MEMS Gas-Sensor Array for Monitoring the Perceived Car-Cabin Air Quality

Abstract

Microelectromechanical-system (MEMS) metaloxide gas sensors have reached a mature stage, which makes mass market applications in the automotive area possible. In contrast to the already established flap-control system, which controls the access of (combustion) gases from outside the vehicle to the car cabin, the system studied here detects odor events created within the car cabin. The events under study have been cigarette smoke, fast-food odor, manure, and bioeffluents (flatulence). As the reference cannot be a "simple analytical measurement," a human test panel for assessing the hedonic impression on a scale from 0 to 5 is used as reference. The technical system is a MEMS metal-oxide-sensor array consisting of three different sensors. The data-evaluation approach used here is combining the human-sensory data and the MEMS sensor data. The task is performed by the combination of two independent algorithms, where one is related to the normalized conductance and the other to signal variance. Using a combined approach has the advantage that "false" events are suppressed. After the algorithm was successfully transferred onto a microcontroller, real-life data were recorded and classified. Several practical examples are given in this paper. The overall gas-sensor system reaches good accordance with the human-sensory impression, which is represented by air quality levels. This enables the design of a demand-controlled ventilation system. Index Terms-Air quality, gas sensor, heating ventilation and air conditioning (HVAC), low power, microelectromechanical systems (MEMS), sensor array.

Electronic Nose: Current Status and Future Trends

“…107 Applications where the odor impression does not come to the fore are the determination of single solvents or mixtures of them, 108 the identification of microorganisms such as bacteria and fungi, 109 the detection of leaking of refrigerant gas, 110 and the differentiation between automotive fuels. 111,112 Very practical examples are the detection of smoke compounds, 113 the control of automotive ventilation, 114,115 and the determination of indoor air quality. [116][117][118][119] For headspace measurement of water samples, both very specific and more general cases were considered.…”

In Situ and Operando Spectroscopy for Assessing Mechanisms of Gas Sensing

“…[83] (thickness of SiO 2 layer: 300 nm; pSi = p-doped silicon, V GS = gate-to-source voltage, V SD = source-to-drain voltage); c) micromachined sensing element; top: side view, left bottom: 3D view, right bottom: microscopy image of the sensor. [84] A. Gurlo and R. Riedel Reviews 3830 www.angewandte.org…”

Gas Sensors for Monitoring Air Pollution

“…Recently, gas sensor array for monitoring the perceived car-cabin air quality was reported [34,77]. The technological process in microelectromechanical system (MEMS) metal oxide gas sensors in terms of stability and reproducibility has promoted the technology for mass market applications.…”