基于介孔硅固定载体生物传感用微/纳悬臂梁力学行为和界面吸附特性研究

With the increasing requirement of detection sensitivity of biosensors based on micro/nano cantilevers, mesoporous materials have been used as the immobilization carrier for sensitive biomolecules. However, the influences of the structural parameters of mesoporous materials, size effect, surface and interface effects on the mechanical properties and the sensitivity characteristics of the cantilevers with mesoporous materials as the immobilization carrier have been still unclear so far. Furthermore, the understanding on the adsorption properties of sensitive biomolecules at the nanoscale interface is still poor. These gradually become the bottleneck of the development and the broad application of this kind of biosensing technique. For this problem, firstly, theoretical simulation together with auxiliary experiments will be conducted in this project to investigate the mechanical properties, e.g., elastic modulus, internal stress and interfacial cohesion, of the mesoporous silicon film/crystalline silicon cantilever system with different structural parameters. Moreover, the surface stress, lattice deformation and the damage mechanism under external loading will be analyzed. Meanwhile, the influencing behaviors and mechanisms of the mechanical properties of mesoporous silicon due to size effect, surface and interface effects will be examined. The diffusion and adsorption behaviors of sensitive biomolecules at the nanoscale interface in mesoporous silicon films will be investigated. The effect of the structural parameters of mesoporous silicon on the activity and stability of adsorbed biomolecules will be examined. Based on the previous results, mesoporous silicon/crystalline silicon cantilever system with optimized structural parameters will be fabricated, and their performances will be characterized. Theoretical bases and technical supports will be provided for the design and fabrication of nanoscale biosensors through the study of this project.

随着对微/纳悬臂梁生物传感器灵敏度要求的提高，介孔材料开始被用作固定敏感性生物分子的载体。但是目前，介孔材料结构参数及尺度效应、表界面效应等对微/纳悬臂梁力学性能等的影响规律和机制尚不明确，且人们对纳米界面上敏感性生物分子的吸附特性也没有清楚的认识，限制了此类生物传感技术的发展和推广应用。针对上述问题，本项目采用理论模拟为主辅以实验的方法，首先考察微尺度下具有不同结构参数的介孔硅膜/晶体硅微/纳悬臂梁体系的弹性模量、内应力等力学性能，以及在外载荷作用下的表面应力、晶格变形和损伤机制；揭示尺度效应和表界面效应对其力学性能的影响规律和机制。其次考察敏感性生物分子在介孔硅纳米界面的扩散和吸附行为，得到介孔硅结构参数等对分子吸附活性和稳定性的影响规律。最后制备具有优化结构参数的介孔硅膜/晶体硅悬臂梁，并对其性能进行测试。本项目的研究将为未来纳米尺度生物传感器的设计制造提供必要的理论基础和技术支持。

介孔硅具有比表面积大、表面反应活性高、催化效率高和吸附能力强等特征，将其应用于生物传感器能够极大改善传感器的性能。本项目针对介孔硅膜作为固定载体的微/纳悬臂梁体系，研究了纳米尺度介孔硅/晶体硅基底微/纳悬臂梁体系力学行为，分析了孔径、孔隙率和孔分布密度等对介孔硅力学性能的影响规律。结果表明：在相同孔径下，随着孔隙率（P）的增大，体模量、剪切模量和弹性模量都呈现减小的趋势，约化弹性模量和（1 - P）呈现二次曲线关系；当介孔间距相同时，孔径越大，介孔硅基体的弹性模量越小；反之相反。当介孔硅的孔半径相同时，随着介孔间距的增大，介孔硅基体的弹性模量增大。本项目考察了介孔硅的存在对悬臂梁体系静态变形量和残余应力的影响，结果发现，介孔硅的存在引入非常小的初始弯曲，介孔硅悬臂梁中的残余应力非常小，因此介孔硅悬臂梁体系残余应力对后续测量精度的影响很小。. 本项目研究了介孔硅的结构参数与敏感性生物分子扩散、吸附过程的内在联系。首先研究了氯酚分子在晶向结构不同的的多孔硅膜表面的吸附过程，氯酚分子的运动以垂直于界面的弛豫运动为主并发生了绕自身轴线的旋转运动，氯酚分子较长的轴近似平行于多孔硅表面。氯酚在Si(100)多孔硅膜界面的吸附能最小，氯酚在Si(111)多孔硅膜界面的吸附能最大。因此，在Si(111)晶向的硅片表面加工出的介孔硅结构具有更大的内表面积，并且具备更强的吸附生物分子的能力，使检测信息量大幅度增加，显著提高检测灵敏度。. 立足理论分析，优化介孔硅作为固定载体的微/纳悬臂梁结构参数，采用电化学刻蚀法处理得到多孔硅表面，检测结果显示多孔硅的孔径随腐蚀时间的增加而增大，多孔硅孔隙率随着腐蚀时间的增加呈现先增加后趋于稳定的趋势。通过本项目的研究，为未来介孔材料作为固定载体的微/纳悬臂梁式生物传感器设计制造提供必要的理论基础和技术支持。