Nano- and microparticles are expected to have several functionalities, and the ability to control size and shape is an advantage of using nano-/microparticles. This study investigated a possibility that the sizes of nano-/microparticle can be used to extract new information on structures in a fractured medium. Flow experiments were conducted to observe the particle transport in a micromodel on which a single fracture and rock matrix (grain and pore space) was fabricated on a silicon wafer. Water and nano-/microparticles were injected into the micromodel, and the droplets were collected at the outlet. Tunable Resistive Pulse Sensing (TRPS) was used to measure the frequency distributions of particle diameters from each droplet at each time. The result shows that the larger particles were observed only at early time, while the smaller particles were detected at early time and also at late time. This indicates that the larger particles flow in a fracture quickly, while smaller particles migrate through both fracture and matrix over a wider range of time. Particles with different sizes transport through fractured media differently depending on the fracture structures. The tracer response of nano- and microparticles may be useful to evaluate the fracture structures and the flow properties for different flow pathways.

中文翻译：

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纳米/微粒传输表征裂隙多孔介质结构的实验研究

纳米和微粒预计具有多种功能，控制尺寸和形状的能力是使用纳米/微粒的优势。这项研究调查了一种可能性，即纳米/微粒的大小可用于提取有关断裂介质中结构的新信息。进行了流动实验以观察微观模型中的粒子传输，在该模型上，在硅晶片上制造了单个裂缝和岩石基质（颗粒和孔隙空间）。将水和纳米/微粒注入微模型，并在出口处收集液滴。可调谐电阻脉冲传感 (TRPS) 用于测量每次来自每个液滴的粒径的频率分布。结果表明，仅在早期观察到较大的颗粒，而较小的颗粒在早期和晚期都被检测到。这表明较大的颗粒在裂缝中快速流动，而较小的颗粒在更宽的时间内通过裂缝和基质迁移。具有不同尺寸的颗粒根据裂缝结构不同地通过裂缝介质传输。纳米和微粒的示踪剂响应可用于评估不同流动路径的裂缝结构和流动特性。