Analysis of surface acoustic wave propagation velocity in biological function-oriented odor sensor

近年、人間と同様に「匂い」を識別できる「匂いセンサ」が開発されているが、その性能は人をはじめとする生体におよばないのが現状である。著者は「匂いセンサ」を実現するために、生体機能物質を利用したSurface Acoustic Wave (SAW)デバイスにおける弾性表面波の伝播特性を研究した。本論文は、匂い結合タンパク質を設置したSAWデバイスにおける弾性表面波の伝播特性を理論及び実験により検討した結果について述べている。室蘭工業大学の岩佐研究室では両生類のイモリを対象に嗅覚関連タンパク質を研究し、イモリ嗅上皮に特異的に発現するCynops pyrrhogaster lipocalin 遺伝子を発見した。岩佐らはこの遺伝子からできた匂い結合タンパク質をCp-Lip1と呼んでいる。また、室蘭工業大学の福田研究室では匂いセンサを実現するためにSAWデバイスを研究している。本研究では、このCp-Lip1匂い結合タンパク質とSAWデバイスを匂いセンサに用いている。第2章では、弾性表面波の伝播を理論解析し、SAWデバイスにおける弾性表面波の伝播速度の理論式を導出した。室蘭工業大学の福田研究室で開発したSAWデバイスにおいて、SAWの伝播経路上に匂い結合タンパク質を含む液体層を作成した。この液体層では、レーリー波、漏洩レーリー波、縦波が伝播する。この理論解析により、このSAWデバイスの液体層で伝播するSAWの総伝播速度を明らかにした。第3章では、SAWデバイスにおいて、試料溶液を溝に置いた時のSAWの伝播特性の測定について述べた。測定実験では、IDT電極間距離は25.00mm、圧電材料は42Y-45X STカット水晶基板のSAWデバイスを使った。このSAWデバイスの周波数は157.6MHzである。まず、エタノールとBSAタンパク質を試料溶液として使って、導出したSAWの伝播速度の理論式が有効であることを明らかにした。次に、匂い分子を使った実験で使用する溝の適切なサイズを決めるために、二つの異なるサイズの溝を使ってSAWの受信側IDTの感度を調べた。その結果、溝幅0.41mm-溝高さ0.26mmの溝基板は溝幅0.24mm-溝高さ0.25mmの溝基板よりSAWの受信側IDTの感度が良いことを明らかにした。匂い分子を同定する実験では、Cp-Lip1匂い結合タンパク質に対して5種類の単一匂い分子の影響を調べた。実験では、異なる濃度の5種類の単一匂い分子をSAWデバイス上でCp-Lip1に反応させ、SAWの伝播特性の変化を測定した。第4章では、SAWデバイスにおけるこの5種類の単一匂い分子の理論速度を計算し、実験結果との比較を述べた。SAWデバイスにおける弾性表面波の実験結果と理論計算の伝播速度はほぼ一致していた。以上のように、本論文は、Cp-Lip1を用いたSAW型匂いセンサを使って匂い分子を同定できる可能性があることを示した。Biological function-oriented odor sensors are required to fulfil needs for various applications of biological electronic nose systems. Surface acoustic wave (SAW) devices, in which Rayleigh waves propagate, have also been studied for biological function-oriented odor sensors. I describe measurement of SAWs velocities to identify five odorant molecules by using a SAW device as the biological function odor sensor. Dr. Tatsuo Iwasa in Muroran Institute of Technology has studied olfactory related proteins in amphibian newts. He found a Cynops pyrrhogaster lipocalin (Cp-Lip1) protein, an odorant-binding protein discovered in newts, which can combine with various hydrophobic odorant molecules. Dr. Hisashi Fukuda in Muroran Institute of Technology has studied SAW devices to realize odor sensors. In this study, I used the Cp-Lip1 odorant-binding protein and the SAW device as an odor sensor. In chapter 2, I determined a new mathematical formula for estimating the velocity of SAWs. Surface acoustic waves propagate from InterDigital Transducer (IDT) generating leaky Rayleigh waves when liquid is on the quartz substrates in the SAW device developed in Dr. Fukuda laboratory. The Leaky Rayleigh waves travel radiating longitudinal waves into a liquid layer. On the other hand, Rayleigh waves propagate in the vacuum-solid interface. In chapter 3, I measured the propagation velocities in a SAW device in which ethanol, BSA protein and five kinds of odorant molecules were used as liquid medium. I used ethanol and BSA protein as sample solutions and clarified that the theoretical formula for estimating the velocity of SAWs is effective. In order to determine the appropriate size of the groove two different sizes of grooves were examined. The groove with width-height of 0.41mm-0.26mm showed higher intensity than the groove with width-height of 0.24mm-0.25mm did. Then five kinds of odorant molecule solutions were placed on the SAW device which had the groove with width-height is 0.41mm-0.26mm. I identified five kinds of odorant molecules in the measurement of SAWs velocities. In chapter 4, I compared between the theoretical and the experimental velocities in order to verify validity of the SAW device for the biological function-oriented odor sensor. I showed that the theoretical and the experimental propagation velocities of the five kinds of odorant molecule solutions were nearly identical. I have described that our frequency equation can predict different odorant molecules in the SAW device. My study provides the basis for a new method for developing biological function-oriented odor sensors.室蘭工業大学 (Muroran Institute of Technology)博士（工学

Piezoelectric microsensors for semiochemical communication

Chemical communication plays vital role in the mediating the behaviour of an organism living in the “odour space”. The mechanisms by which odours are generated and detected by the organism has evolved over thousands of years and thus the potential advantages of translating this system into a fully functional communication system has opened new avenues in the area of multi-disciplinary research. This formed the basis of the Biosynthetic Infochemical Communications project – iCHEM whose central aim was to develop a new class of communication technology based on the biosynthesis pathways of the moth, S. littoralis. This novel infochemical communication system would consist of a “chemoemitter” unit which would generate a precise mix of infochemicals which after travelling through the odour space would be detected by a complementary tuned detector – the “chemoreceiver” unit comprising of a ligand specific detection element and an associated biophysical model functioning similar to the antennal lobe neuron of the moth. This combined novel system will have the capability of communicating by the help of chemicals only, in the vapour or liquid phase. For the work presented in this thesis, the novel concept of infochemical communication has been examined in the vapour and liquid phase by employing piezoelectric microsensors. This has been achieved and demonstrated throughout the thesis by employing chemo-specific acoustic wave microsensors. For vapour phase assessment, quartz crystal microbalance, were coated with different organic polymer coatings and incorporated in a prototype infochemical communication system detecting encoded volatiles. For liquid phase assessment, shear horizontal surface acoustic wave (SH-SAW) microsensors were specifically designed and immobilised within Sf9 insect cells. This GPCR based whole cell biosensing system was then employed to detect ligand specific activations thus acting as a precursor to the development of a fully functionalised OR based signalling system, thus contributing to the growing field of communication and labelling technology

Airborne chemical sensing with mobile robots

Airborne chemical sensing with mobile robots has been an active research areasince the beginning of the 1990s. This article presents a review of research work in this field,including gas distribution mapping, trail guidance, and the different subtasks of gas sourcelocalisation. Due to the difficulty of modelling gas distribution in a real world environmentwith currently available simulation techniques, we focus largely on experimental work and donot consider publications that are purely based on simulations

Applications and Advances in Electronic-Nose Technologies

Electronic-nose devices have received considerable attention in the field of sensor technology during the past twenty years, largely due to the discovery of numerous applications derived from research in diverse fields of applied sciences. Recent applications of electronic nose technologies have come through advances in sensor design, material improvements, software innovations and progress in microcircuitry design and systems integration. The invention of many new e-nose sensor types and arrays, based on different detection principles and mechanisms, is closely correlated with the expansion of new applications. Electronic noses have provided a plethora of benefits to a variety of commercial industries, including the agricultural, biomedical, cosmetics, environmental, food, manufacturing, military, pharmaceutical, regulatory, and various scientific research fields. Advances have improved product attributes, uniformity, and consistency as a result of increases in quality control capabilities afforded by electronic-nose monitoring of all phases of industrial manufacturing processes. This paper is a review of the major electronic-nose technologies, developed since this specialized field was born and became prominent in the mid 1980s, and a summarization of some of the more important and useful applications that have been of greatest benefit to man

Coral reef soundscapes may not be detectable far from the reef

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 6 (2016): 31862, doi:10.1038/srep31862.Biological sounds produced on coral reefs may provide settlement cues to marine larvae. Sound fields are composed of pressure and particle motion, which is the back and forth movement of acoustic particles. Particle motion (i.e., not pressure) is the relevant acoustic stimulus for many, if not most, marine animals. However, there have been no field measurements of reef particle motion. To address this deficiency, both pressure and particle motion were recorded at a range of distances from one Hawaiian coral reef at dawn and mid-morning on three separate days. Sound pressure attenuated with distance from the reef at dawn. Similar trends were apparent for particle velocity but with considerable variability. In general, average sound levels were low and perhaps too faint to be used as an orientation cue except very close to the reef. However, individual transient sounds that exceeded the mean values, sometimes by up to an order of magnitude, might be detectable far from the reef, depending on the hearing abilities of the larva. If sound is not being used as a long-range cue, it might still be useful for habitat selection or other biological activities within a reef.This work was funded by the Woods Hole Oceanographic Institution Ocean Ventures Fund, the PADI Foundation, the Woods Hole Oceanographic Institution Access To The Sea program, and the National Science Foundation grant OCE-1536782

Sensores: De los biosensores a la nariz electrónica

The recent advances in sensor devices have allowed the developing of new applications in many technological fields. This review describes the current state-of-the-art of this sensor technology, placing special emphasis on the food applications. The design, technology and sensing mechanism of each type of sensor are analysed. A description of the main characteristics of the electronic nose and electronic tongue (taste sensors) is also given. Finally, the applications of some statistical procedures in sensor systems are described briefly.Los recientes avances en los sistemas de sensores han permitido el desarrollo de nuevas aplicaciones en muchos campos tecnológicos. Este artículo de revisión describe el estado actual de esta nueva tecnología, con especial énfasis en las aplicaciones alimentarias. El diseño, la tecnología y el mecanismo sensorial de cada tipo de sensor son analizados en el artículo. También se describen las principales características de la nariz y la lengua electrónica (sensores de sabor). Finalmente, se describe brevemente el uso de algunos procedimientos estadísticos en sistemas de sensores.Peer reviewe

Advancements in microfabricated gas sensors and microanalytical tools for the sensitive and selective detection of odors

In recent years, advancements in micromachining techniques and nanomaterials have enabled the fabrication of highly sensitive devices for the detection of odorous species. Recent efforts done in the miniaturization of gas sensors have contributed to obtain increasingly compact and portable devices. Besides, the implementation of new nanomaterials in the active layer of these devices is helping to optimize their performance and increase their sensitivity close to humans’ olfactory system. Nonetheless, a common concern of general-purpose gas sensors is their lack of selectivity towards multiple analytes. In recent years, advancements in microfabrication techniques and microfluidics have contributed to create new microanalytical tools, which represent a very good alternative to conventional analytical devices and sensor-array systems for the selective detection of odors. Hence, this paper presents a general overview of the recent advancements in microfabricated gas sensors and microanalytical devices for the sensitive and selective detection of volatile organic compounds (VOCs). The working principle of these devices, design requirements, implementation techniques, and the key parameters to optimize their performance are evaluated in this paper. The authors of this work intend to show the potential of combining both solutions in the creation of highly compact, low-cost, and easy-to-deploy platforms for odor monitoringPostprint (published version

Sensores: De los biosensores a la nariz electrónica

The recent advances in sensor devices have allowed the developing of new applications in many technological fields. This review describes the current state-of-the-art of this sensor technology, placing special emphasis on the food applications. The design, technology and sensing mechanism of each type of sensor are analysed. A description of the main characteristics of the electronic nose and electronic tongue (taste sensors) is also given. Finally, the applications of some statistical procedures in sensor systems are described briefly.Los recientes avances en los sistemas de sensores han permitido el desarrollo de nuevas aplicaciones en muchos campos tecnológicos. Este artículo de revisión describe el estado actual de esta nueva tecnología, con especial énfasis en las aplicaciones alimentarias. El diseño, la tecnología y el mecanismo sensorial de cada tipo de sensor son analizados en el artículo. También se describen las principales características de la nariz y la lengua electrónica (sensores de sabor). Finalmente, se describe brevemente el uso de algunos procedimientos estadísticos en sistemas de sensores

How spatial constraints on efficacy and dynamic signaling alignment shape animal communication

Effective communication is important to the survival and reproduction of many organisms. Signal transmission and reception have spatial constraints that interact to determine effectiveness. Signals are often best perceived from specific angles, and sensory systems may be limited in their ability to detect or interpret incoming stimuli from certain directions. Alignment between these directional biases can be critical to effective communication. Misalignment of either signal or sensor may disrupt signal perception. Signals also degrade during the distance traveled from signaler to receiver. Thus, how animals position themselves during communication may be under selection. Despite this, we know little about the spatial arrangement of signalers and receivers, what behaviors influence positioning, or the causes and consequences of variation in positioning. To address this fundamental gap in knowledge, I developed a geometric framework for studying the spatial constraints of communication and how they shape positioning across visual, sound, and chemical signaling. To investigate respective roles of signaler and receiver in managing these spatial constraints, I then characterized the spatial dynamics of visual signaling in the jumping spider Habronattus pyrrithrix. Males perform an elaborate courtship dance which includes arm waves and colorful ornaments; the latter are not visible from the side. The female can only perceive colors of male displays when they are presented in her frontal field of view. I recorded relative positions and orientations of both actors throughout courtship and established the role of each sex in maintaining signaling alignment. Finally, I tested how males control female orientation, and respond to signaling challenges. Using video playback, I asked how males’ arm-waving display and the visual environment determine how effectively they attracted female attention, as well as how males respond to variation in their signaling environment. These studies reveal that signaling alignment is frequently disrupted by females turning away from males, but that male arm-waving effectively re-captures her attention. Males also modulate displays in response to changing spatial and environmental conditions. Overall, this dissertation reveals the widespread role of spatial constraints in driving signaling behavior, and demonstrates that the spatial arrangement of signaler and receiver must be managed dynamically through behavioral responses