Natarajan S - Academia.edu (original) (raw)
Papers by Natarajan S
Materials Science and Engineering: C, 2013
The morphology of fibers synthesized through electrospinning has been found to mimic extracellula... more The morphology of fibers synthesized through electrospinning has been found to mimic extracellular matrix. Coaxially electrospun fibers of gelatin (sheath) coated poly (3-hydroxybutyric acid) (PHB) (core) was developed using 2,2,2 trifluoroethanol(TFE) and 1,1,1,3,3,3 hexafluoro-2-propanol(HFIP) as solvents respectively. The coaxial structure and coating of gelatin with PHB fibers was confirmed through transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thermal stability of the coaxially electrospun fibers was analyzed using thermogravimetric analysis(TGA), differential scanning calorimetry(DSC) and differential thermogravimetric analysis(DTA). Complete evaporation of solvent and gelatin grafting over PHB fibers was confirmed through attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR). The coaxially electrospun fibers exhibited competent tensile properties for skin regeneration with high surface area and porosity. In vitro degradation studies proved the stability of fibers and its potential applications in tissue engineering. The fibers supported the growth of human dermal fibroblasts and keratinocytes with normal morphology indicating its potential as a scaffold for skin regeneration.
Bookmarks Related papers MentionsView impact
SSRN Electronic Journal, 2021
Bookmarks Related papers MentionsView impact
Journal of Engineered Fibers and Fabrics, 2011
Electrospinning is one of the techniques to produce non-woven fiber mats using polymers. The diam... more Electrospinning is one of the techniques to produce non-woven fiber mats using polymers. The diameters of the fiber produced by this technique are in the range of 10 ^m to 10 nm. Electrically conducting ultra fine fibers are useful in many applications in the fields of sensors, and nanoelectronics. However, it is very difficult to obtain fibers of conducting polymers like polyaniline (PANI) and polypyrrole through electrospinning. Hence they are invariably mixed with other insulating polymers such as polymethylmethacrylate (PMMA) to obtain a conducting composite depending on the percolation of the conducting polymer. Here, we report the preparation of PANI-PMMA composite fibers by electrospinning. The scanning electron micrographs and the frequency dependent complex conductivity (σ*(ω)) of these polymer fibers are investigated at room temperature with different concentrations of PANI (5%, 10%, 15%, 20% w/w). It is observed that there is a significant enhancement in the ac conductivi...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Applied Physics Letters, 2015
Bookmarks Related papers MentionsView impact
Conference Record of the 1992 IEEE Industry Applications Society Annual Meeting
Abstract The authors describe the design of an automatic controller, based on the Intel 8748 sing... more Abstract The authors describe the design of an automatic controller, based on the Intel 8748 single-chip microprocessor, for a Stirling cycle nitrogen liquefying plant. The microcontroller has a real-time clock and a battery back-up system to monitor mains power failures and ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Biomaterials and Tissue Engineering, 2013
Bookmarks Related papers MentionsView impact
MRS Proceedings, 2005
ABSTRACTElectrospinning is a simple method of obtaining polymer fibers with nanometer diameter. T... more ABSTRACTElectrospinning is a simple method of obtaining polymer fibers with nanometer diameter. The increase in the ratio of surface area to volume in the case of such fibers, make them attractive in applications such as sensors, etc. It is difficult to electrospin Polypyrrole (PPy) directly to form fibers. Hence electrospinning is attempted with a composite formed with PPy and any other insulating polymer such as Polyethylene oxide (PEO), Polystyrene (PS), etc. The concentration of PPy can be varied to improve the electrical or sensing properties of the resulting composite. In the present report, the PEO-PPy composite fibers with different weight percentages (10% to 50% w/w) are prepared by electrospinning process. The fibers obtained are characterized using SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscopy). I-V Characteristics are studied for single and multiple aligned fibers obtained on gold electrodes. The variation of electrical conductivity with di...
Bookmarks Related papers MentionsView impact
Physical Review B, 1997
... G. Rangarajan Department of Physics, Indian Institute of Technology, Madras-600036, India Sol... more ... G. Rangarajan Department of Physics, Indian Institute of Technology, Madras-600036, India Soloman Thomas, PV Prabhakaran, and S ... PU blend has been investigated through measurements of temperature , temperature dependence of thermoelectric power (T) and electric ...
Bookmarks Related papers MentionsView impact
Conference on Physics and Technology of Semiconductor Devices and Integrated Circuits, 1992
Complex ac impedance measurements on Poly metallo phthalocyanines before heat treatment (I [MPc] ... more Complex ac impedance measurements on Poly metallo phthalocyanines before heat treatment (I [MPc] n (M equals Cu, Ni)) have been performed and the data analyzed using the Havriliak-Negami dispersion relation for polymers. The parameters so obtained are ...
Bookmarks Related papers MentionsView impact
Sensors and Actuators B: Chemical, 2013
ABSTRACT Tin oxide (SnO2) hollow nanofibers doped with cerium oxide (CeOx) were synthesized to st... more ABSTRACT Tin oxide (SnO2) hollow nanofibers doped with cerium oxide (CeOx) were synthesized to study the impact of CeO2 additives on their chemical sensing response. X-ray diffraction analysis and Raman scattering spectroscopic analysis showed that crystallization of CeO2 in the fiber composites was observed only when the Ce concentration was greater than 6 mol%. Also, maximum sensing response to ethanol was seen in the fiber composites with 6 mol% addition of Ce. Accordingly, we have discussed the possible explanations for this, including the role of crystalline CeO2 as a surface catalyst, and the role of hydrogen liberated during the dehydrogenation reaction of ethanol diffusing into the SnO2 lattice. The results obtained in this study indicate that SnO2-CeO2 nanofiber composites are potential candidates for use as high-sensitivity gas sensors.
Bookmarks Related papers MentionsView impact
Applied Physics Letters, 2014
Bookmarks Related papers MentionsView impact
Thin Solid Films, 2010
Bookmarks Related papers MentionsView impact
Solid State Communications, 1991
Bookmarks Related papers MentionsView impact
Separation and Purification Technology, 2010
We reported fabrication of electrospun nano-fibrous ion-exchange membrane (IEM) composed of sulfo... more We reported fabrication of electrospun nano-fibrous ion-exchange membrane (IEM) composed of sulfonated poly(ether ether ketone) (SPEEK). Prepared membrane was employed for electro-dialytic separation of Na+ from Mg2+ or Ca2+, which is an urgent problem for the production potable water from brackish water and chlor-alkali industries. Nano-fibrous membrane was successfully fabricated onto spun-bonded non-woven polypropylene fabric. Electrospun SPEEK (ESPEEK) and SPEEK thin film membrane's suitability, for the electro-dialytic separation of cations, was assessed by their conductivity measurements under different electrolytic environment using electrochemical impedance spectroscopy. Counter-ion transport number and membrane permselectivity were strongly depended on the nature of counter-ions. ESPEEK membrane showed very low selectivity (about negligible) for Mg2+ and Ca2+, because formation of nano-fibrous pore or channels, which restricted the migration of bi-valent cations. Additionally, very low flux and electro-transport efficiency for bi-valent cations in compare with Na+ across ESPEEK membrane, suggested its possible application for electro-driven separation of mono-valent and bi-valent electrolytes. Electrospun nano-fibrous IEMs may be the promising candidate for electro-dialytic selective separation of ions depending on their charge and hydrated ionic size.
Bookmarks Related papers MentionsView impact
Sensors and Actuators B: Chemical, 2012
Bookmarks Related papers MentionsView impact
Physics Letters A, 1991
Bookmarks Related papers MentionsView impact
Materials Science and Engineering: C, 1995
Bookmarks Related papers MentionsView impact
Materials Letters, 2011
Here we report an approach to fabricate flexible polymer self standing films embedded with contin... more Here we report an approach to fabricate flexible polymer self standing films embedded with continuous aligned microtubes/microchannels via electrospinning. The scheme is to wash the electrospun fibers selectively to form either microtubes/microchannels. Optical microscope (OM) and Scanning electron microscope images are evident for the well aligned microtubes and microchannels respectively with a diameter of ~8μm and a length of ~4cm. Meniscus of tetrahydrofuran in the microtubes can be observed explicitly in the OM images. Mutually perpendicular microtubes are also fabricated on a polymer film. Angular distribution of aligned microstructures indicates the standard deviation is not more than 1°. These tubes/channels can be potential for tissue engineering as they could provide a directional template for the growth when a biodegradable polymer such as Poly(vinylalcohol) is used.
Bookmarks Related papers MentionsView impact
Materials Science and Engineering: C, 2013
The morphology of fibers synthesized through electrospinning has been found to mimic extracellula... more The morphology of fibers synthesized through electrospinning has been found to mimic extracellular matrix. Coaxially electrospun fibers of gelatin (sheath) coated poly (3-hydroxybutyric acid) (PHB) (core) was developed using 2,2,2 trifluoroethanol(TFE) and 1,1,1,3,3,3 hexafluoro-2-propanol(HFIP) as solvents respectively. The coaxial structure and coating of gelatin with PHB fibers was confirmed through transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thermal stability of the coaxially electrospun fibers was analyzed using thermogravimetric analysis(TGA), differential scanning calorimetry(DSC) and differential thermogravimetric analysis(DTA). Complete evaporation of solvent and gelatin grafting over PHB fibers was confirmed through attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR). The coaxially electrospun fibers exhibited competent tensile properties for skin regeneration with high surface area and porosity. In vitro degradation studies proved the stability of fibers and its potential applications in tissue engineering. The fibers supported the growth of human dermal fibroblasts and keratinocytes with normal morphology indicating its potential as a scaffold for skin regeneration.
Bookmarks Related papers MentionsView impact
SSRN Electronic Journal, 2021
Bookmarks Related papers MentionsView impact
Journal of Engineered Fibers and Fabrics, 2011
Electrospinning is one of the techniques to produce non-woven fiber mats using polymers. The diam... more Electrospinning is one of the techniques to produce non-woven fiber mats using polymers. The diameters of the fiber produced by this technique are in the range of 10 ^m to 10 nm. Electrically conducting ultra fine fibers are useful in many applications in the fields of sensors, and nanoelectronics. However, it is very difficult to obtain fibers of conducting polymers like polyaniline (PANI) and polypyrrole through electrospinning. Hence they are invariably mixed with other insulating polymers such as polymethylmethacrylate (PMMA) to obtain a conducting composite depending on the percolation of the conducting polymer. Here, we report the preparation of PANI-PMMA composite fibers by electrospinning. The scanning electron micrographs and the frequency dependent complex conductivity (σ*(ω)) of these polymer fibers are investigated at room temperature with different concentrations of PANI (5%, 10%, 15%, 20% w/w). It is observed that there is a significant enhancement in the ac conductivi...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Applied Physics Letters, 2015
Bookmarks Related papers MentionsView impact
Conference Record of the 1992 IEEE Industry Applications Society Annual Meeting
Abstract The authors describe the design of an automatic controller, based on the Intel 8748 sing... more Abstract The authors describe the design of an automatic controller, based on the Intel 8748 single-chip microprocessor, for a Stirling cycle nitrogen liquefying plant. The microcontroller has a real-time clock and a battery back-up system to monitor mains power failures and ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Biomaterials and Tissue Engineering, 2013
Bookmarks Related papers MentionsView impact
MRS Proceedings, 2005
ABSTRACTElectrospinning is a simple method of obtaining polymer fibers with nanometer diameter. T... more ABSTRACTElectrospinning is a simple method of obtaining polymer fibers with nanometer diameter. The increase in the ratio of surface area to volume in the case of such fibers, make them attractive in applications such as sensors, etc. It is difficult to electrospin Polypyrrole (PPy) directly to form fibers. Hence electrospinning is attempted with a composite formed with PPy and any other insulating polymer such as Polyethylene oxide (PEO), Polystyrene (PS), etc. The concentration of PPy can be varied to improve the electrical or sensing properties of the resulting composite. In the present report, the PEO-PPy composite fibers with different weight percentages (10% to 50% w/w) are prepared by electrospinning process. The fibers obtained are characterized using SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscopy). I-V Characteristics are studied for single and multiple aligned fibers obtained on gold electrodes. The variation of electrical conductivity with di...
Bookmarks Related papers MentionsView impact
Physical Review B, 1997
... G. Rangarajan Department of Physics, Indian Institute of Technology, Madras-600036, India Sol... more ... G. Rangarajan Department of Physics, Indian Institute of Technology, Madras-600036, India Soloman Thomas, PV Prabhakaran, and S ... PU blend has been investigated through measurements of temperature , temperature dependence of thermoelectric power (T) and electric ...
Bookmarks Related papers MentionsView impact
Conference on Physics and Technology of Semiconductor Devices and Integrated Circuits, 1992
Complex ac impedance measurements on Poly metallo phthalocyanines before heat treatment (I [MPc] ... more Complex ac impedance measurements on Poly metallo phthalocyanines before heat treatment (I [MPc] n (M equals Cu, Ni)) have been performed and the data analyzed using the Havriliak-Negami dispersion relation for polymers. The parameters so obtained are ...
Bookmarks Related papers MentionsView impact
Sensors and Actuators B: Chemical, 2013
ABSTRACT Tin oxide (SnO2) hollow nanofibers doped with cerium oxide (CeOx) were synthesized to st... more ABSTRACT Tin oxide (SnO2) hollow nanofibers doped with cerium oxide (CeOx) were synthesized to study the impact of CeO2 additives on their chemical sensing response. X-ray diffraction analysis and Raman scattering spectroscopic analysis showed that crystallization of CeO2 in the fiber composites was observed only when the Ce concentration was greater than 6 mol%. Also, maximum sensing response to ethanol was seen in the fiber composites with 6 mol% addition of Ce. Accordingly, we have discussed the possible explanations for this, including the role of crystalline CeO2 as a surface catalyst, and the role of hydrogen liberated during the dehydrogenation reaction of ethanol diffusing into the SnO2 lattice. The results obtained in this study indicate that SnO2-CeO2 nanofiber composites are potential candidates for use as high-sensitivity gas sensors.
Bookmarks Related papers MentionsView impact
Applied Physics Letters, 2014
Bookmarks Related papers MentionsView impact
Thin Solid Films, 2010
Bookmarks Related papers MentionsView impact
Solid State Communications, 1991
Bookmarks Related papers MentionsView impact
Separation and Purification Technology, 2010
We reported fabrication of electrospun nano-fibrous ion-exchange membrane (IEM) composed of sulfo... more We reported fabrication of electrospun nano-fibrous ion-exchange membrane (IEM) composed of sulfonated poly(ether ether ketone) (SPEEK). Prepared membrane was employed for electro-dialytic separation of Na+ from Mg2+ or Ca2+, which is an urgent problem for the production potable water from brackish water and chlor-alkali industries. Nano-fibrous membrane was successfully fabricated onto spun-bonded non-woven polypropylene fabric. Electrospun SPEEK (ESPEEK) and SPEEK thin film membrane's suitability, for the electro-dialytic separation of cations, was assessed by their conductivity measurements under different electrolytic environment using electrochemical impedance spectroscopy. Counter-ion transport number and membrane permselectivity were strongly depended on the nature of counter-ions. ESPEEK membrane showed very low selectivity (about negligible) for Mg2+ and Ca2+, because formation of nano-fibrous pore or channels, which restricted the migration of bi-valent cations. Additionally, very low flux and electro-transport efficiency for bi-valent cations in compare with Na+ across ESPEEK membrane, suggested its possible application for electro-driven separation of mono-valent and bi-valent electrolytes. Electrospun nano-fibrous IEMs may be the promising candidate for electro-dialytic selective separation of ions depending on their charge and hydrated ionic size.
Bookmarks Related papers MentionsView impact
Sensors and Actuators B: Chemical, 2012
Bookmarks Related papers MentionsView impact
Physics Letters A, 1991
Bookmarks Related papers MentionsView impact
Materials Science and Engineering: C, 1995
Bookmarks Related papers MentionsView impact
Materials Letters, 2011
Here we report an approach to fabricate flexible polymer self standing films embedded with contin... more Here we report an approach to fabricate flexible polymer self standing films embedded with continuous aligned microtubes/microchannels via electrospinning. The scheme is to wash the electrospun fibers selectively to form either microtubes/microchannels. Optical microscope (OM) and Scanning electron microscope images are evident for the well aligned microtubes and microchannels respectively with a diameter of ~8μm and a length of ~4cm. Meniscus of tetrahydrofuran in the microtubes can be observed explicitly in the OM images. Mutually perpendicular microtubes are also fabricated on a polymer film. Angular distribution of aligned microstructures indicates the standard deviation is not more than 1°. These tubes/channels can be potential for tissue engineering as they could provide a directional template for the growth when a biodegradable polymer such as Poly(vinylalcohol) is used.
Bookmarks Related papers MentionsView impact