Novel DNA-Templated Nanotechnology Devices

该项目的主要目的是利用新型半导体材料制备晶体管和传感器等器件，通过涂覆长而薄的分子模板（DNA）来形成直径在几纳米尺度上的线-纳米线。一纳米是一厘米的千万分之一，DNA双螺旋的直径约为2纳米。DNA也是一种相对坚硬的分子，如果要让包裹DNA的材料形成又长又细的金属丝，这一点至关重要。DNA模板方法的其他优点源于DNA是水溶性的，覆盖这些分子所需的化学反应是温和的，并且在室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油墨，通过喷墨打印技术可以用于制造电子产品。该项目的目标是：1。在DNA模板上制备一系列半导体纳米线。制备水纳米线油墨，并将其用于印刷电子设备。评估dna模板纳米线制备的晶体管的电性能。该项目将以实验室为基础，采用各种制备和表征方法。采用金属硫化物（MS）或导电聚合物（CP）制备dna模板纳米线的方法多种多样。硫化镉（cd）将是本项目研究使用的主要半导体；它是在DNA存在的情况下，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会形成颗粒，但在适当的条件下，CdS会在DNA分子上形成导线。导电聚合物，如聚吡咯，可通过氯化铁氧化水溶液中的单体（重复单元）而形成。纳米线将使用紫外-可见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。迄今为止，这种类型的纳米线只记录了在固定施加电压下使用两个触点的简单电流测量，该项目旨在开发生产晶体管所需的方法，该方法需要在每个纳米线上应用三个触点。第三个触点将充当门，以调节其他两个触点之间的电流流动。将进行必要的化学、喷墨印刷和洁净室技术培训，以便利用光刻和金属沉积技术从纳米线生产3个终端设备。然后，这些器件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（cd）之外，还有其他有前途的半导体材料可以在水溶液中的DNA上制备。许多具有半导电行为的金属硫化物是已知的，它们可以通过在DNA存在下从含水金属盐中沉淀金属硫化物而产生。其他有趣和有前途的半导体材料包括碲化铋（Bi2Te3），因为它的窄带隙为0.21 eV。利用DNA模板铜纳米线的电位移将其模板化到DNA上是可能的，但是目前还没有电测量的报道。制备的Bi2Te3纳米线的表征将涉及原子力显微镜以及能量色散x射线光谱（EDX）和光发射光谱来确认其化学成分。铋化合物对制造技术特别感兴趣，因为它们通常无毒且对环境无害。在进行了充分的电气测试之后，CdS和Bi2Te3 NW将使用水和乙二醇的混合物制成墨水。油墨必须能够通过喷墨打印机的喷嘴，这意味着某些特性必须得到优化，比如粘度。

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.