Development of MEMS MOS gas sensors with CMOS compatible PECVD inter-metal passivation

Self Cite

Among the various chemoresistive gas sensing properties studied so far, the sensing response reproducibility, i.e., the capability to reproduce a device with the same sensing performance, has been poorly investigated. However, the reproducibility of the gas sensing performance is of fundamental importance for the employment of these devices in on-field applications, and to demonstrate the reliability of the process development. This sensor property became crucial for the preparation of medical diagnostic tools, in which the use of specific chemoresistive gas sensors along with a dedicated algorithm can be used for screening diseases. In this work, the reproducibility of SmFeO3 perovskite-based gas sensors has been investigated. A set of four SmFeO3 devices, obtained from the same screen-printing deposition, have been tested in laboratory with both controlled concentrations of CO and biological fecal samples. The fecal samples tested were employed in the clinical validation protocol of a prototype for non-invasive colorectal cancer prescreening. Sensors showed a high reproducibility degree, with an error lower than 2% of the response value for the test with CO and lower than 6% for fecal samples. Finally, the reproducibility of the SmFeO3 sensor response and recovery times for fecal samples was also evaluated.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanostructured SmFeO3 Gas Sensors: Investigation of the Gas Sensing Performance Reproducibility for Colorectal Cancer Screening

Gaiardo

Zonta

Gherardi

et al. 2020

Self Cite

“…The role of the substrate is significant for the proper device operation, because it not only acts as a mechanical support of the sensing material but, also, it hosts the heater and electrodes. The former allows the heating of the sensing material at its best working temperature, whereas the latter are needed to read the electrical resistance of the sensing material [ 31 ]. The technical requirements for the optimal operation of a substrate are the high mechanical and thermal stability, low chemical reactivity, low power consumption and suitability for large-scale production.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a Low-Power Chemoresistive Gas Sensor: Predictive Thermal Modelling and Mechanical Failure Analysis

Gaiardo

Novel

Scattolo

et al. 2021

Self Cite

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.

“…In recent years, researchers have prepared a large number of MOS gas sensors around ethanol gas including ZnO gas sensors [ 24 ], Fe 2 O 3 gas sensors [ 25 ], In 2 O 3 gas sensors [ 26 ], SnO 2 gas sensors [ 27 ], and so on. However, a traditional single MOS gas sensor has certain limitations such as high detection threshold, poor selectivity, low response value, high operating temperature, etc., which limit the application of a MOS gas sensor in a real environment [ 28 , 29 ]. Therefore, a variety of research schemes for improving MOS gas sensors have been proposed including noble metal modification [ 30 ], construction of heterojunction [ 31 ], optimizing microstructure [ 32 ], etc.…”

Section: Introductionmentioning

confidence: 99%

Ethanol Sensors Based on Porous In2O3 Nanosheet-Assembled Micro-Flowers

Qin

Yuan

Gao

et al. 2020

By controlling the hydrothermal time, porous In2O3 nanosheet-assembled micro-flowers were successfully synthesized by a one-step method. The crystal structure, microstructure, and internal structure of the prepared samples were represented by an x-ray structure diffractometry, scanning electron microscopy, and transmission electron microscopy, respectively. The characterization results showed that when the hydrothermal time was 8 h, the In2O3 nano materials presented a flower-like structure assembled by In2O3 porous nanosheets. After successfully preparing the In2O3 gas sensor, the gas sensing was fully studied. The results show that the In2O3 gas sensor had an excellent gas sensing response to ethanol, and the material prepared under 8 h hydrothermal conditions had the best gas sensing property. At the optimum working temperature of 270 °C, the highest response value could reach 66, with a response time of 12.4 s and recovery time of 10.4 s, respectively. In addition, the prepared In2O3 gas sensor had a wide detection range for ethanol concentration, and still had obvious response for 500 ppb ethanol. Furthermore, the gas sensing mechanism of In2O3 micro-flowers was also studied in detail.