A high temperature and low power SOI CMOS MEMS based thermal conductivity gas sensor

Sarfraz, Sohab; Kumar, R. Vasant; Udrea, F.

doi:10.1109/smicnd.2013.6688086

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…The first point of optimisation comes from the heated element itself, which is directly accountable for the heat transfer magnitude between the sensor and the measurand. Firstly, various materials have been used such as platinum [ 100 ], tungsten [ 5 , 101 , 102 ], polysilicon [ 64 , 103 ], carbon nanotubes [ 104 ] and other carbon materials [ 105 ], including a gold-coated carbon nanoribbon-based heater [ 106 ]. It should be noted that carbon nanotubes must be locally grown onto an already fabricated device, rendering this design not CMOS compatible and hence not yet a commercially viable solution.…”

Section: Recent Developmentsmentioning

confidence: 99%

Micromachined Thermal Gas Sensors—A Review

Gardner

Udrea

2023

Sensors

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In recent years, there has been a growing desire to monitor and control harmful substances arising from industrial processes that impact upon our health and quality of life. This has led to a large market demand for gas sensors, which are commonly based on sensors that rely upon a chemical reaction with the target analyte. In contrast, thermal conductivity detectors are physical sensors that detect gases through a change in their thermal conductivity. Thermal conductivity gas sensors offer several advantages over their chemical (reactive) counterparts that include higher reproducibility, better stability, lower cost, lower power consumption, simpler construction, faster response time, longer lifetime, wide dynamic range, and smaller footprint. It is for these reasons, despite a poor selectivity, that they are gaining renewed interest after recent developments in MEMS-based silicon sensors allowing CMOS integration and smart application within the emerging Internet of Things (IoT). This timely review focuses on the state-of-the-art in thermal conductivity sensors; it contains a general introduction, theory of operation, interface electronics, use in commercial applications, and recent research developments. In addition, both steady-state and transient methods of operation are discussed with their relative advantages and disadvantages presented. Finally, some of recent innovations in thermal conductivity gas sensors are explored.

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Section: Recent Developmentsmentioning

confidence: 99%

Micromachined Thermal Gas Sensors—A Review

Gardner

Udrea

2023

Sensors

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A ratiometric readout circuit for thermal-conductivity-based resistive gas sensors

Cai

Veldhoven

Falepin

et al. 2015

ESSCIRC Conference 2015 - 41st European Solid-State Circuits Conference (ESSCIRC)

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A Ratiometric Readout Circuit for Thermal-Conductivity-Based Resistive CO₂Sensors

Cai

Veldhoven

Falepin

et al. 2016

IEEE J. Solid-State Circuits

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This paper reports a readout circuit for a resistive CO 2 sensor, which operates by measuring the CO 2-dependent thermal conductivity of air. A suspended hot-wire transducer, which acts both as a resistive heater and temperature sensor, exhibits a CO 2-dependent heat loss to the surrounding air, allowing CO 2 concentration to be derived from its temperature rise and power dissipation. The circuit employs a dual-mode incremental delta-sigma ADC to digitize these parameters relative to those of an identical, but isolated, reference transducer. This ratiometric approach results in a measurement that does not require precision voltage or power references. The readout circuit uses dynamically-swapped transducer pairs to cancel their baseline-resistance, so as to relax the required dynamic range of the ADC. In addition, dynamic element matching (DEM) is used to bias the transducer pairs at an accurate current ratio, making the measurement insensitive to the precise value of the bias current. The readout circuit has been implemented in a standard 0.16 µm CMOS technology. With commercial resistive micro-heaters, a CO 2 sensing resolution of about 200 ppm (1σ) was achieved in a measurement time of 30 s.

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A high temperature and low power SOI CMOS MEMS based thermal conductivity gas sensor

Cited by 3 publications

References 5 publications

Micromachined Thermal Gas Sensors—A Review

Micromachined Thermal Gas Sensors—A Review

A ratiometric readout circuit for thermal-conductivity-based resistive gas sensors

A Ratiometric Readout Circuit for Thermal-Conductivity-Based Resistive CO₂Sensors

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A high temperature and low power SOI CMOS MEMS based thermal conductivity gas sensor

Cited by 3 publications

References 5 publications

Micromachined Thermal Gas Sensors—A Review

Micromachined Thermal Gas Sensors—A Review

A ratiometric readout circuit for thermal-conductivity-based resistive gas sensors

A Ratiometric Readout Circuit for Thermal-Conductivity-Based Resistive CO2Sensors

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A Ratiometric Readout Circuit for Thermal-Conductivity-Based Resistive CO₂Sensors