权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Methods for improved size resolution for particle impactors

提高粒子撞击器尺寸分辨率的方法

基本信息

批准号：
1804304
负责人：
John Saylor
金额：
$ 30.35万
依托单位：
Clemson University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804304&HistoricalAwards=false
关键词：
Methods improved size resolution particle

项目摘要

The presence of particles in the atmosphere has a significant impact on human health. Continued exposure to pollutant particles contributes to ailments such as asthma, lung cancer, and chronic obstructive pulmonary disorder (COPD). In addition, studies have shown that emergency room visits and mortality rates are correlated to the level of particulate pollution in the air on that day. The size of a particle has a significant effect on where it deposits in the lung and therefore on its health impact. For example, micron scale particles are very effective at depositing in the deepest recesses of the lung, while larger particles tend to deposit in the upper bronchial tubes and in the pharynx. Recently, animal studies have shown that nanometer sized particles can translocate from the lungs to other organs, including the brain. Many studies have been conducted which measure the number and size distribution of particles in the atmosphere and in industrial work environments, with the goal of understanding the formation and removal of particles from the air. Particle counters, instruments which size and count particles for diameters ranging from a few nanometers to hundreds of microns, are an indispensable tool in these studies. Particle counters exist which have good size resolution over this range of particle diameters. However, this type of counter is expensive, fragile, and barely portable, as they use lasers, vacuum chambers, and high voltage. A cheaper, more robust, and highly portable alternative is a device called a cascade impactor. Unfortunately, these devices have poor particle diameter resolution, a significant problem given the effect of particle diameter on human health. This research takes advantage of newly discovered physics of particles in impactors to dramatically extend their sizing capabilities. Successful completion of this research will enable studies that would not otherwise be possible. This research therefore serves as a force multiplier, enabling particle scientists and epidemiologists to dramatically extend their capabilities. Additionally, this work will result in the training of at least one graduate student and several undergraduates in the field of particle science, an important discipline that is typically not part of graduate or undergraduate engineering curricula.Impactor cascades are used to size and count particles in air for a large range of applications, including epidemiological studies, monitoring of worker exposure in industries such as mining and construction, and studies of atmospheric pollution. While these devices can sense particles down to diameters as small as 10 nm, their diameter resolution is poor. Commercially available impactor cascades yield particle size distributions (PSDs) having at most 13 bins. This research consists of a set of computational simulations and experiments that will demonstrate how particles can be size-segregated within a single impactor stage, thereby dramatically increasing the diameter resolution of the PSDs that can be obtained from impactor cascades. Preliminary research by the principal investigator has shown that relatively minor modifications of the impactor geometry can cause particles captured by an impactor plate to be distributed in the radial direction of the plate according to their diameter. That is, larger diameter particles are located near the center of the plate and smaller ones near the periphery. This size segregation of particles allows for a virtually unlimited number of bins in PSDs obtained from impactor cascades. These preliminary results were obtained for micron scale particles. The research will explore further variations of the impactor geometry which can maximize this effect and then demonstrate its efficacy down to diameters as small as 10 nm. The principal investigator will recruit female and underrepresented minority graduate students to participate in this research, and outreach to high school students will be part of the project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

大气中颗粒物的存在对人类健康有重大影响。持续接触污染物颗粒会导致哮喘、肺癌和慢性阻塞性肺疾病 (COPD) 等疾病。此外，研究表明，急诊室就诊和死亡率与当天空气中的颗粒物污染水平相关。颗粒的大小对其在肺部的沉积位置以及对健康的影响具有重大影响。例如，微米级颗粒非常有效地沉积在肺部最深处，而较大的颗粒则倾向于沉积在上支气管和咽部。最近，动物研究表明，纳米尺寸的颗粒可以从肺部转移到其他器官，包括大脑。已经进行了许多研究来测量大气和工业工作环境中颗粒的数量和尺寸分布，目的是了解空气中颗粒的形成和去除。粒子计数器是对直径从几纳米到数百微米的粒子进行大小和计数的仪器，是这些研究中不可或缺的工具。现有的粒子计数器在该粒子直径范围内具有良好的尺寸分辨率。然而，这种类型的计数器昂贵、易碎且不易携带，因为它们使用激光、真空室和高电压。一种更便宜、更坚固且高度便携的替代方案是一种称为级联冲击器的设备。不幸的是，这些设备的粒径分辨率较差，考虑到粒径对人类健康的影响，这是一个重大问题。这项研究利用了冲击器中新发现的粒子物理学，极大地扩展了它们的尺寸测量能力。这项研究的成功完成将使原本不可能进行的研究成为可能。因此，这项研究起到了力量倍增器的作用，使粒子科学家和流行病学家能够极大地扩展他们的能力。此外，这项工作还将对粒子科学领域的至少一名研究生和几名本科生进行培训，粒子科学是一门通常不属于研究生或本科生工程课程一部分的重要学科。冲击级联用于对空气中的颗粒进行大小和计数，其应用范围广泛，包括流行病学研究、监测采矿和建筑等行业工人的暴露情况以及大气污染研究。虽然这些设备可以感应直径小至 10 nm 的颗粒，但它们的直径分辨率很差。市售的级联冲击器可产生最多 13 个仓的粒度分布 (PSD)。这项研究由一组计算模拟和实验组成，将演示如何在单个冲击器级内对颗粒进行尺寸分离，从而显着提高从冲击器级联获得的 PSD 的直径分辨率。首席研究员的初步研究表明，撞击器几何形状的相对较小的修改可以导致撞击板捕获的颗粒根据其直径分布在板的径向方向上。也就是说，较大直径的颗粒位于板的中心附近，而较小直径的颗粒位于板的周边附近。这种颗粒尺寸分离使得从冲击器级联获得的 PSD 中的箱体数量几乎不受限制。这些初步结果是针对微米级颗粒获得的。该研究将探索冲击器几何形状的进一步变化，以最大限度地发挥这种效果，然后证明其功效小至 10 nm 的直径。首席研究员将招募女性和代表性不足的少数族裔研究生参与这项研究，高中生的推广也将成为该项目的一部分。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。