Praveen Sekhar | Washington State University (original) (raw)

Papers by Praveen Sekhar

In this work, an electrochemical bio-sensor using aligned silica nanowires in a micro-fluidic pla... more In this work, an electrochemical bio-sensor using aligned silica nanowires in a micro-fluidic platform is proposed. It serves to accurately and rapidly detect targeted species such as hepatitis B, essential for the early detection of lung cancers with high sensitivity. The silica nanowires were grown selectively on Si wafer using ion implantation based novel seeding methodology following a VLS growth model..1 This particular approach not only helps to spatially resolve the specific reaction sites but also vary the size and distribution of nanowires through controlled annealing after ion implantation. Further, silica nanowires were modified with specific antibody to IL10 (interleukin 10) cytokine. The corresponding change in the electronic properties of these wires, as a result of selective binding of cancer marker proteins, is measured using square wave voltammetry (SWV) technique,. The antibody receptor modified silica nanowires serves as a working electrode, while a Pt counter ele...

Abstract In this work, we present recent progress in our work to develop new sensors and sensing ... more Abstract In this work, we present recent progress in our work to develop new sensors and sensing technology for future hydrogen powered fuel cell vehicles. The first device is an electrochemical mixed potential sensor based on an indium-tin oxide/YSZ/Pt configuration prototype fabricated using commercial ceramic sensor manufacturing methods. This sensor has been designed to detect hydrogen in air and may serve in safety systems for vehicles or as a component of hydrogen infrastructure.

Abstract In recent years, research on development of chemical, biological and hazardous gas senso... more Abstract In recent years, research on development of chemical, biological and hazardous gas sensors for homeland security have attracted great deal of interest. Actuators possessing high sensitivity, easy fabrication techniques and excellent integration compatibility are in great demand.

Abstract Infrared optical emission from erbium-doped silica nanowires is shown to have property c... more Abstract Infrared optical emission from erbium-doped silica nanowires is shown to have property characteristic of the material nanostructure and to provide the basis for the fabrication of integrated photonic devices and biosensors. Silica nanowires of approximately 150 nm diameter were grown on a silicon wafer by metal-induced growth using a thin (20 nm) sputter-deposited palladium layer as a catalyst.

Optically-active silica nanowires are produced by metal-induced growth on silicon substrates usin... more Optically-active silica nanowires are produced by metal-induced growth on silicon substrates using ion-implantation, with two different strategies employed for their fabrication. The first is based on Er implantation of nanowires produced by a thin-film Pd catalyst layer, and the second employing implanted Er as both the catalyst and dopant. The luminescence properties of the resulting Er-doped silica nanowires are reported and compared with similarly implanted fused silica samples.

The process parameters of a nanoporous silicon-based Pd-doped H2 system were varied to investigat... more The process parameters of a nanoporous silicon-based Pd-doped H2 system were varied to investigate the sensor response. In particular, the influence of anodization current density, etching time and active layer (Pd) thickness were correlated to the sensor's response time and stability. The structure and morphology of the pores along with Pd distribution in the porous matrix has been found to govern the sensor response.

Abstract: The process parameters of impedance based Pd doped porous silicon sensor were varied to... more Abstract: The process parameters of impedance based Pd doped porous silicon sensor were varied to optimize the sensitivity towards hydrogen detection. The active (Pd) layer thickness and pore depth were found to critically influence the sensitivity. The sensor was tested in the range of 0-1.5% H2. The optimized Pd thickness was found to be 8 nm with pore depth correlating to an etching time of 30 mins. Keywords: Hydrogen Sensor, Palladium Nanoclusters, Nanowires, Morphology

Recent developments in the search for renewable energy coupled with the advancements in fuel cell... more Recent developments in the search for renewable energy coupled with the advancements in fuel cell powered vehicles have augmented the demand for hydrogen safety sensors [1]. There are several sensor technologies that have been developed to detect hydrogen, including deployed systems to detect leaks in manned space systems and hydrogen safety sensors for laboratory and industrial usage.

Recent developments in the search for renewable energy coupled with the advancements in fuel cell... more Recent developments in the search for renewable energy coupled with the advancements in fuel cell vehicles (FCVs) have augmented the demand for hydrogen safety sensors [1]. There are several sensor technologies that have been developed to detect hydrogen, including deployed systems to detect leaks in manned space systems and hydrogen safety sensors for laboratory and industrial usage.

Optically active SiO x nanowires were grown on silicon by ion-implanting it with metallic impurit... more Optically active SiO x nanowires were grown on silicon by ion-implanting it with metallic impurities and annealed at 1100° C in an Ar ambient. The implanted metals precipitate on the silicon surface and act as catalysts for nanowire growth. Ion implantation of erbium into silicon and subsequent heating in an argon ambient resulted in selective nucleation and growth of optically active silica nanowires.

▪ Remainder of FY11 into FY12: Sensor electronics for Round 2 NREL testing, protocol for on-board... more ▪ Remainder of FY11 into FY12: Sensor electronics for Round 2 NREL testing, protocol for on-board temperature control, updating existing packaging scheme to incorporate electronics and temperature control, continue electrochemical and long-term aging evaluation of both pre-commercial and laboratory prototypes, continue cross-sensitivity studies to ensure desired sensor performance and accuracy.

Reliable, low-cost hydrogen sensors are crucial for existing and emerging energy applications tha... more Reliable, low-cost hydrogen sensors are crucial for existing and emerging energy applications that address issues of human safety and infrastructure reliability. As a versatile energy carrier, hydrogen can be produced from both renewable and non-renewable sources. It can be stored as a fuel for use in transportation and distributed heat and power generation systems, with water being the only by-product. When mixed with air, 4-75 vol% of hydrogen is flammable. Safety sensors are needed that will detect the unintentional release of ...

The abstract reports on the packaging scheme and subsequent testing of an electrochemical, potent... more The abstract reports on the packaging scheme and subsequent testing of an electrochemical, potentiometric H2 safety sensor for infrastructure and automotive applications. In this study, a non-Nernstian H2 sensor based on Indium Tin Oxide (ITO) and Pt electrodes and Yttria-Stabilized Zirconia electrolyte was developed, packaged, and tested. The H2 sensor prototype is based on a unique LANL mixed potential sensor design1.

Non-conventional thin film based Surface Acoustic Wave (SAW) actuators have gained immense import... more Non-conventional thin film based Surface Acoustic Wave (SAW) actuators have gained immense importance in the field of resonant acoustic MEMS devices. The need to realize low loss SAW resonators on non-piezoelectric substrates require actuator thin films with superior piezoelectric properties. Numerous research studies have focused on developing highly oriented piezoelectric films such as ZnO, AlN [1, 2]. It is a known fact that sol-gel derived Lead Zirconate Titanate (PZT) films offer better piezoelectric properties when ...

Page 1. LA-UR-/0-05#-/ Approved for public release; distribution is unlimited. ~ LosAla,mos NATIO... more Page 1. LA-UR-/0-05#-/ Approved for public release; distribution is unlimited. ~ LosAla,mos NATIONAL LABORATORY - - - EST.1943 - - - Title: Development of a Reliable, Miniaturized Hydrogen Safety Sensor Prototype Author ...

Yttria Stabilized Zirconia (YSZ) has been routinely used as a solid electrolyte in high temperatu... more Yttria Stabilized Zirconia (YSZ) has been routinely used as a solid electrolyte in high temperature electrochemical gas sensing applications1-2. LANL has studied and developed mixed potential sensors for detecting NOX, ammonia, hydrogen and hydrocarbons based on a YSZ electrolyte 3-6. Initial YSZ tape cast platforms with screen-printed metal oxide and Pt sensor electrodes have shown promising results, but also clearly show the need to optimize electrolyte morphologies and interfaces in order to demonstrate a sensitive, selective, and ...

The article reports on a new conditioning technique referred to as the pulsed discharge technique... more The article reports on a new conditioning technique referred to as the pulsed discharge technique to improve the performance of non-Nernstian potentiometric sensors. In this method, the sensor is energized through a series of positive and negative pulses between the electrodes with discharge phases in between. The sensor response is extracted from the discharge characteristics, which depend on the type of gas and its concentration. The data is presented as a combination of variables derived form the discharge characteristics. In this study, a 'La 0.8 Sr 0.2 CrO 3 /YSZ/Pt' sensor configuration was used to investigate this technique.

Electrochemical Society …, Jan 1, 2010

Journal of Electrochemical …, Jan 1, 2003

The purpose of this research effort is to explore and demonstrate the use of a novel, BJR Sensors... more The purpose of this research effort is to explore and demonstrate the use of a novel, BJR Sensors patented pulsed discharge technique (PDT) 1 for manufacturing of stable, selective and sensitive mixed potential2 gas sensors. PDT compliments the existing unique, patented LANL mixed potential sensor design and platform conducive for commercialization3. Electrochemical gas sensors developed at LANL have been demonstrated to sense NOx 4, hydrocarbons5, CO6 and H2 7 at elevated temperatures. Successful integration of the ...

DOE Scientific and Technical Information. DOE Scientific and Technical Information. ...

In this work, an electrochemical bio-sensor using aligned silica nanowires in a micro-fluidic pla... more In this work, an electrochemical bio-sensor using aligned silica nanowires in a micro-fluidic platform is proposed. It serves to accurately and rapidly detect targeted species such as hepatitis B, essential for the early detection of lung cancers with high sensitivity. The silica nanowires were grown selectively on Si wafer using ion implantation based novel seeding methodology following a VLS growth model..1 This particular approach not only helps to spatially resolve the specific reaction sites but also vary the size and distribution of nanowires through controlled annealing after ion implantation. Further, silica nanowires were modified with specific antibody to IL10 (interleukin 10) cytokine. The corresponding change in the electronic properties of these wires, as a result of selective binding of cancer marker proteins, is measured using square wave voltammetry (SWV) technique,. The antibody receptor modified silica nanowires serves as a working electrode, while a Pt counter ele...

Abstract In this work, we present recent progress in our work to develop new sensors and sensing ... more Abstract In this work, we present recent progress in our work to develop new sensors and sensing technology for future hydrogen powered fuel cell vehicles. The first device is an electrochemical mixed potential sensor based on an indium-tin oxide/YSZ/Pt configuration prototype fabricated using commercial ceramic sensor manufacturing methods. This sensor has been designed to detect hydrogen in air and may serve in safety systems for vehicles or as a component of hydrogen infrastructure.

Abstract In recent years, research on development of chemical, biological and hazardous gas senso... more Abstract In recent years, research on development of chemical, biological and hazardous gas sensors for homeland security have attracted great deal of interest. Actuators possessing high sensitivity, easy fabrication techniques and excellent integration compatibility are in great demand.

Abstract Infrared optical emission from erbium-doped silica nanowires is shown to have property c... more Abstract Infrared optical emission from erbium-doped silica nanowires is shown to have property characteristic of the material nanostructure and to provide the basis for the fabrication of integrated photonic devices and biosensors. Silica nanowires of approximately 150 nm diameter were grown on a silicon wafer by metal-induced growth using a thin (20 nm) sputter-deposited palladium layer as a catalyst.

Optically-active silica nanowires are produced by metal-induced growth on silicon substrates usin... more Optically-active silica nanowires are produced by metal-induced growth on silicon substrates using ion-implantation, with two different strategies employed for their fabrication. The first is based on Er implantation of nanowires produced by a thin-film Pd catalyst layer, and the second employing implanted Er as both the catalyst and dopant. The luminescence properties of the resulting Er-doped silica nanowires are reported and compared with similarly implanted fused silica samples.

The process parameters of a nanoporous silicon-based Pd-doped H2 system were varied to investigat... more The process parameters of a nanoporous silicon-based Pd-doped H2 system were varied to investigate the sensor response. In particular, the influence of anodization current density, etching time and active layer (Pd) thickness were correlated to the sensor's response time and stability. The structure and morphology of the pores along with Pd distribution in the porous matrix has been found to govern the sensor response.

Abstract: The process parameters of impedance based Pd doped porous silicon sensor were varied to... more Abstract: The process parameters of impedance based Pd doped porous silicon sensor were varied to optimize the sensitivity towards hydrogen detection. The active (Pd) layer thickness and pore depth were found to critically influence the sensitivity. The sensor was tested in the range of 0-1.5% H2. The optimized Pd thickness was found to be 8 nm with pore depth correlating to an etching time of 30 mins. Keywords: Hydrogen Sensor, Palladium Nanoclusters, Nanowires, Morphology

Recent developments in the search for renewable energy coupled with the advancements in fuel cell... more Recent developments in the search for renewable energy coupled with the advancements in fuel cell powered vehicles have augmented the demand for hydrogen safety sensors [1]. There are several sensor technologies that have been developed to detect hydrogen, including deployed systems to detect leaks in manned space systems and hydrogen safety sensors for laboratory and industrial usage.

Recent developments in the search for renewable energy coupled with the advancements in fuel cell... more Recent developments in the search for renewable energy coupled with the advancements in fuel cell vehicles (FCVs) have augmented the demand for hydrogen safety sensors [1]. There are several sensor technologies that have been developed to detect hydrogen, including deployed systems to detect leaks in manned space systems and hydrogen safety sensors for laboratory and industrial usage.

Optically active SiO x nanowires were grown on silicon by ion-implanting it with metallic impurit... more Optically active SiO x nanowires were grown on silicon by ion-implanting it with metallic impurities and annealed at 1100° C in an Ar ambient. The implanted metals precipitate on the silicon surface and act as catalysts for nanowire growth. Ion implantation of erbium into silicon and subsequent heating in an argon ambient resulted in selective nucleation and growth of optically active silica nanowires.

▪ Remainder of FY11 into FY12: Sensor electronics for Round 2 NREL testing, protocol for on-board... more ▪ Remainder of FY11 into FY12: Sensor electronics for Round 2 NREL testing, protocol for on-board temperature control, updating existing packaging scheme to incorporate electronics and temperature control, continue electrochemical and long-term aging evaluation of both pre-commercial and laboratory prototypes, continue cross-sensitivity studies to ensure desired sensor performance and accuracy.

Reliable, low-cost hydrogen sensors are crucial for existing and emerging energy applications tha... more Reliable, low-cost hydrogen sensors are crucial for existing and emerging energy applications that address issues of human safety and infrastructure reliability. As a versatile energy carrier, hydrogen can be produced from both renewable and non-renewable sources. It can be stored as a fuel for use in transportation and distributed heat and power generation systems, with water being the only by-product. When mixed with air, 4-75 vol% of hydrogen is flammable. Safety sensors are needed that will detect the unintentional release of ...

The abstract reports on the packaging scheme and subsequent testing of an electrochemical, potent... more The abstract reports on the packaging scheme and subsequent testing of an electrochemical, potentiometric H2 safety sensor for infrastructure and automotive applications. In this study, a non-Nernstian H2 sensor based on Indium Tin Oxide (ITO) and Pt electrodes and Yttria-Stabilized Zirconia electrolyte was developed, packaged, and tested. The H2 sensor prototype is based on a unique LANL mixed potential sensor design1.

Non-conventional thin film based Surface Acoustic Wave (SAW) actuators have gained immense import... more Non-conventional thin film based Surface Acoustic Wave (SAW) actuators have gained immense importance in the field of resonant acoustic MEMS devices. The need to realize low loss SAW resonators on non-piezoelectric substrates require actuator thin films with superior piezoelectric properties. Numerous research studies have focused on developing highly oriented piezoelectric films such as ZnO, AlN [1, 2]. It is a known fact that sol-gel derived Lead Zirconate Titanate (PZT) films offer better piezoelectric properties when ...

Page 1. LA-UR-/0-05#-/ Approved for public release; distribution is unlimited. ~ LosAla,mos NATIO... more Page 1. LA-UR-/0-05#-/ Approved for public release; distribution is unlimited. ~ LosAla,mos NATIONAL LABORATORY - - - EST.1943 - - - Title: Development of a Reliable, Miniaturized Hydrogen Safety Sensor Prototype Author ...

Yttria Stabilized Zirconia (YSZ) has been routinely used as a solid electrolyte in high temperatu... more Yttria Stabilized Zirconia (YSZ) has been routinely used as a solid electrolyte in high temperature electrochemical gas sensing applications1-2. LANL has studied and developed mixed potential sensors for detecting NOX, ammonia, hydrogen and hydrocarbons based on a YSZ electrolyte 3-6. Initial YSZ tape cast platforms with screen-printed metal oxide and Pt sensor electrodes have shown promising results, but also clearly show the need to optimize electrolyte morphologies and interfaces in order to demonstrate a sensitive, selective, and ...

The article reports on a new conditioning technique referred to as the pulsed discharge technique... more The article reports on a new conditioning technique referred to as the pulsed discharge technique to improve the performance of non-Nernstian potentiometric sensors. In this method, the sensor is energized through a series of positive and negative pulses between the electrodes with discharge phases in between. The sensor response is extracted from the discharge characteristics, which depend on the type of gas and its concentration. The data is presented as a combination of variables derived form the discharge characteristics. In this study, a 'La 0.8 Sr 0.2 CrO 3 /YSZ/Pt' sensor configuration was used to investigate this technique.

Electrochemical Society …, Jan 1, 2010

Journal of Electrochemical …, Jan 1, 2003

The purpose of this research effort is to explore and demonstrate the use of a novel, BJR Sensors... more The purpose of this research effort is to explore and demonstrate the use of a novel, BJR Sensors patented pulsed discharge technique (PDT) 1 for manufacturing of stable, selective and sensitive mixed potential2 gas sensors. PDT compliments the existing unique, patented LANL mixed potential sensor design and platform conducive for commercialization3. Electrochemical gas sensors developed at LANL have been demonstrated to sense NOx 4, hydrocarbons5, CO6 and H2 7 at elevated temperatures. Successful integration of the ...

DOE Scientific and Technical Information. DOE Scientific and Technical Information. ...