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Your search keyword '"Vereshchagina, E."' showing total 2 results
Start Over Author "Vereshchagina, E." Topic polysilicon
2 results on '"Vereshchagina, E."'

1. Low power micro-calorimetric sensors for analysis of gaseous samples.

Author

Vereshchagina, E., Tiggelaar, R.M., Sanders, R.G.P., Wolters, R.A.M., and Gardeniers, J.G.E.

Subjects
*SILICON, *MICROCALORIMETRY, *CHEMICAL detectors, *FINITE element method, *MICROFABRICATION
Abstract

This work discusses the design, finite element method modeling (FEM), fabrication and characterization of a silicon-based, catalytic micro calorimetric sensor. The sensing area is comprised of two titanium silicide (TiSi 2 ) – polysilicon (poly-Si) resistive temperature sensors symmetrically positioned relative to a poly-Si heater on which an oxidation promoting catalyst is deposited. The resistive structures are located on a suspended, thereby, thermally isolating, low mechanical stress membrane and integrated into a glass flow channel. The micro-calorimetric sensor is applied for measuring propane and hydrogen concentrations in air. An approach to optimization of thermal and fluidic design of the microsensor is presented based on developed models: (i) a 3D thermo-electric analysis of the suspended heater and (ii) a 2D thermo-chemical analysis of the catalytic oxidation of propane in the flow channel. Influence of the design and material of the membrane on the power consumption and temperature distribution across the sensing area are analyzed. A relationship between the thermal design of the sensor, reaction conditions and its operation as a thermal actuator and sensor of reaction heats are discussed. Various thermo-electrical characterizations (electrical, infrared surface imaging and transient thermal response measurements) in the context of microcalorimetric sensing are performed. Microsensors with a 50 μm × 50 μm sensing area consume ca. 12 mW at an operational temperature of 350 °C. Thermal imaging with an infrared camera indicates local heating with a temperature gradient across the active area estimated to be 4 °C μm −1 (at ca. 500 °C). The heating and cooling times are found to be ca. 1 and 8 ms, respectively. Temperature vs. power curves are determined for both stationary and constant flow conditions of various gases. Based on the experimental and modeling results we envision that these microsensors can be successfully used for calorimetric sensing and analysis of gaseous samples. [ABSTRACT FROM AUTHOR]

Published
2015
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2. Development Of Hot Surface Polysilicon-Based Chemical Sensor And Actuator With Integrated Catalytic Micropatterns For Gas Sensing Applications.

Author

Vereshchagina, E. and Gardeniers, J. G. E.

Subjects
*CHEMICAL detectors, *SURFACES (Technology), *MICROREACTORS, *ORGANIC chemistry, *ORGANIC compounds
Abstract

Over the last twenty years, we have followed a rapid expansion in the development of chemical sensors and microreactors for detection and analysis of volatile organic compounds. However, for many of the developed gas sensors poor sensitivity and selectivity, and high-power consumption remain among one of the main drawbacks. One promising approach to increase selectivity at lower power consumption is calorimetric sensing, performed in a pulsed regime and using specific catalytic materials. In this work, we study kinetics of various catalytic oxidation reactions using micromachined hot surface polysilicon-based sensor containing sensitive and selective catalysts. The sensor acts as both thermal actuator of chemical and biochemical reactions on hot-surfaces and detector of heats (enthalpies) associated with these reactions. Using novel deposition techniques we integrated selective catalysts in an array of hot plates such that they can be thermally actuated and sensed individually. This allows selective detection and analysis of dangerous gas compounds in a mixture, specifically hydrocarbons at concentrations down to low ppm level. In this contribution we compare various techniques for the local immobilization of catalytic material on hot spots of the sensor in terms of process compatibility, mechanical stress, stability and cost. [ABSTRACT FROM AUTHOR]

Published
2009
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