Naga Siva Gunda | University of Alberta (original) (raw)

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Papers by Naga Siva Gunda

Research paper thumbnail of Design of an Arsine Gas Free Rapid Arsenic Detector Using a Novel Luminescent Metal-Organic Framework

Research paper thumbnail of Effect of scanning resolution and fluence fluctuation on femtosecond laser ablation of thin films

Applied Physics A: Materials Science & Processing, 2003

Femtosecond-pulse laser pulses have been shown to hold great potential for high-precision microma... more Femtosecond-pulse laser pulses have been shown to hold great potential for high-precision micromachining. Much research has been done to characterize the laser parameters for predicting the feature size, and the most important of these is the number of pulses incident at each point of ablation. Theoretical modeling, so far, has been restricted to a single point where the number of

Research paper thumbnail of Development of Rapid Techniques for Healthcare and Environment Monitoring

Research paper thumbnail of Simultaneous Dropwise and Filmwise Condensation on a Microstructured Surface without the Assistance of a Hydrophobic Coating

Abstract While wicking or spreading of a liquid through microstructures has been found to be prom... more Abstract While wicking or spreading of a liquid through microstructures has been found to be promising for applications such as textiles, microelectronics or heat sinks, the effects of such structured surfaces on condensation phase change has received less attention. On a hydrophilic surface and for a fixed micropillar aspect ratio (height/diameter), the spacing between pillars is found to have a strong impact on the dynamics of condensation and on the final morphology of the condensate. In the case of micropillars with a large spacing between pillars, the condensate grows initially dropwise, and thereafter, as condensation develops, the condensate overcomes the pillars’ height flooding the substrate, and condensation continuous in a filmwise condensation (FWC) fashion. In contrast, filmwise condensation and the continuous nucleation, growth, and departure of drops at the pillars’ tops in a dropwise condensation (DWC) fashion occurs when the spacing between pillars is decreased. In this configuration, the geometry of the microstructures constrains the condensate between the pillars and rise of the condensate interface above the micropillars’ height is not thermodynamically favorable, while the top of the pillars act as nucleation sites. We refer to this latter condensation behavior as simultaneous dropwise/filmwise condensation. These observations were enabled by the excellent spatial and temporal resolution of Environmental Scanning Electron Microscopy. A heat transfer model is proposed to demonstrate the greater heat transfer performance of the simultaneous dropwise/filmwise condensation behavior on these surfaces when compared to solely filmwise condensation. The enhanced heat transfer is realizable due to the ability to maintain a thin film within the microstructures and to the active dropwise condensation at the micropillars’ tops. We report for the first time the occurrence of dropwise condensation on a completely hydrophilic wettability configuration without the assistance of a hydrophobic coating. Our findings pave the way to the development of microstructures for enhanced condensation heat transfer.

Research paper thumbnail of Is micro-nano texture the only reason for under-water superoleophobicity of fish scale?

Research paper thumbnail of Electrochemical Detection of Cardiac Myoglobin Using Microchannel with Interdigitated Electrodes (MCIE)

ECS Meeting Abstracts

The present study aims to solve a problem that runs rampant across North America i.e. heart attac... more The present study aims to solve a problem that runs rampant across North America i.e. heart attacks. Each year approximately 70,000 heart attacks occur in Canada. That means one heart attack every 7 minutes and costs the Canadian economy $20.9 billion each year 1. In 2010-2011, there were approximately ~300,000 hospitalizations due to heart diseases 1. This number is increasing at an alarming rate due to many reasons of life style. Most of the deaths reported are due to the lack of prior diagnosis of heart damage. Figure 1: (Top) Picture of microchannel with interdigitated electrode (MCIE) and optical images of two different electrode configurations; (Bottom) Schematic showing the MCIE with immunoassay on interdigitated electrodes (not to scale).

Research paper thumbnail of Rapid Detection of Total Coliform and E.Coli in Contaminated Water Using Chemically Modified Microwells

Research paper thumbnail of Distinguished Invited Speaker--Capillary-Based Assay for Cardiac Markers With Cantilever Platform

Research paper thumbnail of Mobile Water Kit 2.0: A Field Deployable Solution for E. coli Detection in Potable Water

Research paper thumbnail of Development of Dual-Phobic Surfaces: Superamphiphobicity in Air and Oleophobicity Underwater

ACS Sustainable Chemistry & Engineering

In the present work, we describe a simple method to fabricate dual-phobic fluorosilane-coated pol... more In the present work, we describe a simple method to fabricate dual-phobic fluorosilane-coated polydimethylsiloxane/camphor-soot/polydimethylsiloxane (FPCP) composite surfaces. The surface morphology and silane treatment provide the needed texture on the FPCP composite surface to demonstrate superamphiphobicity in the air and oleophobicity in the underwater environment. High-resolution field emission-scanning electron microscopy (FESEM) imaging of the FPCP composite surface illustrates the top surface with an array of hollow cylindrical pillars. The dimensions of surface texture are measured, and the relationship between the wetting states of liquid and textures surface in the air as well as in an underwater environment is studied. Also, X-ray photoelectron spectroscopy (XPS) analysis demonstrates different changes of plain polydimethylsiloxane (PDMS), PDMS/camphor-soot/PDMS (PCP), and fluorosilane-coated PCP (FPCP) composite surfaces that are responsible for diverse wettability properties. We compared the...

Research paper thumbnail of Rapid Water Quality Monitoring for Microbial Contamination

The Electrochemical Society Interface

Research paper thumbnail of Simultaneous dropwise and filmwise condensation on hydrophilic microstructured surfaces

International Journal of Heat and Mass Transfer

Abstract While wicking or spreading of a liquid through microstructures has been found to be prom... more Abstract While wicking or spreading of a liquid through microstructures has been found to be promising for applications such as textiles, microelectronics or heat sinks, the effects of such structured surfaces on condensation phase change has received less attention. On a hydrophilic surface and for a fixed micropillar aspect ratio (height/diameter), the spacing between pillars is found to have a strong impact on the dynamics of condensation and on the final morphology of the condensate. In the case of micropillars with a large spacing between pillars, the condensate grows initially dropwise, and thereafter, as condensation develops, the condensate overcomes the pillars’ height flooding the substrate, and condensation continuous in a filmwise condensation (FWC) fashion. In contrast, filmwise condensation and the continuous nucleation, growth, and departure of drops at the pillars’ tops in a dropwise condensation (DWC) fashion occurs when the spacing between pillars is decreased. In this configuration, the geometry of the microstructures constrains the condensate between the pillars and rise of the condensate interface above the micropillars’ height is not thermodynamically favorable, while the top of the pillars act as nucleation sites. We refer to this latter condensation behavior as simultaneous dropwise/filmwise condensation. These observations were enabled by the excellent spatial and temporal resolution of Environmental Scanning Electron Microscopy. A heat transfer model is proposed to demonstrate the greater heat transfer performance of the simultaneous dropwise/filmwise condensation behavior on these surfaces when compared to solely filmwise condensation. The enhanced heat transfer is realizable due to the ability to maintain a thin film within the microstructures and to the active dropwise condensation at the micropillars’ tops. We report for the first time the occurrence of dropwise condensation on a completely hydrophilic wettability configuration without the assistance of a hydrophobic coating. Our findings pave the way to the development of microstructures for enhanced condensation heat transfer.

Research paper thumbnail of DipTest: A litmus test for E. coli detection in water

PLOS ONE

We have developed a new litmus paper test (DipTest) for detecting Escherichia coli (E. coli) in w... more We have developed a new litmus paper test (DipTest) for detecting Escherichia coli (E. coli) in water samples by performing enzymatic reactions directly on the porous paper substrate. The paper strip consists of a long narrow piece of cellulose blotting paper coated with chemoattractant (at bottom edge), wax hydrophobic barrier (at the top edge), and custom formulated chemical reagents (at reaction zone immediately below the wax hydrophobic barrier). When the paper strip is dipped in water, E. coli in the water sample is attracted toward the paper strip due to a chemotaxic mechanism followed by the ascent along the paper strip toward the reaction zone due to a capillary wicking mechanism, and finally the capillary motion is arrested at the top edge of the paper strip by the hydrophobic barrier. The E. coli concentrated at the reaction zone of the paper strip will react with custom formulated chemical reagents to produce a pinkish-red color. Such a color change on the paper strip when dipped into water samples indicates the presence of E. coli contamination in potable water. The performance of the DipTest device has been checked with different known concentrations of E. coli contaminated water samples using different dip and wait times. The DipTest device has also been tested with different interfering bacteria and chemical contaminants. It has been observed that the different interfering contaminants do not have any impact on the DipTest, and it can become a potential solution for screening water samples for E. coli contamination at the point of source.

Research paper thumbnail of Wetting characteristics of underwater micro-patterned surfaces

RSC Adv., 2017

Wetting phenomena of underwater systems do not always follow the classical Wenzel and Cassie–Baxt... more Wetting phenomena of underwater systems do not always follow the classical Wenzel and Cassie–Baxter configurations.

Research paper thumbnail of Underwater Wetting Behavior on Micro-Patterned Surfaces

ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels, 2016

An experimental study has been presented to validate the applicability of Wenzel and Cassie-Baxte... more An experimental study has been presented to validate the applicability of Wenzel and Cassie-Baxter theories for wetting of textured surfaces placed under-water. Silicon based micro-patterned substrates are fabricated and careful experimental investigation has been performed to study the wetting signature of oil drops on these substrates when placed under-water. On analysis of relevant experimental data (macroscopic advancing, equilibrium and receding contact angles), it has been found that they are inconsistent with the Wenzel and Cassie-Baxter wetting theories.Copyright © 2016 by ASME

Research paper thumbnail of Droplet migration during condensation on chemically patterned micropillars

RSC Adv., 2016

Droplet migration from a micropillar's side to its top due to the wettability gradient impose... more Droplet migration from a micropillar's side to its top due to the wettability gradient imposed by our novel fabrication process.

Research paper thumbnail of A hydrogel based rapid test method for detection of Escherichia coli (E. coli) in contaminated water samples

The Analyst, 2016

We have formulated a new chemical composition for rapid detection of Escherichia coli (E. coli) w... more We have formulated a new chemical composition for rapid detection of Escherichia coli (E. coli) with currently available enzymatic substrates.

Research paper thumbnail of Evaluation of the antimicrobial activity of Moringa oleifera seed extract as a sustainable solution for potable water

RSC Adv., 2016

We have provided a detailed antimicrobial study of the seed extract ofMoringa oleifera, a common ... more We have provided a detailed antimicrobial study of the seed extract ofMoringa oleifera, a common medicinal plant.

Research paper thumbnail of Hollow fiber concentrator for water quality monitoring: role of surfactant based elution fluids

RSC Adv., 2015

Simple and efficient concentrators are indispensable to the development of portable biosensor bas... more Simple and efficient concentrators are indispensable to the development of portable biosensor based detection platforms for the determination of microbial contamination in water.

Research paper thumbnail of Needle-free drop deposition: Role of elastic membranes

RSC Adv., 2015

Needle-free contact angle measurement of low-energy surfaces (superhydrophobic, superoleophobic, ... more Needle-free contact angle measurement of low-energy surfaces (superhydrophobic, superoleophobic, etc.) is critical for characterizing such substrates.

Research paper thumbnail of Design of an Arsine Gas Free Rapid Arsenic Detector Using a Novel Luminescent Metal-Organic Framework

Research paper thumbnail of Effect of scanning resolution and fluence fluctuation on femtosecond laser ablation of thin films

Applied Physics A: Materials Science & Processing, 2003

Femtosecond-pulse laser pulses have been shown to hold great potential for high-precision microma... more Femtosecond-pulse laser pulses have been shown to hold great potential for high-precision micromachining. Much research has been done to characterize the laser parameters for predicting the feature size, and the most important of these is the number of pulses incident at each point of ablation. Theoretical modeling, so far, has been restricted to a single point where the number of

Research paper thumbnail of Development of Rapid Techniques for Healthcare and Environment Monitoring

Research paper thumbnail of Simultaneous Dropwise and Filmwise Condensation on a Microstructured Surface without the Assistance of a Hydrophobic Coating

Abstract While wicking or spreading of a liquid through microstructures has been found to be prom... more Abstract While wicking or spreading of a liquid through microstructures has been found to be promising for applications such as textiles, microelectronics or heat sinks, the effects of such structured surfaces on condensation phase change has received less attention. On a hydrophilic surface and for a fixed micropillar aspect ratio (height/diameter), the spacing between pillars is found to have a strong impact on the dynamics of condensation and on the final morphology of the condensate. In the case of micropillars with a large spacing between pillars, the condensate grows initially dropwise, and thereafter, as condensation develops, the condensate overcomes the pillars’ height flooding the substrate, and condensation continuous in a filmwise condensation (FWC) fashion. In contrast, filmwise condensation and the continuous nucleation, growth, and departure of drops at the pillars’ tops in a dropwise condensation (DWC) fashion occurs when the spacing between pillars is decreased. In this configuration, the geometry of the microstructures constrains the condensate between the pillars and rise of the condensate interface above the micropillars’ height is not thermodynamically favorable, while the top of the pillars act as nucleation sites. We refer to this latter condensation behavior as simultaneous dropwise/filmwise condensation. These observations were enabled by the excellent spatial and temporal resolution of Environmental Scanning Electron Microscopy. A heat transfer model is proposed to demonstrate the greater heat transfer performance of the simultaneous dropwise/filmwise condensation behavior on these surfaces when compared to solely filmwise condensation. The enhanced heat transfer is realizable due to the ability to maintain a thin film within the microstructures and to the active dropwise condensation at the micropillars’ tops. We report for the first time the occurrence of dropwise condensation on a completely hydrophilic wettability configuration without the assistance of a hydrophobic coating. Our findings pave the way to the development of microstructures for enhanced condensation heat transfer.

Research paper thumbnail of Is micro-nano texture the only reason for under-water superoleophobicity of fish scale?

Research paper thumbnail of Electrochemical Detection of Cardiac Myoglobin Using Microchannel with Interdigitated Electrodes (MCIE)

ECS Meeting Abstracts

The present study aims to solve a problem that runs rampant across North America i.e. heart attac... more The present study aims to solve a problem that runs rampant across North America i.e. heart attacks. Each year approximately 70,000 heart attacks occur in Canada. That means one heart attack every 7 minutes and costs the Canadian economy $20.9 billion each year 1. In 2010-2011, there were approximately ~300,000 hospitalizations due to heart diseases 1. This number is increasing at an alarming rate due to many reasons of life style. Most of the deaths reported are due to the lack of prior diagnosis of heart damage. Figure 1: (Top) Picture of microchannel with interdigitated electrode (MCIE) and optical images of two different electrode configurations; (Bottom) Schematic showing the MCIE with immunoassay on interdigitated electrodes (not to scale).

Research paper thumbnail of Rapid Detection of Total Coliform and E.Coli in Contaminated Water Using Chemically Modified Microwells

Research paper thumbnail of Distinguished Invited Speaker--Capillary-Based Assay for Cardiac Markers With Cantilever Platform

Research paper thumbnail of Mobile Water Kit 2.0: A Field Deployable Solution for E. coli Detection in Potable Water

Research paper thumbnail of Development of Dual-Phobic Surfaces: Superamphiphobicity in Air and Oleophobicity Underwater

ACS Sustainable Chemistry & Engineering

In the present work, we describe a simple method to fabricate dual-phobic fluorosilane-coated pol... more In the present work, we describe a simple method to fabricate dual-phobic fluorosilane-coated polydimethylsiloxane/camphor-soot/polydimethylsiloxane (FPCP) composite surfaces. The surface morphology and silane treatment provide the needed texture on the FPCP composite surface to demonstrate superamphiphobicity in the air and oleophobicity in the underwater environment. High-resolution field emission-scanning electron microscopy (FESEM) imaging of the FPCP composite surface illustrates the top surface with an array of hollow cylindrical pillars. The dimensions of surface texture are measured, and the relationship between the wetting states of liquid and textures surface in the air as well as in an underwater environment is studied. Also, X-ray photoelectron spectroscopy (XPS) analysis demonstrates different changes of plain polydimethylsiloxane (PDMS), PDMS/camphor-soot/PDMS (PCP), and fluorosilane-coated PCP (FPCP) composite surfaces that are responsible for diverse wettability properties. We compared the...

Research paper thumbnail of Rapid Water Quality Monitoring for Microbial Contamination

The Electrochemical Society Interface

Research paper thumbnail of Simultaneous dropwise and filmwise condensation on hydrophilic microstructured surfaces

International Journal of Heat and Mass Transfer

Abstract While wicking or spreading of a liquid through microstructures has been found to be prom... more Abstract While wicking or spreading of a liquid through microstructures has been found to be promising for applications such as textiles, microelectronics or heat sinks, the effects of such structured surfaces on condensation phase change has received less attention. On a hydrophilic surface and for a fixed micropillar aspect ratio (height/diameter), the spacing between pillars is found to have a strong impact on the dynamics of condensation and on the final morphology of the condensate. In the case of micropillars with a large spacing between pillars, the condensate grows initially dropwise, and thereafter, as condensation develops, the condensate overcomes the pillars’ height flooding the substrate, and condensation continuous in a filmwise condensation (FWC) fashion. In contrast, filmwise condensation and the continuous nucleation, growth, and departure of drops at the pillars’ tops in a dropwise condensation (DWC) fashion occurs when the spacing between pillars is decreased. In this configuration, the geometry of the microstructures constrains the condensate between the pillars and rise of the condensate interface above the micropillars’ height is not thermodynamically favorable, while the top of the pillars act as nucleation sites. We refer to this latter condensation behavior as simultaneous dropwise/filmwise condensation. These observations were enabled by the excellent spatial and temporal resolution of Environmental Scanning Electron Microscopy. A heat transfer model is proposed to demonstrate the greater heat transfer performance of the simultaneous dropwise/filmwise condensation behavior on these surfaces when compared to solely filmwise condensation. The enhanced heat transfer is realizable due to the ability to maintain a thin film within the microstructures and to the active dropwise condensation at the micropillars’ tops. We report for the first time the occurrence of dropwise condensation on a completely hydrophilic wettability configuration without the assistance of a hydrophobic coating. Our findings pave the way to the development of microstructures for enhanced condensation heat transfer.

Research paper thumbnail of DipTest: A litmus test for E. coli detection in water

PLOS ONE

We have developed a new litmus paper test (DipTest) for detecting Escherichia coli (E. coli) in w... more We have developed a new litmus paper test (DipTest) for detecting Escherichia coli (E. coli) in water samples by performing enzymatic reactions directly on the porous paper substrate. The paper strip consists of a long narrow piece of cellulose blotting paper coated with chemoattractant (at bottom edge), wax hydrophobic barrier (at the top edge), and custom formulated chemical reagents (at reaction zone immediately below the wax hydrophobic barrier). When the paper strip is dipped in water, E. coli in the water sample is attracted toward the paper strip due to a chemotaxic mechanism followed by the ascent along the paper strip toward the reaction zone due to a capillary wicking mechanism, and finally the capillary motion is arrested at the top edge of the paper strip by the hydrophobic barrier. The E. coli concentrated at the reaction zone of the paper strip will react with custom formulated chemical reagents to produce a pinkish-red color. Such a color change on the paper strip when dipped into water samples indicates the presence of E. coli contamination in potable water. The performance of the DipTest device has been checked with different known concentrations of E. coli contaminated water samples using different dip and wait times. The DipTest device has also been tested with different interfering bacteria and chemical contaminants. It has been observed that the different interfering contaminants do not have any impact on the DipTest, and it can become a potential solution for screening water samples for E. coli contamination at the point of source.

Research paper thumbnail of Wetting characteristics of underwater micro-patterned surfaces

RSC Adv., 2017

Wetting phenomena of underwater systems do not always follow the classical Wenzel and Cassie–Baxt... more Wetting phenomena of underwater systems do not always follow the classical Wenzel and Cassie–Baxter configurations.

Research paper thumbnail of Underwater Wetting Behavior on Micro-Patterned Surfaces

ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels, 2016

An experimental study has been presented to validate the applicability of Wenzel and Cassie-Baxte... more An experimental study has been presented to validate the applicability of Wenzel and Cassie-Baxter theories for wetting of textured surfaces placed under-water. Silicon based micro-patterned substrates are fabricated and careful experimental investigation has been performed to study the wetting signature of oil drops on these substrates when placed under-water. On analysis of relevant experimental data (macroscopic advancing, equilibrium and receding contact angles), it has been found that they are inconsistent with the Wenzel and Cassie-Baxter wetting theories.Copyright © 2016 by ASME

Research paper thumbnail of Droplet migration during condensation on chemically patterned micropillars

RSC Adv., 2016

Droplet migration from a micropillar's side to its top due to the wettability gradient impose... more Droplet migration from a micropillar's side to its top due to the wettability gradient imposed by our novel fabrication process.

Research paper thumbnail of A hydrogel based rapid test method for detection of Escherichia coli (E. coli) in contaminated water samples

The Analyst, 2016

We have formulated a new chemical composition for rapid detection of Escherichia coli (E. coli) w... more We have formulated a new chemical composition for rapid detection of Escherichia coli (E. coli) with currently available enzymatic substrates.

Research paper thumbnail of Evaluation of the antimicrobial activity of Moringa oleifera seed extract as a sustainable solution for potable water

RSC Adv., 2016

We have provided a detailed antimicrobial study of the seed extract ofMoringa oleifera, a common ... more We have provided a detailed antimicrobial study of the seed extract ofMoringa oleifera, a common medicinal plant.

Research paper thumbnail of Hollow fiber concentrator for water quality monitoring: role of surfactant based elution fluids

RSC Adv., 2015

Simple and efficient concentrators are indispensable to the development of portable biosensor bas... more Simple and efficient concentrators are indispensable to the development of portable biosensor based detection platforms for the determination of microbial contamination in water.

Research paper thumbnail of Needle-free drop deposition: Role of elastic membranes

RSC Adv., 2015

Needle-free contact angle measurement of low-energy surfaces (superhydrophobic, superoleophobic, ... more Needle-free contact angle measurement of low-energy surfaces (superhydrophobic, superoleophobic, etc.) is critical for characterizing such substrates.