Novel DNA-Templated Nanotechnology Devices

目的本项目的主要目的是使用新型半导体材料制备晶体管和传感器等器件，该材料是通过包覆长而细的分子模板(DNA)来制备的，以便形成直径为几纳米-纳米线的导线。一纳米是十万分之一厘米，DNA双螺旋直径约为2纳米。DNA也是一种相对坚硬的分子，如果包裹DNA的材料要采取长而细的金属丝的形式，这是必不可少的。DNA模板法的其他优点来自于这样一个事实，即DNA是水溶性的，包覆这些分子所需的化学物质是温和的，并且在常温下在水溶液中发生。事实上，在水溶液中制备的纳米线可以很容易地转化为墨水，通过喷墨打印技术可以用来制造电子产品。该项目的目标是：1.在DNA模板上制备一系列半导体纳米线。制备水性纳米线油墨，并将其用于印刷电子设备。为了评估由DNA模板纳米线制备的晶体管的电性能。方法和方法该项目将以实验室为基础，使用各种制备和表征方法。DNA模板纳米线可以用金属硫化物(MS)或导电聚合物(CP)以不同的方式制备。硫化镉(CDS)将是本项目研究中使用的主要半导体；它是在DNA存在的情况下，通过使用硫化物沉淀镉盐的水溶液来制备的。在没有DNA的情况下，CDS以粒子的形式形成，但在适当的条件下，CDS将以导线的形式在DNA分子上形成。导电聚合物，如聚吡咯，可以通过三氯化铁氧化水溶液中的单体(重复单元)而形成。纳米线将使用UV-Vis吸收和原子力显微镜(AFM)等方法进行表征，以确定纳米线的尺寸和组成。到目前为止，对于这种类型的纳米线，只记录了使用两个触点在固定施加电压下的简单电流测量，该项目的目标是开发生产晶体管所需的方法，这些晶体管需要在每条纳米线上施加三个触点。第三个触点将充当闸门，调节其他两个触点之间的电流流动。将进行必要的化学、喷墨打印和洁净室技术方面的培训，以使用光刻和金属沉积从纳米线生产3个终端设备。然后，这些设备将使用探针站进行测试，以评估它们作为晶体管的性能。除了硫化镉(CDS)，还有其他很有前途的半导体材料可以在水溶液中用DNA制备。已知许多具有半导体性质的金属硫化物，这些金属硫化物可以通过在DNA存在的情况下从含水的金属盐中沉淀金属硫化物来产生。其他有趣和有前途的半导体材料包括碲化铋(Bi2Te3)，因为它的带隙很窄，只有0.21 eV。使用DNA模板铜纳米线的电流位移将其模板化到DNA上是可能的，然而尚未有电学测量的报道。所制备的Bi2Te3纳米线的表征将使用AFM以及能量色散X射线光谱(EDX)和光电子能谱来确定它们的化学成分。铋化合物对制造技术特别有意义，因为它们通常是无毒的，对环境有利。在进行了足够的电气测试后，Cd和Bi2Te3 NW将被改装成使用水和乙二醇混合物的墨水。墨水必须能够通过喷墨打印机中的喷嘴，这意味着必须优化某些特性，如粘度。

Aims The main aim of this project is the preparation of devices such as transistors and sensors using novel semiconducting materials prepared by coating a long thin molecular template (DNA) in order to form wires with a diameter on the scale of a few nanometres - nanowires. A nanometer is a 10-millionth of a centimetre and the DNA double helix is about 2 nm in diameter. DNA is also a relatively stiff molecule, which is essential if the material coating the DNA is to take the form of a long, thin wire. Other advantages to DNA-templating methods derive from the fact that DNA is water soluble and the chemistry required to coat these molecules is mild and takes place at ambient temperature in aqueous solution. Indeed, nanowires prepared in aqueous solution may be readily converted into inks that can be used to create electronics by inkjet printing technology. The project aims are:1. To prepare a range of semiconducting nanowires on DNA templates.2. To prepare aqueous nanowire inks and use these to print electronic devices.3. To assess the electrical performance of transistors prepared from DNA-templated nanowires.Methodology and ApproachThe project will be laboratory based with various preparation and characterisation methods being utilized. DNA-templated nanowires can be prepared in various ways using both metal sulfides (MS) or conducting polymers (CP). Cadmium sulphide (CdS) will be the main semiconductor studied used during this project; it is prepared by precipitation of an aqueous solution of a cadmium salt using sulfide-in the presence of DNA. In the absence of DNA, the CdS forms as particles, but under appropriate conditions, the CdS will form on the DNA molecules as a wire. Conductive polymers, such as polypyrrole, can be formed by oxidation of the monomer (repeat unit) in aqueous solution by ferric chloride.The nanowires will be characterised using methods such as UV-Vis absorption and atomic force microscopy (AFM) to confirm the size and composition of the nanowires. To-date only simple measurements of current at fixed applied voltage using two contacts have been recorded for this type of nanowire and the project aims to develop the methods required to produce transistors that require three contacts to be applied to each nanowire. The third contact will act as a gate to regulate the flow of current between the other two. Training will take place in the necessary chemical, inkjet printing and clean-room techniques to produce 3 terminal devices from the nanowires using photolithography and metal deposition. These devices will then be tested using a probe station to evaluate their performance as transistors. In addition to cadmium sulfide (CdS), there are other promising semiconductor materials that can be prepared on DNA in aqueous solutions. Many metal sufides with semiconductive behaviour are known and these may be produced by precipitating the metal sulfide from an aqueous metal salt in the presence of DNA. Other interesting and promising semiconducting materials include bismuth telluride (Bi2Te3) due to its narrow band gap of 0.21 eV. Templating this onto DNA is possible using galvanic displacement of DNA templated copper nanowires, however no electrical measurements have yet been reported. Characterisation of the prepared Bi2Te3 nanowires will involve AFM as well as energy-dispersive X-ray spectroscopy (EDX) and photoemission spectroscopy to confirm their chemical composition. Bismuth compounds are of particular interest for manufacturing technology because they are often non-toxic and are environmentally benign.After sufficient electrical testing has taken place the CdS and Bi2Te3 NW's will then be adapted to form an ink using a mixture of water and ethylene glycol. Inks must be able to pass through the jets in an inkjet printer meaning that certain properties must be optimised such as viscosity.