboxylated surface which enhances not only the adsorption of the BSA protein but also a very stable BSA-MUA complex in the liquid phase.