Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Polymer nanocomposite nanomechanical cantilever sensors: material characterization, device development and application in explosive vapour detection

Abstract: This paper reports an optimized and highly sensitive piezoresistive SU-8 nanocomposite microcantilever sensor and its application for detection of explosives in vapour phase. The optimization has been in improving its electrical, mechanical and transduction characteristics. We have achieved a better dispersion of carbon black (CB) in the SU-8/CB nanocomposite piezoresistor and arrived at an optimal range of 8?9?vol% CB concentration by performing a systematic mechanical and electrical characterization of polymer nanocomposites. Mechanical characterization of SU-8/CB nanocomposite thin films was performed using the nanoindentation technique with an appropriate substrate effect analysis. Piezoresistive microcantilevers having an optimum carbon black concentration were fabricated using a design aimed at surface stress measurements with reduced fabrication process complexity. The optimal range of 8?9?vol% CB concentration has resulted in an improved sensitivity, low device variability and low noise level. The resonant frequency and spring constant of the microcantilever were found to be 22?kHz and 0.4? N?m ? 1 respectively. The devices exhibited a surface stress sensitivity of 7.6?ppm (mN?m ? 1) ? 1 and the noise characterization results support their suitability for biochemical sensing applications. This paper also reports the ability of the sensor in detecting TNT vapour concentration down to less than six parts per billion with a sensitivity of 1? mV/ppb.

Self-Aggregation and Assembly of Size-Tunable Transition Metal Doped ZnO Nanocrystals

Abstract: Size tunable transition metal (Mn, Ni) doped ZnO nanocrystals have been synthesized through a soft chemical route. These nanocrystals self-aggregated themselves in a highly mesoporous spherical superstructure of broad size distribution. The formation of nanocrystals and porous spherical superstructures can be understood as a result of a combination of factors such as the presence of negatively charged carboxylate ions, van der Waals force, the polar nature of ZnO crystal surfaces, and oriented attachment. Monodispersed porous spheres were obtained by size selective separation and then assembled into a face-centered cubic (FCC) close packed superstructure with its (111) plane oriented parallel to the sample surface. The assembled structures exhibit the presence of the photonic stop band in the (111) direction, and the nanocrystals display ferromagnetic like behavior presumably due to defects.