Linking biological and artificial olfaction: biomimetic quartz crystal microbalance odor sensors

Biological olfaction is a powerful system enabling acquisition and processing of various chemical information from environment. Vast significance of the sense of smell is reflected in attempts to create instrumental techniques mimicking the biological system—artificial/machine olfaction. Following the biological systems, the artificial olfaction relies on arrays of gas sensors with broad specificities to odorants. Arguably, among available gas-sensing technologies, the most suitable choices for artificial olfaction are acoustic wave sensors, including quartz crystal microbalance (QCM) gas/odor sensors. The short review herein presents basic information on organization and principles of biological and artificial olfaction systems as well as several methods for fabrication of biomimetic or bioinspired (QCM) sensors for artificial olfaction. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于嵌入式的腊肉检测手持终端系统的研制

研究和实现基于嵌入式Raspberry Pi的手持式腊肉检测终端系统。利用计算机视觉和人工嗅觉分别采集腊肉的颜色或菌斑面积特征信息和挥发性气体值,将采集的数据经过GPRS传递给上位机,数据分析后将结果返回,实现对腊肉新鲜度的快速、便携检测。试验表明:该检测终端具有很好的精确度和可操作性,检测误差保持在[-0.38,0.21]区间内。     

Aggregated oviposition inDelia antiqua (Meigen): A case for mediation by semiochemicals

Experiments conducted in the laboratory tested the hypotheses that aggregated oviposition by onion maggot flies,Delia antiqua (Meigen), is caused by stimuli associated with ovipositing females, newly laid eggs, or both. Using a paired oviposition station bioassay that eliminated visual stimuli associated with the treatment under study, 67% of the eggs laid by caged females were in response to the odor of females already ovipositing on an onion slice, as opposed to 33% of the eggs laid in response to an onion slice alone. When newly laid eggs were transferred to onion slices and held for either 24 or 48 hr before being bioassayed against similarly aged untreated onions, 74% and 97% of the eggs were laid at the egg-treated onion stations, respectively. Similar results were achieved when an aqueous wash of newly laid eggs was applied to the onion slice. When the egg wash was processed through a bacterial filter or when eggs were present but not in contact with onions, all response was eliminated. These results implicate microorganisms transmitted on the egg surface in creating an attraction for ovipositing females. Heptane extracts of ovipositor tips from mated, ovipositing females induced 72% of the test females to oviposit near points at which extracts were applied to the oviposition station floor. A behavioral sequence for an optimal host-selection strategy is hypothesized, whereby host-seeking female onion flies respond to host-derived alkyl sulfides at long range and metabolic by-products of microbially infested hosts and visual cues at short range (ca. l m), with final selection of oviposition sites potentially reinforced by contact with an aggregation pheromone released or left on the substrate by ovipositing females.     

Primer and Short-Range Releaser Pheromone Properties of Premolt Female Urine from the Shore Crab <Emphasis Type="Italic">Carcinus maenas</Emphasis>

The European shore crab Carcinus maenas is considered to rely on a female pheromone when mating. Evidence, however, is scarce on how the urine pheromone in itself affects males. We investigated male primer and releaser responses to female pheromones with methods that minimized effects from females, delivering female urine either as a pump-generated plume or deposited on a polyurethane sponge. We delivered the pheromone at different concentrations in far, near, and close/contact range to get a picture of how distance affects behavioral response. Our results show that substances in premolt female urine (PMU) function as primer and potent short-range releaser pheromones. Based on the olfactometer and sponge tests, we conclude that PMU stimulus in itself is sufficient to elicit increased search and mating-specific behaviors such as posing, posing search, cradle carrying, and stroking. Pheromone concentrations do not seem to be important for attenuating search and posing as long as the level is above a certain threshold concentration. Instead, pheromone levels seem to play a role in male acceptance of females, recruiting more males to respond, and generating better responses with increasing concentration.     

Distance of response to host tree models by female apple maggot flies,Rhagoletis pomonella (Walsh) (Diptera: Tephritidae): Interaction of visual and olfactory stimuli

Mature female apple maggot flies,Rhagoletis pomonella (Walsh), were released individually onto a single potted, fruitless hawthorne tree in the center of an open field. The tree was surrounded by four 1-m² plywood host tree models painted green or white, with or without synthetic host fruit odor (butyl hexanoate), and placed at one of several distances from the release tree. Each fly was permitted to forage freely on the release tree for up to 1 hr, or until it left the tree. Flies left the tree significantly sooner when green models with host fruit were present at 0.5, 1.5, or 2.5 m distance from the release tree than when these models were placed at a greater distance (4.5 m) from the release tree or when no models were present. Flies responded detectably to 1-m² models without odor up to a maximum distance of 1.5 m. These results suggest that female apple maggot flies did not detect green 1-m² models with odor 4.5 m away or models without odor 2.5 m or more away. Flies responded to white models with and without odor to a much lesser extent, both in terms of response distance and flight to and alightment upon models. Increasing model size to 2 m² increased the distance to 2.5 m at which flies responded to green models without odor. Decreasing model size to 0.5 m² reduced fly responsiveness to green or white models. The presence of host fruit odor alone, without the visual stimulus of a green model, did not influence residence time on the release tree.     

Nutrition and chemosensory perception in the elderly

The elderly person's perception of foods and food flavor is affected by age‐associated changes in the chemical senses (taste, smell, and trigeminal sensation). Both classic and modern psychophysical techniques have been applied to achieve some understanding of these changes.

Taste threshold sensitivity declines with age; however, the magnitude of the decline and the degree to which taste qualities are differentially affected remains to be understood. Suprathreshold taste intensity perception is affected by age, but there is a differential effect of taste quality.

Experiments with blended foods have indicated that both olfactory and taste deficits contribute to older people's difficulty with food identification. Experiments assessing threshold sensitivity, suprathreshold intensity, and suprathreshold identification have all demonstrated significant impairment in olfaction in old age. In fact, these effects are far greater than in the taste system.

Patients with Alzheimer's disease show even greater olfactory deficits than normal elderly and the effect is related to the degree of dementia. We have ruled out nasal disease in these patients as the primary causes of olfactory insensitivity, because significant impairment remains when the influence of nasal airflow and nasal cytology has been removed statistically. Both normal elderly and patients with Alzheimer's disease show impairment in odor memory. Sensitivity to, familiarity with, and identifiability of the odors all play a role in odor memory performance.

Flavor preference also changes over the lifespan. Older subjects, for instance, rate high concentration of sugar and salt as pleasanter than young subjects do. Multiple influences contribute to this phenomenon. Elderly persons and those of lower nutritional status have shown preferences for higher concentrations of casein hydrolysate than young persons and those of higher nutritional status, suggesting that dietary preference can be related to chemosensory cues.

There are significant age‐associated changes in chemosensory perception that have the potential to interact with dietary selection and nutrition in the elderly. A better understanding of these phenomena may promote health and well‐being in the elderly.     

Species-Specific Antennal Responses to Tibial Fragrances by Male Orchid Bees

Male neotropical orchid bees (Euglossini) collect odoriferous substances from orchids and other sources and store them in tibial pouches, accumulating complex and species-specific bouquets. These fragrances are later exposed at display sites, presumably to attract females or conspecific males or both. We hypothesized that the necessity to detect and recognize specific fragrance bouquets has led to peripheral chemosensory specializations in different species of orchid bees. To test this, excised male antennae of four species of Euglossa were stimulated with complete tibial extracts of the same four species in a crosswise experiment. In the majority of the tested extracts, the amplitude of the electroantennogram (EAG) response was significantly different between species and always maximal in males of the extracted species. This effect did not appear to result from a given species' increased sensitivity toward certain attractive components: gas chromatography with electroantennographic detection (GC-EAD) of one extract of Euglossa tridentata evoked similar and generalized response patterns in all four species, encompassing a total of 34 peaks that elicited antennal responses. Therefore, the species effect in EAG responses to complete extracts likely resulted from species-specific interactions of compounds at the receptor level. Antennal specialization to conspecific bouquets adds additional strength to the argument that specificity is an important evolutionary aspect of euglossine tibial fragrances. Electronic supplementary material Supplementary material to this paper is available in electronic form at     

机器嗅觉系统气味识别算法

简单介绍机器嗅觉的发展概况,依据人鼻内嗅觉感受器细胞的嗅感原理提出气敏传感器阵列的信号模型;概括分析机器嗅觉的多变量模式分析技术,从其气味识别算法的角度,重点介绍统计模式分析(线性和非线性)和智能模式分析(人工神经网络和其它)的基本方法,对机器嗅觉系统的实现具有一定的指导意义.     

基于嗅觉可视化技术的猪肉新鲜度检测

嗅觉可视化技术是使非可见物质成像（主要是气体成像）的一种无损检测新技术,属人工嗅觉模拟技术的一个新分支.使用卟啉和pH指示剂作为嗅觉可视化传感器阵列的气敏材料,检测猪肉中的优势致腐菌和新鲜度.将3种优势致腐菌-梭状芽孢杆菌、热死环丝菌、假单胞菌-分别接种至3组猪肉样本中,在3种温度--16℃,.4℃和20℃-条件下分别贮藏不同的时间后,采用扫描仪获取可视化传感器阵列与每个样本反应前后的图像信息;将阵列反应前后的颜色差值作为样本特征值,对不同的猪肉样本经不同贮藏时间后产生的挥发性气味,可视化传感器阵列显示其特定的颜色图像与其对应.结果表明,嗅觉可视化技术可以用于检测猪肉的优势致腐菌以及判断猪肉的新鲜度.