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Understanding tympanal mechanics in insect ears

了解昆虫耳朵的鼓膜力学

基本信息

批准号：
BB/I009671/1
负责人：
Daniel Robert
金额：
$ 60.07万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FI009671%2F1
关键词：
Understanding tympanal mechanics insect ears

项目摘要

Insects have marvelous ears. Some insects, like mosquitoes, use antennae in front of their heads to detect sounds, mainly those of approaching females. Notably, our research has shown the ear of a mosquito is as sensitive to vibrations as the human ear and contains just as many vibration sensitive cells -16,000. Other insect, like crickets, locust and some rare flies use ears equipped with an eardrum, or tympanal membrane. The human ear also has an eardrum that serves to convert sound into motion. This motion is in turn transduced into the electrical signal that vibration sensitive cells then convey to the brain. Because sound-induced vibrations are very small, this process is extremely delicate. In insects, a similar process takes place, but with an ear that is sometimes 100 times smaller. Our research and that of others has shown that the eardrums of insects are sophisticated instruments that evolved for hundreds of millions of years to extract the faint sound energy and deliver it to the vibration sensitive cells. In particular we showed that in locusts the tympanum has at least one additional function: sorting the tone frequencies relevant to the life and survival of the animal. This is a form of mechanical information processing that takes place even before neuronal processing. Normal membrane vibrations are in the range of nanometers and take the shape of a traveling wave across the membrane surface area. We discovered that this wave is exquisitely timed, lasting 100 millionth of a second, strongly resembling a tsunami coming up to a shore. Interestingly, the propagation of this biological nanotsunami depends on the frequency of the sound that creates it, not its direction. The build up of the wave in effect provides the animal with the perception of tones. The work proposed aims at discovering the exact material properties and membrane architecture that allow for that wave to build up and generate directional frequency decomposition. We will use laser beams to monitor the vibrations, using the Doppler effect applied to light, to detect membrane motion with a resolution of the diameter of an atom of hydrogen. For the first time we will use focused ion beam milling to modify the geometry, tension and mass characteristics of the membranes and then explore the resulting vibrational behaviour. Ion beam milling uses an atomically thin jet of metal ions projected onto the object and can be used to either cut through objects, hard or soft, or add matter to that object. This technique has never been used to study micro and nanomechanics. Importantly, mathematical modeling will guide the search for mechanisms, by predicting the best way to alter the membrane to generate desired effects and thereby also delineating the key physical parameters, materials and architecture, that are sufficient and necessary for membrane function. Because we use three species of tympanate insects, we will be able to compare and contrast the results and adequacy of the approach. Why the membrane of the locust is vibrating one way, and that of the cricket another way, with different information coding properties, is still elusive. Using focused ion beams we will attempt to add or remove functions from the respective species, and understand what evolution by natural selection has achieved in the developing the tiny ears of insects. From the proposed research, we will also learn how to make better microphones, using in technology what we have observed in biology. This is especially useful when the goal is manufacture robust microphones a millimeter in size and less. Examples of application pertain to hearing aid microphones capable of on-board frequency and directional processing as well as subminiature microphone for electronic application with minimal power consumption.

昆虫有很棒的耳朵。有些昆虫，如蚊子，用它们头前的触角来探测声音，主要是接近雌性的声音。值得注意的是，我们的研究表明，蚊子的耳朵对振动的敏感度与人的耳朵一样，并且包含同样多的振动敏感细胞-16，000。其他昆虫，如蟋蟀，蝗虫和一些罕见的苍蝇使用耳朵配备了鼓膜，或鼓膜。人耳也有一个鼓膜，用于将声音转换为运动。这种运动又被转换成电信号，然后振动敏感细胞将其传递到大脑。由于声音引起的振动非常小，这个过程非常微妙。在昆虫中，也发生类似的过程，但耳朵有时要小100倍。我们和其他人的研究表明，昆虫的鼓膜是经过数亿年进化的复杂仪器，可以提取微弱的声能并将其传递给振动敏感细胞。特别是，我们发现，在蝗虫的鼓膜至少有一个额外的功能：排序的音调频率相关的生活和生存的动物。这是一种机械信息处理的形式，甚至发生在神经元处理之前。正常的膜振动在纳米范围内，并采取跨膜表面区域的行波的形状。我们发现这波的时间非常精确，持续了一亿分之一秒，非常类似于海啸冲上海岸。有趣的是，这种生物纳米海啸的传播取决于产生它的声音的频率，而不是方向。波的建立实际上为动物提供了音调的感知。这项工作的目的是发现确切的材料特性和膜结构，使波建立和产生定向频率分解。我们将使用激光束来监测振动，利用应用于光的多普勒效应，以氢原子直径的分辨率来检测膜运动。我们将首次使用聚焦离子束铣削来修改膜的几何形状、张力和质量特性，然后探索由此产生的振动行为。离子束铣削使用原子级薄的金属离子喷射投射到物体上，并且可以用于切割硬或软的物体，或者向该物体添加物质。这项技术从未被用于研究微观和纳米力学。重要的是，数学建模将通过预测改变膜以产生所需效果的最佳方式来指导对机制的研究，从而也描绘了对膜功能来说足够和必要的关键物理参数、材料和结构。因为我们使用三种鼓膜昆虫，我们将能够比较和对比的结果和适当的方法。为什么蝗虫的膜以一种方式振动，而蟋蟀的膜以另一种方式振动，具有不同的信息编码特性，仍然是难以捉摸的。使用聚焦离子束，我们将尝试添加或删除相应物种的功能，并了解自然选择在昆虫小耳朵的发展中取得了什么样的进化。从拟议的研究中，我们还将学习如何制造更好的麦克风，在技术上使用我们在生物学中观察到的东西。当目标是制造尺寸小于或等于1毫米的坚固麦克风时，这一点尤其有用。应用实例涉及能够进行板上频率和定向处理的助听器麦克风以及用于电子应用的超小型麦克风，功耗最小。