金刚石-碳化硅复合梯度薄膜驱动微流体的机理研究

Driving and control of microfluidics plays an important role in drug microinjection, micro-sized biosensor, and cooling system in integrated circuit. However, the traditional mechanical external force cannot meet the requirements of integration, low energy consumption and quick response. Without external energy, the fluids can be driven by a surface with gradually changing wettability. Further, previous studies indicate that the wettability and protein adsorption could be gradually changed along the length of the diamond/silicon carbide composite film with gradually changing surface chemistry, which shows potential for drug delivery and control of cell growth direction. Therefore, this proposed project is envisaged to study the effects of surface composition and roughness of diamond composite films on the wettability and fluid driving ability. Diamond-SiC composite gradient films with gradually changed composition and porous diamond films with gradually changing roughness will be synthesized. The surface chemistry will be modified on these films. The mechanisms of the effect of surface characteristics on the wettability and fluid driving will be systemically investigated. Compared with other gradient surface materials, these diamond composite films composed of diamond and silicon carbide possess high chemical stability, controllable surface chemistry and controllable roughness, and good biocompatibility. This project provides new strategies for applications of diamond in the biomedical, electrical and microfluidics fields, including a study of surface effects.

微流体驱动和控制在药物的微量注射、微型生物传感器、集成电路的冷却等领域中起到至关重要的作用，而传统的机械外力驱动方式难以满足集成化、能耗少、响应快的要求。在无外加能源的条件下，润湿性梯度变化的材料表面可驱动液体的流动。进一步研究表明：通过在样品长度方向逐渐改变金刚石-碳化硅复合薄膜的表面化学状态，亲疏水性和蛋白质在表面的吸引情况呈梯度变化，具有药物运输和控制细胞生长方向的潜力。为此，本项目提出研究金刚石复合薄膜的表面化学和粗糙度对润湿性和流体驱动的影响这一科学问题，通过制备表面成分梯度变化的金刚石-碳化硅复合薄膜和粗糙度连续变化的多孔金刚石薄膜，并对其进行表面改性，系统研究表面特征对润湿性和流体驱动的机理。与其它梯度材料相比，此金刚石复合薄膜具有化学稳定性高、表面化学和多孔性可控、生物相容性良好的特点，在生物医学、微电子及微流体器件领域具有很大潜力，同时为表面界面的研究提供新的策略。

微流体驱动和控制在药物的微量注射、微型生物传感器、集成电路的冷却等领域中起到至关重要的作用，而传统的机械外力驱动方式难以满足集成化、能耗少、响应快的要求。在无外加能源的条件下，润湿性梯度变化的材料表面可驱动液体的流动。本项目采用热丝化学气相沉积技术制备微米和纳米金刚石-碳化硅复合梯度薄膜，以及具有多尺度粗糙度的仿生的高疏水性微纳复合金刚石-碳化硅复合梯度薄膜，在无外力作用下，以表面能为驱动力，自行运输水和腐蚀性液体。薄膜表面由疏水性纯纳米金刚石逐渐转变为亲水性纳米碳化硅，水珠是通过从梯度膜含金刚石的疏水端运输到碳化硅亲水端。水珠的行驶距离和速度受表面成分变化和粗糙度变化的影响。水珠在纳米梯度表面的传输距离和速率高于微米梯度膜，采用仿生微纳结构进一步提高金刚石一侧的疏水角，进而提高了传输距离。由于金刚石和β-SiC具有化学惰性，实现了盐酸和氢氧化钠溶液的自驱动，可应用于微流体器件、DNA传感器和植入物性器件。另外，梯度膜还被用于加快海水淡化系统中的水冷凝速率和提高雾收集能力，且在腐蚀性液体和研磨性喷砂的严酷处理后，集水性能仍然保持不变，这表明其在微流体、海水淡化和雾收集方面具有很大的应用潜力。