基于一维纳米间隙电极约束组装的气敏传感器纳米线原位成形技术研究

As typical nanomaterials, 1-D nanostructures or nanowires are characterized by unique physical and chemical properties that differ from their macroscopic counterparts and, in particular, by an enhanced chemical reactivity even at room temperature. This effect has stimulated the development of high-sensitive gas sensors. However, it is worth noting that none of nanowire nanosensors has yet emerged as commercially valuable. As an experimental approach, nanowire nanosensors are commonly fabricated by placing the sensitive nanowires on prepatterned electrodes. The existence of possible technological constraints intrinsically in this method limits the commercialization of saleable gas nanosensors: Firstly, sensitive nanowires must be prepared before placing it on prepatterned electrodes. Thus, if some sensitive materials do not form nanowire, this method will become invalid. Secondly, connecting the nanowires to the electrodes or creating functional heterostructures and interfaces between the nanoire and the electrodes by mechanical gripping, alignment and assembly of nanowires will be a very difficult work. An AFM (atomic force microscope) has to be used in the above processes, which results in a low efficiency. .Actually, there exists another fabrication approach, although discussed in an only limited number of papers. It is the so-called "growth in place" technique that allows fabrication of the nanowire exactly where the nanosensor device architecture requires it, strongly simplifying the process and avoiding excessive handling of the nanowire. In this project, a novel nanowire in-situ growth technology based on nanogap electrode controlled dielectrophoretic assembly is proposed to fabricate high sensitive nanowire nanosensor. In this method, low energy electron beam induced expansion of polymer is used to provide stress for junction breaking in nanogap electrode fabrication processes. By controlling the irradiation area of electron beam, a large array of nanogap electrodes can be formed simultaneously. Nanogap planer electrode with tens of nanometers can form a large local electric field gradient, which generates a strong electrophoresis force and induces rapid assembly of nanopartcle along the direction of nanogap. The assemble nanoparticles will form nanowire in situ eventually. This nanowire nanosensor fabrication method avoid limits in the nanowires gripping, alignment and assembly method, and can form any nanowire structures for high performance integrated sensor at room tempreture. Research contents in this project include: expansion and fracture mechanism of polymer/metal film system under irradiation of low energy electron beam, characteristics of nanopartical dielectrophoretic assembly under the nanogap electric field, and the influence of nanowire characteristics on the sensor performance. This project aims to develop a novel nanowire in-situ forming method, which can fabricate the nanowire nanosensor cost-efficiently.

针对高性能纳米线气体传感器规模化制造的难题，本项目提出一种基于一维纳米间隙电极介电泳约束组装的气敏传感器纳米线原位成形技术。该技术利用聚合物材料在低能电子束照射条件下精确可控的伸展特性，采用隧道结应力断裂法实现一维纳米间隙电极的大面积并行制造；并利用一维纳米间隙电极在局部空间形成的强电场梯度，通过气体敏感纳米粒子的介电泳力约束组装，在间隙结构内原位实现传感器纳米线的高效精确成形。该技术克服了现有传感器实验制备过程中因依赖纳米线机械操纵方法而存在的局限性和效率问题，可在室温、常压条件下形成高性能集成传感器所需要的任意纳米线结构。本项目将在低能电子束照射下聚合物/金属双层膜系的延展断裂机理、纳米间隙电极约束条件下气体敏感粒子的介电泳组装行为、纳米线的组装方式对传感器性能的影响规律等三个方面探索基础理论，解决其中涉及的关键技术难题，从而为高性能纳米线气体传感器的高效制造发展一种原创性的工艺方法。

纳米线传感器的优异特性吸引了广泛的研究，然而纳米缝电极的可控制造以及纳米线的原位精确成形问题是制约此类传感器规模化制造的重要瓶颈。因此，要支撑高灵敏度纳米线传感器的发展，就必须探索符合规模化制造技术内涵的纳米间隙电极和纳米线原位成形技术。本项目从纳米缝电极的制造工艺和低维材料的自组装成形机理出发，研究了基于纳米线原位成形的柔性纳米传感器，解决了高性能集成纳米线传感器的制造难题，形成了独立自主的知识产权。. 在纳米缝电极的可控制造方面，本项目提出了低能电子束照射聚合物延展制备纳米间隙电极的制造技术，聚合物溶胀法制备纳米间隙电极的制造技术以及复杂曲面柔性纳米间隙电极的制造技术，该类工艺方法解决了传统纳米间隙电极制造方法成本高、效率低、不易于批量化生产等问题，为纳米间隙电极的可控制造提供了新的思路；. 在低维材料介电泳组装行为方面，本项目对纳米粒子方面，研究了宽频交流电场的纳米粒子链成形的频率特性，建立了考虑粒子/电解质界面和电极/电解质界面的电场诱导双电层极化的理论模型，分析了纳米粒子线的频域生长特性；针对纳米线方面，研究了纳米线介电泳组装的成形规律，探索了交流电场的频率、电压以及组装时间对纳米线组装结果的影响规律。该方面的研究工作建立了低维材料介电泳自组装的动力学行为规律，不仅限于本项目探讨的金纳米粒子和碳纳米管，亦适用于其他功能性低维材料，为低维材料的自组装结构化提供了理论基础；. 在柔性纳米传感器制造方面，本项目以紫外光和pH值为检测对象，基于功能化氧化锌纳米粒子和羧基功能化单壁碳纳米管，通过介电泳组装在柔性纳米间隙电极实现了柔性紫外传感器和化敏电阻器型pH传感器，其在响应特性、可逆性、可重复性、线性传感范围以及柔性性能方面具有突出的优势。本项目提出的柔性纳米传感器制造技术根据敏感低维材料的不同可广泛推广于氢气、氨气以及红外光检测等方面，为纳米传感器的应用推广提供了可行的制造方法。