Ambient suspended particulate matter(PM)(primarily with particle diameter 2.5m or less,i.e.,PM2.5)can adversely affect ecosystems and human health.Currently,optical particle sensors based on light scattering dominate ...Ambient suspended particulate matter(PM)(primarily with particle diameter 2.5m or less,i.e.,PM2.5)can adversely affect ecosystems and human health.Currently,optical particle sensors based on light scattering dominate the portable PM sensing market.However,the light scattering method has poor adaptability to different-sized PM and adverse environmental conditions.Here,we design and develop a portable PM sensing microsystem that consists of a micromachined virtual impactor(VI)for particle separation,a thermophoretic deposition chip for particle collection,and an extended-gate field-effect transistor(FET)for particle analysis.This system can realize on-site separation,collection,and analysis of aerosol particles without being influenced by environmental factors.In this study,the design of the VI is thoroughly analyzed by numerical simulation,and mixtures of different-sized silicon dioxide(SiO2)particles are used in an experimental verification of the performance of the VI and FET.Considering the low cost and compact design of the whole system,the proposed PM analysis microsystem has potential for PM detection under a wide range of conditions,such as heavily polluted industrial environments and for point-of-need outdoor and indoor air quality monitoring.展开更多
Monodisperse particles are useful across a wide range of industrial applications,such as LCD displays,solar cells and rechargeable batteries,due to their uniformly small sizes.However,generating high volumes of monodi...Monodisperse particles are useful across a wide range of industrial applications,such as LCD displays,solar cells and rechargeable batteries,due to their uniformly small sizes.However,generating high volumes of monodisperse particles remains challenging.In this study,it was aimed to generate mono-disperse aerosols by classifying micrometer-scale solid aerosol particles within a narrow size range.Accordingly,a new particle-size classification device with two virtual impactors connected in series and clean air cores was developed.The first-stage virtual impactor had a slightly larger cutoff size than the second-stage,and the major flow discharged from the first-stage was directed to the second-stage.The target particle size range was altered by changing the nozzle sizes in the first and second stages or by adjusting the flow rate.Subsequently,the classification performance of the two-stage virtual impactor was simulated and validated through an experiment using Arizona test dust.The implemented combi-nations of cutoff sizes for the first and second stages were 3.0 and 2.0μm,3.9 and 2.7μm,or 6.7 and 4.8μm.As a result,monodisperse aerosol particles were classified at a geometric standard deviation of 1.04-1.14 and a particle size range of 2-6.7μm.The two-stage virtual impactor developed herein may be useful for various research and performance evaluations,as it can classify micrometer-scale solid particle aerosols that exhibit high monodispersity.展开更多
为满足环境气溶胶在线进样的要求,改善电感耦合等离子体质谱计(Inductively Coupled Plasma Mass Spectrometry,ICP蛳MS)对粒子中待测核素的探测限,研制出一套具有低流量、低压降特点的狭缝虚拟撞击器,可作为气溶胶在线富集进样系统的...为满足环境气溶胶在线进样的要求,改善电感耦合等离子体质谱计(Inductively Coupled Plasma Mass Spectrometry,ICP蛳MS)对粒子中待测核素的探测限,研制出一套具有低流量、低压降特点的狭缝虚拟撞击器,可作为气溶胶在线富集进样系统的关键部件与ICPˉMS联用。本文介绍了该狭缝虚拟撞击器的研制情况:首先由ICP蛳MS的进样条件,根据经验公式完成了理论设计,确定进样流量为11L/min,强流与弱流的流量比为10,喷射狭缝宽度为1mm,长宽比为10;然后用计算流体动力学软件Fluent R对上述结构内部的流场和粒子运动径迹进行了数值模拟,考察了喷射狭缝与收集狭缝的间距G、收集狭缝的宽度Wc及其进口曲率半径的加工偏差对收集效率的影响,得到了较优化的取值范围:G取1.0～1.2mm,Wc取1.4～1.6mm,此时的切割粒径D50约2.5μm;加工出狭缝虚拟撞击器的原型装置,对其分别用室内空气气溶胶和荧光素钠标记的单分散油酸粒子进行富集性能测量。实测结果表明:空气动力学等效直径在2.5～5μm范围内的粒子浓度得到了明显富集,5μm的粒子的富集因子达到极大值7。展开更多
基金supported by the National Natural Science Foundation of China(Nos.91743110,61674114,and 21861132001)the National Key R&D Program of China(Nos.2017YFF0204604 and 2018YFE0118700)+1 种基金Tianjin Applied Basic Research and Advanced Technology(No.17JCJQJC43600),the“111”Project(No.B07014)the Foundation for Talent Scientists of Nanchang Institute for Micro-technology of Tianjin University.
文摘Ambient suspended particulate matter(PM)(primarily with particle diameter 2.5m or less,i.e.,PM2.5)can adversely affect ecosystems and human health.Currently,optical particle sensors based on light scattering dominate the portable PM sensing market.However,the light scattering method has poor adaptability to different-sized PM and adverse environmental conditions.Here,we design and develop a portable PM sensing microsystem that consists of a micromachined virtual impactor(VI)for particle separation,a thermophoretic deposition chip for particle collection,and an extended-gate field-effect transistor(FET)for particle analysis.This system can realize on-site separation,collection,and analysis of aerosol particles without being influenced by environmental factors.In this study,the design of the VI is thoroughly analyzed by numerical simulation,and mixtures of different-sized silicon dioxide(SiO2)particles are used in an experimental verification of the performance of the VI and FET.Considering the low cost and compact design of the whole system,the proposed PM analysis microsystem has potential for PM detection under a wide range of conditions,such as heavily polluted industrial environments and for point-of-need outdoor and indoor air quality monitoring.
基金supported by the National Research Foundation of Korea (NRF)grant funded by the Korea government (MSIT) (grant No.RS-2024-00346834).
文摘Monodisperse particles are useful across a wide range of industrial applications,such as LCD displays,solar cells and rechargeable batteries,due to their uniformly small sizes.However,generating high volumes of monodisperse particles remains challenging.In this study,it was aimed to generate mono-disperse aerosols by classifying micrometer-scale solid aerosol particles within a narrow size range.Accordingly,a new particle-size classification device with two virtual impactors connected in series and clean air cores was developed.The first-stage virtual impactor had a slightly larger cutoff size than the second-stage,and the major flow discharged from the first-stage was directed to the second-stage.The target particle size range was altered by changing the nozzle sizes in the first and second stages or by adjusting the flow rate.Subsequently,the classification performance of the two-stage virtual impactor was simulated and validated through an experiment using Arizona test dust.The implemented combi-nations of cutoff sizes for the first and second stages were 3.0 and 2.0μm,3.9 and 2.7μm,or 6.7 and 4.8μm.As a result,monodisperse aerosol particles were classified at a geometric standard deviation of 1.04-1.14 and a particle size range of 2-6.7μm.The two-stage virtual impactor developed herein may be useful for various research and performance evaluations,as it can classify micrometer-scale solid particle aerosols that exhibit high monodispersity.
