Sensing of gas molecules is critical to environmental monitoring, control of chemical processes, agricultural, and medical applications In particular, the detection of industrial toxic gases such as CO, NO x , and NH 3 is very important for many industries Metal oxides have been widely studied for the sensitivity of their properties to gases even though they do have some limitations Recently, graphene has been considered as a promising material for gas sensing since its electronic properties are strongly affected by the adsorption of foreign molecules Intrinsic graphene has high sensitivity at low gas concentrations; but the sensor selectivity is poor which limits its use in many practical applications Hence, hybrid architectures formed by blending of nanoparticles of metal–oxides with graphene or its derivatives have been explored by several researchers which showed improved gas sensing ability, especially the sensitivity and selectivity at room temperature Here we review the state of the art of gas sensors based on graphene and metal oxide hybrid nanostructures for detection of various common toxic gases

Graphene–metal oxide nanohybrids for toxic gas sensor: A review

Instructions This exam consists of 50 questions. You may write on the exam itself, but be sure to answer all your questions on a “Scantron” sheet with a #2 pencil. For each question there is one response that is the best response. You must select the one best response to receive credit for each question. If you select more than one response for a question, then you will receive no credit for that question.

人体の解剖生理学 = Human anatomy & physiology

This article presents the fabrication and characterization of novel tattoo-based solid-contact ion-selective electrodes (ISEs) for non-invasive potentiometric monitoring of epidermal pH levels. The new fabrication approach combines commercially available temporary transfer tattoo paper with conventional screen printing and solid-contact polymer ISE methodologies. The resulting tattoo-based potentiometric sensors exhibit rapid and sensitive response to a wide range of pH changes with no carry-over effects. Furthermore, the tattoo ISE sensors endure repetitive mechanical deformation, which is a key requirement of wearable and epidermal sensors. The flexible and conformal nature of the tattoo sensors enable them to be mounted on nearly any exposed skin surface for real-time pH monitoring of the human perspiration, as illustrated from the response during a strenuous physical activity. The resulting tattoo-based ISE sensors offer considerable promise as wearable potentiometric sensors suitable for diverse applications.

Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring

Poly (ionic liquid)s attracted enormous attention as adsorbents for the CO2 separation from natural gas. Hence, in this work poly (1-butyl-3-vinylimidazolium bromide), P[VBIm][Br], poly (1-butyl-3-vinylimidazolium thiocyanate), P[VBIm][SCN], and poly (1-butyl-3-vinylimidazolium tetrafluoroborate), P[VBIm][BF4] were synthesized and evaluated their CO2 adsorption performance. The synthesized poly(ionic liquid)s were characterized by 1H NMR, FT-IR spectroscopy, and differential scanning calorimetery (DSC) analysis. The CO2 adsorption was studied at various temperatures and pressures by quartz crystal microbalance (QCM) and experimental data were correlated by a model of dual-mode. The Henry and Langmuir contributions in CO2 adsorption were evaluated. The obtained thermodynamics and kinetics parameters of CO2 adsorption reveal that CO2 adsorption has an exothermic and physisorption nature. Also, density functional theory (DFT) computations were done in order to assess interactions between poly(ionic liquid)s with CO2 gas. DFT computations corroborated that interaction of P[VBIm][SCN] with CO2 is stronger than those of other poly(ionic liquid)s.

经Co

Conducting polymer-based electrochemical biosensors for neurotransmitters: A review

An electronic nose-based assistive diagnostic prototype for lung cancer detection with conformal prediction

Flowerlike nanometer scaled tin oxide (nano-SnO2) was synthesized by a novel and green method without annealing. Accordingly, a dimethyl methylphosphonate (DMMP) gas sensor based on a quartz crystal microbalance was fabricated and studied. According to the experimental results, the sensor with the flowerlike nano-SnO2 sensing film working at room temperature exhibited good sensitivity and selectivity as well as a rapid response to DMMP. An environmentally friendly idea to synthesize material in a green way and fabricate sensors to detect harmful or toxic gases was realized.

https://iopscience.iop.org/article/10.1088/0957-0233/22/4/045203/pdf

Synthesis of flowerlike nano-SnO2 and a study of its gas sensing response

This paper introduces an optimized deep convolutional neural network (DCNN) using special banded 1D kernels at the convolutional and the pooling layers adapted for electronic nose (E-nose) data. It is used to classify multiple types of Chinese herbal medicine. The optimized DCNN network is composed of 5 special convolutional layers with 1D convolutional kernels, 2 special pooling layers with 1D size, 1 fully connected layer and 1 Softmax layer. Results show that the optimized DCNN achieves the best accuracy of 87.56%, outperforming the 81.67% from the second-best classifier DCNN. The optimized DCNN extracts features from E-nose data faster and better than common DCNN. This paper also proposes an insight of applying DCNN to small-scale and E-nose data.

An optimized deep convolutional neural network for dendrobium classification based on electronic nose

Nonenzymatic all-solid-state coated wire electrode for acetylcholine determination in vitro.

Highly sensitive chemical warfare agents (CWAs) detection is demanded against the usage of the CWAs for war or terrorism aims. A dimethyl methylphosphonate (DMMP), simulant for sarin, monitoring sensor based on a homemade wireless-electrodeless quartz crystal microbalance with dissipation (QCM-D) was developed. With this noncontact configuration, deterioration of the sensing ability cause by the electrodes and drilling on the gas chamber for wire lead was avoided. Nano-structured hollow ball-like indium oxide (In2O3) was synthesized using a facile hydrothermal method and then decorated with cubic gold particles (In2O3-Au). Both of them were applied as the sensing films to detect DMMP. The In2O3-Au based QCM-D sensor exhibited 2.1 Hz/ppm to DMMP range from 5 ppm to 50 ppm, which was 400% higher compared to the undecorated one. Moreover, with the simultaneously monitored dissipation value, desorption processes of DMMP was further investigated and the overshoot that appear in some researches was explained in terms of visco-elastic variations in mechanical stiffness. The results suggest that the wireless-electrodeless QCM-D could be a promising strategy for observation of materials under dynamic conditions.

You Wang

Papers

An electronic nose-based assistive diagnostic prototype for lung cancer detection with conformal prediction

Synthesis of flowerlike nano-SnO2 and a study of its gas sensing response

An optimized deep convolutional neural network for dendrobium classification based on electronic nose

Nonenzymatic all-solid-state coated wire electrode for acetylcholine determination in vitro.

A wireless-electrodeless quartz crystal microbalance with dissipation DMMP sensor