Juneja Subhavna, Zhang Boxin, Wang Alan X
School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331, United States.
Department of Electrical and Computer Engineering, Baylor University, Waco, Texas 76798, United States.
ACS Omega. 2023 May 1;8(19):17151-17158. doi: 10.1021/acsomega.3c01519. eCollection 2023 May 16.
Optofluidic sensors have accelerated the growth of smart sensor platforms with improved sensitivity, reliability, and innovation. In this article, we report the integration of a surface-enhanced Raman scattering (SERS) material consisting of silver nanoparticle-decorated diatomaceous earth (AgNPs-DE) with a flow-through microfluidic device, building up a hierarchical structured micro-total analysis system (μ-TAS) capable of achieving part-per-quadrillion (ppq)-level sensitivity. By the synergic integration of millimeter-scale microfluidic devices and porous laboratory filter paper with a micrometer-sized crosslinked cellulosic network that carries SERS-active AgNPs-DE, which possesses submicron to nanometer regimes of photonic crystals and plasmonic nanostructures, we achieved enhanced mass-transfer efficiency and unprecedented detection sensitivity. In our experiment, fentanyl as the testing analyte at different concentrations was measured using a portable Raman spectrometer. The limit of detection (LOD) was estimated to be 10 ppq from a small detection volume of 10 mL with an ultrafast time of sensing (TOS) of 3 min. To attain comparable signals, the traditional soaking method took more than 90 min to detect 10 part-per-trillion fentanyl from a 10 mL sample. Compared with existing SERS sensing results of fentanyl, the limit-defying μ-TAS reduced the LOD-TOS product by almost 4 orders of magnitude, which represents a new stage of ultrafast sensing of extremely low concentration analytes.
光流控传感器通过提高灵敏度、可靠性和创新性，加速了智能传感器平台的发展。在本文中，我们报告了一种由银纳米颗粒修饰的硅藻土（AgNPs-DE）组成的表面增强拉曼散射（SERS）材料与流通式微流控装置的集成，构建了一个能够实现千万亿分之一（ppq）级灵敏度的分层结构微全分析系统（μ-TAS）。通过将毫米级微流控装置和多孔实验室滤纸与带有SERS活性AgNPs-DE的微米级交联纤维素网络进行协同集成，该网络具有亚微米到纳米尺度的光子晶体和等离子体纳米结构，我们实现了增强的传质效率和前所未有的检测灵敏度。在我们的实验中，使用便携式拉曼光谱仪测量了不同浓度的芬太尼作为测试分析物。从10 mL的小检测体积和3分钟的超快传感时间（TOS）估计检测限（LOD）为10 ppq。为了获得可比的信号，传统的浸泡方法从10 mL样品中检测10万亿分之一的芬太尼需要90多分钟。与现有的芬太尼SERS传感结果相比，这种突破极限的μ-TAS将LOD-TOS乘积降低了近4个数量级，这代表了极低浓度分析物超快传感的新阶段。
