Ebrahimifard Reza, Erfle Peer, Dietzel Andreas, Garnweitner Georg
Institute for Particle Technology, Technische Universität Braunschweig, 38104 Braunschweig, Germany.
Laboratory for Emerging Nanometrology, Technische Universität Braunschweig, 38106 Braunschweig, Germany.
ACS Omega. 2022 May 19;7(21):17519-17527. doi: 10.1021/acsomega.1c06343. eCollection 2022 May 31.
In this research, we designed and fabricated an optofluidic chip for the detection and differentiation of single particles via the combination of backscattered (BSC) and forward-scattered (FSC) or side-scattered (SSC) light intensity. The high sensitivity of BSC light to the refractive index of the particles enabled an effective approach for the differentiation of individual particles based on the type of material. By recording BSC as well as FSC and SSC light intensities from single particles, transiting through the illumination zone in a microfluidic channel, the size and type of material could be detected simultaneously. The analysis of model samples of polystyrene (PS), as a primary microplastic particle, and silica microspheres showed substantially higher BSC signal values of PS because of a larger refractive index compared to the silica. The scatter plots correlating contributions of BSC (FSC-BSC and SSC-BSC) allowed a clear differentiation of PS and silica particles. To demonstrate the great potential of this methodology, two "real-life" samples containing different types of particles were tested as application examples. Commercial toothpaste and peeling gel products, as primary sources of microplastics into effluents, were analyzed via the optofluidic chip and compared to results from scanning electron microscopy. The scattering analysis of the complex samples enabled the detection and simultaneous differentiation of particles such as microplastics according to their differences in the refractive index via distinctive areas of high and low BSC signal values. Hence, the contribution of BSC light measurements in multiangle scattering of single particles realized in an optofluidic chip opens the way for the discrimination of single particles in a liquid medium in manifold fields of application ranging from environmental monitoring to cosmetics.
在本研究中，我们设计并制造了一种光流体芯片，用于通过背散射（BSC）光与前向散射（FSC）光或侧向散射（SSC）光强度的组合来检测和区分单个颗粒。BSC光对颗粒折射率的高灵敏度为基于材料类型区分单个颗粒提供了一种有效方法。通过记录单个颗粒在微流体通道中穿过照明区域时的BSC以及FSC和SSC光强度，可以同时检测颗粒的尺寸和材料类型。作为主要微塑料颗粒的聚苯乙烯（PS）模型样品和二氧化硅微球的分析表明，由于PS的折射率比二氧化硅大，其BSC信号值明显更高。将BSC的贡献（FSC-BSC和SSC-BSC）关联起来的散点图能够清晰地区分PS颗粒和二氧化硅颗粒。为了证明该方法的巨大潜力，测试了两个含有不同类型颗粒的“实际”样品作为应用实例。作为微塑料进入废水的主要来源的商业牙膏和去角质凝胶产品，通过光流体芯片进行了分析，并与扫描电子显微镜的结果进行了比较。对复杂样品的散射分析能够根据微塑料等颗粒在折射率上的差异，通过BSC信号值的高低不同区域来检测和同时区分它们。因此，在光流体芯片中实现的单颗粒多角度散射中BSC光测量的贡献，为在从环境监测到化妆品等众多应用领域的液体介质中区分单颗粒开辟了道路。
