Investigation of Oxide-Removal of Various Metal Particles for Fabricating MEMS-Based Corrosion Sensor

2009 ◽  
Author(s):  
Feng Pan ◽  
Adam Huang
Keyword(s):  
Oxide Coating ◽  
Metal Particles ◽  
Operating Life ◽  
Metallic Particles ◽  
Sensing Material ◽  
Corrosion Sensor ◽  
Mems Fabrication ◽  
Wide Range ◽  
Titanium Aluminum ◽  
Oxide Removal

Recently, our research group has proposed a MEMS-based solid state corrosion sensor, which is based on embedding metal particle into elastomeric polymers to form a composite-based sensing material. The chemical and dimensional properties of the metal particles and polymer matrix will provide the tailorability in sensor sensitivity, selectivity, time response, and operating life-span. However, the oxidization of metallic particles prior to embedding is adverse for electrical transduction of such sensor. This paper will be based on the investigation of chemical etching protocols used to remove the oxide coating from metal particles without adversely alter the particle itself. The etching process must also be compatible with common MEMS fabrication processes and not limited by the wide range of particle sizes used (30nm–100um). More specifically, metal particles such as Titanium, Aluminum, Nickel, and Stainless Steel are currently being used and investigated.

scholarly journals Synthesis of Micro- and Nanoparticles in Sub- and Supercritical Water: From the Laboratory to Larger Scales

2020 ◽  
Vol 10 (16) ◽  
pp. 5508
Author(s):  
F. Ruiz-Jorge ◽  
J. R. Portela ◽  
J. Sánchez-Oneto ◽  
E. J. Martínez de la Ossa
Keyword(s):  
Supercritical Fluids ◽  
Supercritical Water ◽  
Metal Particles ◽  
High Pressure And Temperature ◽  
Particle Generation ◽  
Innovative Method ◽  
Wide Range ◽  
Active Research ◽  
Main Operating ◽  
Temperature Water

The use of micro- and nanoparticles is gaining more and more importance because of their wide range of uses and benefits based on their unique mechanical, physical, electrical, optical, electronic, and magnetic properties. In recent decades, supercritical fluid technologies have strongly emerged as an effective alternative to other numerous particle generation processes, mainly thanks to the peculiar properties exhibited by supercritical fluids. Carbon dioxide and water have so far been two of the most commonly used fluids for particle generation, the former being the fluid par excellence in this field, mainly, because it offers the possibility of precipitating thermolabile particles. Nevertheless, the use of high-pressure and -temperature water opens an innovative and very interesting field of study, especially with regards to the precipitation of particles that could hardly be precipitated when CO2 is used, such as metal particles with a considerable value in the market. This review describes an innovative method to obtain micro- and nanoparticles: hydrothermal synthesis by means of near and supercritical water. It also describes the differences between this method and other conventional procedures, the most currently active research centers, the types of particles synthesized, the techniques to evaluate the products obtained, the main operating parameters, the types of reactors, and amongst them, the most significant and the most frequently used, the scaling-up studies under progress, and the milestones to be reached in the coming years.

Measurements and Modeling of Ingress in a New 1.5-Stage Turbine Research Facility

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Marios Patinios ◽  
James A. Scobie ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Theoretical Model ◽  
Gas Turbines ◽  
Test Facility ◽  
Radial Clearance ◽  
Operating Life ◽  
The Core ◽  
Wide Range ◽  
Purge Flow ◽  
Rotor Disk ◽  
Engine Components

In gas turbines, hot mainstream flow can be ingested into the wheel-space formed between stator and rotor disks as a result of the circumferential pressure asymmetry in the annulus; this ingress can significantly affect the operating life, performance, and integrity of highly stressed, vulnerable engine components. Rim seals, fitted at the periphery of the disks, are used to minimize ingress and therefore reduce the amount of purge flow required to seal the wheel-space and cool the disks. This paper presents experimental results from a new 1.5-stage test facility designed to investigate ingress into the wheel-spaces upstream and downstream of a rotor disk. The fluid-dynamically scaled rig operates at incompressible flow conditions, far removed from the harsh environment of the engine which is not conducive to experimental measurements. The test facility features interchangeable rim-seal components, offering significant flexibility and expediency in terms of data collection over a wide range of sealing flow rates. The rig was specifically designed to enable an efficient method of ranking and quantifying the performance of generic and engine-specific seal geometries. The radial variation of CO2 gas concentration, pressure, and swirl is measured to explore, for the first time, the flow structure in both the upstream and downstream wheel-spaces. The measurements show that the concentration in the core is equal to that on the stator walls and that both distributions are virtually invariant with radius. These measurements confirm that mixing between ingress and egress is essentially complete immediately after the ingested fluid enters the wheel-space and that the fluid from the boundary layer on the stator is the source of that in the core. The swirl in the core is shown to determine the radial distribution of pressure in the wheel-space. The performance of a double radial-clearance seal is evaluated in terms of the variation of effectiveness with sealing flow rate for both the upstream and the downstream wheel-spaces and is found to be independent of rotational Reynolds number. A simple theoretical orifice model was fitted to the experimental data showing good agreement between theory and experiment for all cases. This observation is of great significance as it demonstrates that the theoretical model can accurately predict ingress even when it is driven by the complex unsteady pressure field in the annulus upstream and downstream of the rotor. The combination of the theoretical model and the new test rig with its flexibility and capability for detailed measurements provides a powerful tool for the engine rim-seal designer.

scholarly journals Fiber Optical Hydrogen Sensor Based on WO3-Pd2Pt-Pt Nanocomposite Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 128
Author(s):  
Jixiang Dai ◽  
Yi Li ◽  
Hongbo Ruan ◽  
Zhuang Ye ◽  
Nianyao Chai ◽  
...  
Keyword(s):  
Optical Power ◽  
Single Mode ◽  
Hydrogen Sensor ◽  
Single Mode Fiber ◽  
Nanocomposite Films ◽  
Electric Signal ◽  
Hydrogen Sensing ◽  
Air Atmosphere ◽  
Sensing Material ◽  
Wide Range

In this paper, WO3-Pd2Pt-Pt nanocomposite films were deposited on a single mode fiber as the hydrogen sensing material, which changes its reflectivity under different hydrogen concentration. The reflectivity variation was probed and converted to an electric signal by a pair of balanced InGaAs photoelectric detectors. In addition, the performance of the WO3-Pd2Pt-Pt composite film was investigated under different optical powers, and the irrigating power was optimized at 5 mW. With the irrigation of this optical power, the hydrogen sensitive film exhibits quick response toward 100 ppm hydrogen in air atmosphere at a room temperature of 25 °C. The experimental results demonstrate a high resolution at 5 parts per million (ppm) within a wide range from 100 to 5000 ppm in air. This simple and compact sensing system can detect hydrogen concentrations far below the explosion limit and provide early alert for hydrogen leakage, showing great potential in hydrogen-related applications.

Measurements and Modelling of Ingress in a New 1.5-Stage Turbine Research Facility

2016 ◽  
Author(s):  
Marios Patinios ◽  
James A. Scobie ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Theoretical Model ◽  
Gas Turbines ◽  
Test Facility ◽  
Radial Clearance ◽  
Operating Life ◽  
The Core ◽  
Wide Range ◽  
Purge Flow ◽  
Engine Components ◽  
First Time

In gas turbines, hot mainstream flow can be ingested into the wheel-space formed between stator and rotor discs as a result of the circumferential pressure asymmetry in the annulus; this ingress can significantly affect the operating life, performance and integrity of highly-stressed, vulnerable engine components. Rim seals, fitted at the periphery of the discs, are used to minimise ingress and therefore reduce the amount of purge flow required to seal the wheel-space and cool the discs. This paper presents experimental results from a new 1.5-stage test facility designed to investigate ingress into the wheel-spaces upstream and downstream of a rotor disc. The fluid-dynamically-scaled rig operates at incompressible flow conditions, far removed from the harsh environment of the engine which is not conducive to experimental measurements. The test facility features interchangeable rim-seal components, offering significant flexibility and expediency in terms of data collection over a wide range of sealing-flow rates. The rig was specifically designed to enable an efficient method of ranking and quantifying the performance of generic and engine-specific seal geometries. The radial variation of CO2 gas concentration, pressure and swirl is measured to explore, for the first time, the flow structure in both the upstream and downstream wheel-spaces. The measurements show that the concentration in the core is equal to that on the stator walls and that both distributions are virtually invariant with radius. These measurements confirm that mixing between ingress and egress is essentially complete immediately after the ingested fluid enters the wheel-space and that the fluid from the boundary-layer on the stator is the source of that in the core. The swirl in the core is shown to determine the radial distribution of pressure in the wheel-space. The performance of a double radial-clearance seal is evaluated in terms of the variation of effectiveness with sealing flow rate for both the upstream and the downstream wheel-spaces and is found to be independent of rotational Reynolds number. A simple theoretical orifice model was fitted to the experimental data showing good agreement between theory and experiment for all cases. This observation is of great significance as it demonstrates that the theoretical model can accurately predict ingress even when it is driven by the complex unsteady pressure field in the annulus upstream and downstream of the rotor. The combination of the theoretical model and the new test rig with its flexibility and capability for detailed measurements provides a powerful tool for the engine rim-seal designer.

Solvent-Based Polymer Swelling Characterization for the Development of the Nano/Micro-Particle Polymer Composite MEMS Corrosion Sensor

2014 ◽  
Author(s):  
Feng Pan ◽  
Abdoul Kader Maiga ◽  
Po-Hao Adam Huang
Keyword(s):  
Reaction Products ◽  
Material Transport ◽  
Sensing Element ◽  
Micro Electro Mechanical Systems ◽  
Polymer Swelling ◽  
Corrosion Sensor ◽  
Mems Technology ◽  
New Type ◽  
Oxide Removal

The concept of using Micro-Electro-Mechanical Systems (MEMS) for in-situ corrosion sensing and for long-term applications has been proposed and is currently under development by our research lab. This is a new type of sensing using MEMS technology and, to the knowledge of our team, has not been explored previously. The MEMS corrosion sensor is based on the oxidation of metal nano/micro-particle embedded in elastomeric polymer to form a composite sensing element. The polymer controls the diffusion into and out of the sensor while the corrosion of the metal particles inhibits electrical conduction which is used as the detection signal. The work presented here is based on part of the methods developed for the removal of native and process-induced metal oxides. A major aspect is the study of the swelling dynamics of the polymer matrix (polydimethylsiloxane, PDMS) intended for enhancing material transport of etchants into and reaction products out of the composite during oxide removal. More specifically, the characterization of the swelling of copper particles-PDMS composite samples in liquid solvent baths is presented.

scholarly journals Two-Dimensional Optical Metasurfaces: From Plasmons to Dielectrics

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Bo Liu ◽  
Kerui Song ◽  
Jiangnan Xiao
Keyword(s):  
Metal Particles ◽  
Subwavelength Structures ◽  
Metal Structures ◽  
Unit Structure ◽  
Wide Range ◽  
Different Types ◽  
Working Principle ◽  
Physical Fields ◽  
Near Future ◽  
Polarization Phase

Metasurfaces, kinds of planar ultrathin metamaterials, are able to modify the polarization, phase, and amplitude of physical fields of optical light by designed periodic subwavelength structures, attracting great interest in recent years. Based on the different type of the material, optical metasurfaces can be separated in two categories by the materials: one is metal and the other is dielectric. Metal metasurfaces rely on the surface plasma oscillations of subwavelength metal particles. Nevertheless, the loss caused by the metal structures has been a trouble, especially for devices working in transmit modes. The dielectric metasurfaces are based on the Faraday-Tyndall scattering of high-index dielectric light scattering particles. By reasonably designing the relevant parameters of the unit structure such as the size, direction, and shape, different functions of metasurfaces can realize and bring a wide range of applications. This article focuses on the metasurface concepts such as anomalous reflections and refractions and the working principle of different types of metasurfaces. Here, we briefly review the progress in developing optical over past few years and look into the near future.

scholarly journals Addressing Challenges of Urban Water Management in Chinese Sponge Cities via Nature-Based Solutions

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2788
Author(s):  
Yunfei Qi ◽  
Faith Ka Shun Chan ◽  
Colin Thorne ◽  
Emily O’Donnell ◽  
Carlotta Quagliolo ◽  
...  
Keyword(s):  
Flood Risk ◽  
Urban Water ◽  
Operating Life ◽  
Rapid Urbanization ◽  
Urban Flood ◽  
Natural Processes ◽  
Trade Offs ◽  
Wide Range ◽  
Fit For Purpose ◽  
Competing Priorities

Urban flooding has become a serious issue in most Chinese cities due to rapid urbanization and extreme weather, as evidenced by severe events in Beijing (2012), Ningbo (2013), Guangzhou (2015), Wuhan (2016), Shenzhen (2019), and Chongqing (2020). The Chinese “Sponge City Program” (SCP), initiated in 2013 and adopted by 30 pilot cities, is developing solutions to manage urban flood risk, purify stormwater, and provide water storage opportunities for future usage. Emerging challenges to the continued implementation of Sponge Cities include (1) uncertainty regarding future hydrological conditions related to climate change projections, which complicates urban planning and designing infrastructure that will be fit for purpose over its intended operating life, and (2) the competing priorities of stakeholders and their reluctance to make trade-offs, which obstruct future investment in the SCP. Nature-Based Solutions (NBS) is an umbrella concept that emerged from Europe, which encourages the holistic idea of considering wider options that combine “Blue–Green” practices with traditional engineering to deliver “integrated systems of Blue–Green–Grey infrastructure”. NBS includes interventions making use of natural processes and ecosystem services for functional purposes, and this could help to improve current pilot SCP practices. This manuscript reviews the development of the SCP, focusing on its construction and design aspects, and discusses how approaches using NBS could be included in the SCP to tackle not only urban water challenges but also a wide range of social and environmental challenges, including human health, pollution (via nutrients, metals, sediments, plastics, etc.), flood risk, and biodiversity.

Large Diameter Pipeline PLEM Design for Remote, Arctic Application

2013 ◽  
Author(s):  
Jeroen Timmermans ◽  
Ian Luff ◽  
Nicholas Long
Keyword(s):  
North Sea ◽  
Large Diameter ◽  
Lessons Learned ◽  
Cost Driver ◽  
Pile Foundations ◽  
The Arctic ◽  
Normal Operation ◽  
Operating Life ◽  
Wide Range

While subsea production template and manifold designs have come to be dominated by standardized solutions tailored for specific hardware, the design of Pipeline End Manifolds (PLEM) remains largely project-specific. Nevertheless, some trends in PLEM design for large-diameter pipelines in moderate water depths have emerged in the past years in the North Sea and elsewhere; namely, large stand-alone structures on suction pile foundations with diverless spoolpiece tie-ins. This arrangement has proven successful on numerous projects; however, the move to remote arctic fields of significant production capacity and long design life introduces new design drivers that warrant a “fresh approach” to PLEM design. The developments currently being considered for the arctic will have to deal with: - Remote location making mobilization of installation assets a significant cost driver such that separate installation of pipeline and PLEM is relatively unattractive - Harsh conditions and short weather windows for installation favoring designs that reduce the number of separate installation steps and vessels - Poorer access for maintenance and repair during the operating life favoring designs that are modular and that allow recovery of critical components using the smallest possible intervention vessels. When combined with envisioned field production lives of 40 to 50 years, this means a very different set of design drivers will apply to the PLEM design. This paper presents an alternative PLEM design developed to overcome these challenges by: - Integrating of the PLEM with the pipeline to work around current industry limitations for large diameter diverless tie-in connector systems and to minimize ROV rotated sealing surfaces subsea in normal operation, - Introducing plug technology to remove the critical dependence on long-term trouble-free performance of large bore valves, - Introducing driven pile foundations to reduce structure size, prevent long-term settlements and eliminate the need for separate pipeline support frames by maintaining the pipe centerline close to the mudline, - Modularizing the system such that key components (all remaining valves) can be retrieved without complete shutdown of flow and such that installation / intervention can be performed using a wide range of vessels, and - Incorporating lessons learned from the successful design of a North Sea vertical diverless pig launcher unit. This paper presents an overview of the alternative PLEM design and discusses the status of the technologies required.

scholarly journals Effect of indirect interband transitions on terahertz conductivity in “decorated” graphene bilayer heterostructures

2016 ◽  
Vol 55 (4) ◽  
Author(s):  
Victor Ryzhii ◽  
Taiichi Otsuji ◽  
Maxim Ryzhii ◽  
Vladimir Mitin ◽  
Michael S. Shur
Keyword(s):  
Population Inversion ◽  
Room Temperature ◽  
Metal Particles ◽  
Interband Transitions ◽  
Graphene Bilayer ◽  
Wide Range ◽  
The Creation ◽  
Terahertz Conductivity

We demonstrate that the indirect interband generation of photons in the optically or injection pumped graphene bilayer (GBL) heterostructures with an array of metal particles (GBLs “decorated” by metal particles) with population inversion can surpass their intraband (Drude) absorption. This can result in rather large absolute values of the negative dynamic terahertz (THz) conductivity in a wide range of frequencies at room temperature. This effect enables the creation of novel THz lasers based on the decorated GBLs.

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