Kim Junho, Jeon Hwisu, Lee Kyunghun, Kim Taesung
Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-Gil, Ulsan 44919, Republic of Korea.
Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-Gil, Ulsan 44919, Republic of Korea.
Lab Chip. 2025 Jun 30. doi: 10.1039/d5lc00420a.
The separation of micro-/nanoparticles on a chip is an important research area with significant applications in biology, biomedical engineering, and materials science. However, conventional single-field separation strategies exhibit certain limitations, such as dependence on particle properties, size selectivity, and a restricted range of separable targets. These limitations can be overcome by combining complementary physical fields, which allows the strengths of each individual field to compensate for the weaknesses of others. In this study, we present a multi-physical field (MPF)-based approach that synergistically combines inertial and thermophoretic effects to achieve continuous, on-chip separation of micro-/nanoparticles. This combined effect allows separation to reach the nanoscale and significantly sharpens the bands of the separated particles. We fabricated a three-dimensional (3D) serpentine-spiral microfluidic device by rolling a thin, flexible microfluidic chip around a cylindrical heating rod, which served as a radial heating source. By independently controlling the flow rate and electrical power, we regulated Dean flow-induced inertial effects and Joule heating-driven thermophoresis, creating a 3D serpentine-spiral and adjustable radial temperature (SART) device. Not only did we numerically simulate the SART device, but we also characterized it to optimize separation parameters for micro-/nanoparticles based on flow rate (inertia) and temperature gradient (thermophoresis). Our results demonstrated that the combined effects of inertia and thermophoresis significantly enhanced separation efficiency for a particle mixture containing microparticles (4.9, 3, and 1 μm) and nanoparticles (500, 380, and 200 nm). Furthermore, we applied the SART device to the separation of live microscale cells from their nanoscale debris, incorporating an in-line thermal cell lysis process. We believe that the 3D SART device can be further developed into a fully automated on-chip bioprocessing system by integrating additional physical fields and advancing microfabrication techniques.
芯片上的微/纳米颗粒分离是一个重要的研究领域，在生物学、生物医学工程和材料科学中具有重要应用。然而，传统的单场分离策略存在一定局限性，例如依赖颗粒性质、尺寸选择性以及可分离目标范围受限。通过结合互补的物理场可以克服这些局限性，这样每个单独场的优势能够弥补其他场的劣势。在本研究中，我们提出了一种基于多物理场（MPF）的方法，该方法协同结合惯性和热泳效应，以实现微/纳米颗粒在芯片上的连续分离。这种联合效应使分离能够达到纳米尺度，并显著锐化分离颗粒的条带。我们通过将薄的柔性微流控芯片围绕圆柱形加热棒滚动，制造了一种三维（3D）蛇形螺旋微流控装置，该加热棒作为径向热源。通过独立控制流速和电功率，我们调节了迪恩流诱导的惯性效应和焦耳热驱动的热泳，创建了一种3D蛇形螺旋且径向温度可调（SART）的装置。我们不仅对SART装置进行了数值模拟，还对其进行了表征，以基于流速（惯性）和温度梯度（热泳）优化微/纳米颗粒的分离参数。我们的结果表明，惯性和热泳的联合效应显著提高了含有微颗粒（4.9、3和1μm）和纳米颗粒（500、380和200nm）的颗粒混合物的分离效率。此外，我们将SART装置应用于从其纳米级碎片中分离活的微米级细胞，并纳入了在线热细胞裂解过程。我们相信，通过整合额外的物理场并推进微制造技术，3D SART装置可以进一步发展成为一个全自动化的芯片上生物处理系统。
