Defence Materials and Stores R and D Establishment DRDO

Kānpur, India

Defence Materials and Stores R and D Establishment DRDO

Kānpur, India
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Srivastava A.K.,Defence Materials and Stores R and D Establishment DRDO | Srivastava A.K.,Indian Institute of Technology Kanpur | Sachan P.,Indian Institute of Technology Kanpur | Samanta C.,Indian Institute of Technology Kanpur | And 2 more authors.
Applied Surface Science | Year: 2014

We explore self-organized dewetting of ultrathin films of a novel metal complex as a one step surface patterning method to create nanoislands of iron, using which spatially separated carbon nanostructures were synthesized. Dewetting of ultrathin metal complex films was induced by two different methods: liquid solvent exposure and thermal annealing to engender surface patterning. For thermal dewetting, thin films of the iron oleate complex were dewetted at high temperature. In the case of liquid solvent assisted dewetting, the metal complex, mixed with a sacrificial polymer (polystyrene) was spin coated as thin films (<40 nm) and then dewetted under an optimal solution mixture consisting of methyl ethyl ketone, acetone and water. The carrier polymer was then selectively removed to produce the iron metal islands. These metal islands were used for selective growth of discrete patches of multiwall CNTs and CNFs by a chemical vapor deposition (CVD) process. Solvent induced dewetting showed clear advantages over thermal dewetting owing to reduced size of catalyst domains formed by dewetting, an improved control over CNT growth as well as in its ability to immobilize the seed particles. The generic solution mediated dewetting and pattern generation in thin films of various catalytic precursors can thus be a powerful method for selective domain growth of a variety of functional nanomaterials. © 2013 Elsevier B.V. All rights reserved.


Srivastava A.K.,Defence Materials and Stores R and D Establishment DRDO | Srivastava A.K.,Indian Institute of Technology Kanpur | Bhartia B.,Indian Institute of Technology Kanpur | Mukhopadhyay K.,Defence Materials and Stores R and D Establishment DRDO | Sharma A.,Indian Institute of Technology Kanpur
Sensors and Actuators, A: Physical | Year: 2015

We report a novel approach for the fabrication of a user friendly functional device with dry electrodes for the measurement of biopotentials (electrocardiograph or ECG, electroencephalogram or EEG) that allows extended measurement time, reduced preparation time and less motion induced artifacts compared to wet gel based commercial electrodes. The dry micro-electrode arrays were fabricated by the UV maskless lithography in the grayscale or back-exposure modes using a biocompatible polymer SU-8. This produced conical shaped, mechanically robust micro-needles on a flexible polymer substrate which conforms to the body contours thereby greatly reducing the motion artifacts. The device was tested in vivo on human subjects and compared with the currently utilized wet gel based Ag/AgCl electrodes. It demonstrated comparable performance in capturing ECG and EEG signals. The electrodes were tested for long duration (48 h) without any signs of degradation. This device can be utilized for long term as well as remote health monitoring of the subjects. © 2015 Elsevier B.V. All rights reserved.

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