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Perspectives for Electronic Nose Technology in Green Analytical Chemistry
Published in Neha Kanwar Rawat, Iuliana Stoica, A. K. Haghi, Green Polymer Chemistry and Composites, 2021
T. Sonamani. Singh, Priyanka Singh, R. D. S. Yadava
Initially, the eNose architecture was visualized to be fully analogous to the biological nose as shown schematically in Figure 10.1. It consists of four basic subparts: air sampler, chemical sensors array, electrical signal conditioning and data acquisition unit, and data processing or pattern recognition unit. The air sampler is analogous to inhalation that brings odorant molecules in contact with the nasal epithelium. The epithelium contains several types of odorant receptors located on olfactory receptor neurons; each receptor type can sense a limited number of odorants. When activated by odorant molecules, the receptor neurons send signals directly to the olfactory bulb where the signals received from each type of receptor neurons converge to separate nodes (called glomeruli). The cumulative responses at nodes fire mitral cells, which transmit signals as response patterns to cortex part in brain for odor recognition.64 In an eNose system, the olfactory receptor neurons are replaced by selective chemical sensors array where individual sensors need not be highly specific rather respond to limited number of chemical analytes. We can call it chemical selectivity spectrum. The selectivity spectra of the sensors in array may overlap but must be centered on different chemicals in the target sample. The processing in olfactory bulb involves some filtering and reinforcement of received signals. This is done by signal conditioning part in eNose. The convergence of signals to different mitral cells and firing is the data preprocessing, feature extraction, and classification parts in the pattern recognition system. The set of outputs from mitral cells or classifier is uniquely encoded odor identity. The identification or decision activity in the brain is based on the prior experience. The brain responds to stimuli from the olfactory bulb and takes a decision about the identity and strength of the inhaled odor. This is accomplished by training the eNose in laboratory by exposing to various samples of known identity and concentration.65
Biological function simulation in neuromorphic devices: from synapse and neuron to behavior
Published in Science and Technology of Advanced Materials, 2023
Hui Chen, Huilin Li, Ting Ma, Shuangshuang Han, Qiuping Zhao
Nowadays, gas sensor is increasingly important in our life for gas monitoring, food quality and healthcare applications such as breath based early diagnosis of diseases [139–141]. With the development of artificial intelligence, more and more gas sensors are integrated with memristors/neuromorphic devices to simulate human olfactory system. Li et al. [142] used 2D covalent organic framework (COF) film to develop a gas artificial synapse that can identify the alcohol atmospheres. Inspired by camel noses, Huang et al. [143] developed a highly sensitive and ultradurable neuromorphic capacitive humidity sensor that exhibited a robust capability to discriminate moisture from other volatile compounds. In the biological olfactory sensing system (Figure 10(b-i)), when the gas is sucked up into the nose, the odorant stimulates the olfactory receptors so that the chemical reactions between them trigger electrical signals as an output. These electrical signals are then transmitted to the olfactory bulb through glomeruli. Mitral cells and interneurons in the olfactory bulb can preprocess and transmit the electrical signals into the brain olfactory cortex to identify the odor.
Pollution characteristics, mechanism of toxicity and health effects of the ultrafine particles in the indoor environment: Current status and future perspectives
Published in Critical Reviews in Environmental Science and Technology, 2022
Muhammad Ubaid Ali, Siyi Lin, Balal Yousaf, Qumber Abbas, Mehr Ahmed Mujtaba Munir, Audil Rashid, Chunmiao Zheng, Xingxing Kuang, Ming Hung Wong
Long episode exposure to air pollutants may lead to direct translocation of UFPs into the central nervous system (CNS), where they can cause neuropathological effects through different pathways. However, the entry of UFPs might not lead directly into CNS, but it can exert negative impacts on CNS by generating soluble inflammatory mediators from primary entry systems and secondary deposition sites that lead to susceptibility for neuro-inflammation and neurodegeneration (Genc et al., 2012). A previous study revealed that after inhalation, the translocated UFPs can found in the brain within 4–24 h. The UFPs travel to the brain through the olfactory nerves from the nasal cavity. In animals, almost 20% of the UFPs deposited on olfactory mucosa were translocated to the olfactory bulb (Oberdörster et al., 2004). From the olfactory bulb, translocation may be through mitral cell axons that lead from the olfactory bulb to different parts of the brain such as the olfactory cortex, anterior olfactory nucleus, piriform cortex, hypothalamus and amygdala (Wang et al., 2007). In humans, the translocation pathways that can by-pass blood-brain barrier may more direct and the UFPs, not only translocate and effect neural tissue directly, but can also impact the autonomic function (Heusser et al., 2019; Tian et al., 2019). An increase in activity of the sympathetic nervous system was noticed due to a decrease in norepinephrine clearance after exposure to UFPs (Heusser et al., 2019). Small size and large surface areas enable UFPs to pass the barriers in the brain and lungs, and this ability explains the presence of UFPs in neurons and erythrocytes. As endothelial cells and erythrocytes are in close contact it can be a possible route for UFPs exchange between UFPs loaded erythrocytes and activated endothelial cells (Block & Caldero, 2009; Geiser et al., 2005).