scholarly journals A Novel Miniature and Selective CMOS Gas Sensor for Gas Mixture Analysis—Part 2: Emphasis on Physical Aspects

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 587
Author(s):  
Moshe Avraham ◽  
Sara Stolyarova ◽  
Tanya Blank ◽  
Sharon Bar-Lev ◽  
Gady Golan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Gas Sensor ◽  
Catalytic Reaction ◽  
Analytical Models ◽  
Gas Mixture ◽  
Thermal Sensor ◽  
Catalytic Layer ◽  
Sensing Element ◽  
Hot Plate ◽  
Good Agreement

This is a second part of the paper presenting a miniature, combustion-type gas sensor (dubbed GMOS) based on a novel thermal sensor (dubbed TMOS). The TMOS is a micromachined CMOS-SOI transistor, which acts as the sensing element and is integrated with a catalytic reaction plate, where ignition of the gas takes place. Part 1 focused on the chemical and technological aspects of the sensor. In part 2, the emphasis is on the physical aspects of the reaction micro-hot plate on which the catalytic layer is deposited. The three main challenges in designing the hot plate are addressed: (i) How to design a hot plate operating in air, with a low thermal conductivity; (ii) how to measure the temperature of the hot plate during operation; (iii) how to reduce the total consumed power during operation. Reported simulated as well as analytical models and measured results are in good agreement.

scholarly journals Novel Miniature and Selective Combustion-Type CMOS Gas Sensor for Gas-Mixture Analysis—Part 1: Emphasis on Chemical Aspects

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 345 ◽  
Author(s):  
Dima Shlenkevitch ◽  
Sara Stolyarova ◽  
Tanya Blank ◽  
Igor Brouk ◽  
Yael Nemirovsky
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Low Cost ◽  
Gas Mixture ◽  
Catalytic Layer ◽  
Pt Nanoparticle ◽  
Wafer Level ◽  
Sensing Element ◽  
Deposition Techniques ◽  
Nanoparticle Catalyst

There is an ongoing effort to fabricate miniature, low cost, sensitive, and selective gas sensors for domestic and industrial uses. This paper presents a miniature combustion-type gas sensor (GMOS) based on a thermal sensor, where a micromachined CMOS–SOI transistor integrated with a catalytic reaction plate acts as a sensing element. This study emphasizes GMOS performance modeling, technological aspects, and sensing-selectivity issues. Two deposition techniques of a Pt catalytic layer suitable for wafer-level processing were compared, magnetron sputtering and nanoparticle inkjet printing. Both techniques have been useful for the fabrication of GMOS sensor, with good sensitivity to ethanol and acetone in the air. However, a printed Pt nanoparticle catalyst provides almost twice as much sensitivity as compared to that of the sputtered catalyst. Moreover, sensing selectivity in the ethanol/acetone gas mixture was demonstrated for the GMOS with a Pt nanoparticle catalyst. These advantages of GMOS allow for the fabrication of a low-cost gas sensor that requires a low power, and make it a promising technology for future smartphones, wearables, and Internet of Things (IoT) applications.

A LARGE-SCALE THERMAL CONDUCTANCE APPARATUS USED FOR THE TESTING OF BUILDING MATERIALS

1939 ◽  
Vol 17a (8) ◽  
pp. 164-177
Author(s):  
J. D. Babbitt
Keyword(s):  
Thermal Conductivity ◽  
Large Scale ◽  
Building Materials ◽  
Thermal Conductance ◽  
Short Description ◽  
Hot Plate ◽  
Good Agreement

A short description and discussion are given of a thermal conductance apparatus of the guarded hot-box type used by the National Research Laboratories, Ottawa, for the measurement of the thermal conductivity of building materials. Results obtained with this apparatus are compared with hot-plate measurements on the same materials and indicate good agreement between the two methods.

scholarly journals Reducing Food Waste with a Tiny CMOS-MEMS Gas Sensor, Dubbed GMOS

2020 ◽  
Vol 2 (1) ◽  
pp. 36
Author(s):  
Dima Shlenkevitch ◽  
Sara Stolyarova ◽  
Tanya Blank ◽  
Igor Brouk ◽  
Yossi Levi ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Low Cost ◽  
Catalytic Layer ◽  
Sensing Element ◽  
Detection Systems ◽  
Current Voltage ◽  
Mems Technology ◽  
Cmos Mems ◽  
Sensor Temperature ◽  
Different Gases

We present a tiny combustion-type gas sensor (named GMOS) fabricated using standard CMOS-SOI-MEMS technology. It is a low-cost thermal sensor with an embedded heater, catalytic layer and suspended transistor as a sensing element. The sensor principle relies on the combustion reaction of the gas that takes place on the catalytic layer. The exothermic combustion leads to a sensor temperature increase, which modifies the transistor current-voltage characteristics. The GMOS is useful for detecting different gases, such as ethanol, acetone and especially ethylene, as well as their mixtures. The sensor demonstrates an excellent sensitivity to ethylene of 40 mV/ppm and selective ethylene detection using nanoparticle catalytic layers of Pt, as well as TiO2. Along with its low energy consumption, GMOS is a promising technology for low-cost ethylene detection systems at different stages in the food supply chain, and it may help reduce global fruit and vegetable loss and waste.

Improvements to the Guarded Hot Plate Apparatus to Determine Thermal Conductivity

2017 ◽  
Author(s):  
Gabriel Souza ◽  
Luís Felipe dos Santos Carollo ◽  
Sandro Metrevelle Marcondes de Lima e Silva
Keyword(s):  
Thermal Conductivity ◽  
Hot Plate ◽  
Guarded Hot Plate ◽  
Plate Apparatus

scholarly journals Thermal ignition of a combustible over an inclined hot plate

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Salaika Parvin ◽  
Nepal Chandra Roy ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Mixed Convection ◽  
Convection Flow ◽  
Physical Parameters ◽  
Thermal Ignition ◽  
Mixed Convection Flow ◽  
Flow Properties ◽  
Continuous Transformation ◽  
Hot Plate ◽  
Ignition Characteristics ◽  
Good Agreement

AbstractIn this study, the ignition characteristics and the flow properties of the mixed convection flow are presented. Detailed formulations of the forced, natural and mixed convection problems have been discussed. In order to avoid inconvenient switch between the forced and natural convection we introduce a continuous transformation in the mixed convection. We make a comparison between these situations which reveal a good agreement. For mixed convection flow, the ignition distance is explicitly expressed as a function of the Prandtl number, reaction parameter and wall temperature. It has been observed that owing to the increase of the aforesaid parameters, the thermal ignition distance is reduced. Numerical results are illustrated for velocity, temperature, and concentration for different physical parameters. Furthermore, the development of combustion is presented by using streamlines, isotherms and isolines of fuel and oxidizer.

Sticky thermoelectric materials for flexible thermoelectric modules to capture low-temperature waste heat

MRS Advances ◽  
2020 ◽  
Vol 5 (10) ◽  
pp. 481-487 ◽  
Author(s):  
Norifusa Satoh ◽  
Masaji Otsuka ◽  
Yasuaki Sakurai ◽  
Takeshi Asami ◽  
Yoshitsugu Goto ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Waste Heat ◽  
Air Cooling ◽  
Conductive Adhesives ◽  
Hot Plate ◽  
Low Thermal Conductivity ◽  
Te Modules ◽  
P Type ◽  
Flexible Thermoelectric

ABSTRACTWe examined a working hypothesis of sticky thermoelectric (TE) materials, which is inversely designed to mass-produce flexible TE sheets with lamination or roll-to-roll processes without electric conductive adhesives. Herein, we prepared p-type and n-type sticky TE materials via mixing antimony and bismuth powders with low-volatilizable organic solvents to achieve a low thermal conductivity. Since the sticky TE materials are additionally injected into punched polymer sheets to contact with the upper and bottom electrodes in the fabrication process, the sticky TE modules of ca. 2.4 mm in thickness maintained temperature differences of ca. 10°C and 40°C on a hot plate of 40 °C and 120°C under a natural-air cooling condition with a fin. In the single-cell resistance analysis, we found that 75∼150-µm bismuth powder shows lower resistance than the smaller-sized one due to the fewer number of particle-particle interfaces in the electric pass between the upper and bottom electrodes. After adjusting the printed wiring pattern for the upper and bottom electrodes, we achieved 42 mV on a hot plate (120°C) with the 6 x 6 module having 212 Ω in the total resistance. In addition to the possibility of mass production at a reasonable cost, the sticky TE materials provide a low thermal conductivity for flexible TE modules to capture low-temperature waste heat under natural-air cooling conditions with fins for the purpose of energy harvesting.

A logarithmic multi-parameter model using gas sensor main and cross sensitivities to estimate gas concentrations in a gas mixture for SnO2 gas sensors

2007 ◽  
Vol 123 (2) ◽  
pp. 1064-1070 ◽  
Author(s):  
A. Chaiyboun ◽  
R. Traute ◽  
T. Haas ◽  
O. Kiesewetter ◽  
T. Doll
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Gas Mixture

The Estimation of Thermal Conductivity for Alumina-Epoxy Composite Material with High Filling Volume Fraction

2014 ◽  
Vol 918 ◽  
pp. 21-26
Author(s):  
Chen Kang Huang ◽  
Yun Ching Leong
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Composite Materials ◽  
Physical Model ◽  
Electron Scattering ◽  
Volume Fraction ◽  
Epoxy Composite ◽  
The Matrix ◽  
Transport Theorem ◽  
Good Agreement

In this study, the transport theorem of phonons and electrons is utilized to create a model to predict the thermal conductivity of composite materials. By observing or assuming the dopant displacement in the matrix, a physical model between dopant and matrix can be built, and the composite material can be divided into several regions. In each region, the phonon or electron scattering caused by boundaries, impurities, or U-processes was taken into account to calculate the thermal conductivity. The model is then used to predict the composite thermal conductivity for several composite materials. It shows a pretty good agreement with previous studies in literatures. Based on the model, some discussions about dopant size and volume fraction are also made.

scholarly journals Thermal conductivity of unsaturated clay-rocks

2010 ◽  
Vol 14 (1) ◽  
pp. 91-98 ◽  
Author(s):  
D. Jougnot ◽  
A. Revil
Keyword(s):  
Thermal Conductivity ◽  
Porous Material ◽  
Solid Phase ◽  
Model Parameters ◽  
Electrical Parameters ◽  
New Model ◽  
Unsaturated Clay ◽  
Unsaturated Porous Material ◽  
Clay Rocks ◽  
Good Agreement

Abstract. The parameters used to describe the electrical conductivity of a porous material can be used to describe also its thermal conductivity. A new relationship is developed to connect the thermal conductivity of an unsaturated porous material to the thermal conductivity of the different phases of the composite, and two electrical parameters called the first and second Archie's exponents. A good agreement is obtained between the new model and thermal conductivity measurements performed using packs of glass beads and core samples of the Callovo-Oxfordian clay-rocks at different saturations of the water phase. We showed that the three model parameters optimised to fit the new model against experimental data (namely the thermal conductivity of the solid phase and the two Archie's exponents) are consistent with independent estimates. We also observed that the anisotropy of the effective thermal conductivity of the Callovo-Oxfordian clay-rock was mainly due to the anisotropy of the thermal conductivity of the solid phase.

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