最灵敏的基于硅纳米线FET的DNA传感器在上海研究成功

上海微系统与信息技术研究所和上海应用物理研究所的2个研究小组最近在最新一期的Nano Letters上以快报形式报导了他们在超高灵敏硅纳米线DNA传感器方面的合作研究进展。     

氧化钨纳米线修饰多孔硅结构的制备及NO2气敏性能研究

针对多孔硅气敏传感器在室温下对NO2气体灵敏度较低、选择性不强的问题,采用双槽电化学腐蚀法制备多孔硅,然后在多孔硅顶部溅射沉积金属钨薄膜并经高温热处理氧化形成WO3纳米线,制备出WO3纳米线修饰多孔硅结构及其气敏传感器,对WO3纳米线/多孔硅材料进行了SEM和XRD分析,测试了传感器室温下对NO2的气敏特性。结果表明,制备WO3纳米线的最佳热处理条件是700℃,此温度下增加金属钨膜溅射时间可提升WO3纳米线的生长密度? 所制备的传感器对NO2气体表现出反型气敏响应,特别是溅射1min金属钨的样品显示出优异的NO2室温探测能力与选择性,对4×10-6NO的气敏灵敏度是单纯多孔硅样品的 5.8倍。     

基于BOE硅腐蚀现象的硅纳米线制作

介绍一种硅纳米线制作方法.在SOI顶层硅上制作硅纳米梁,通过离子注入形成pnp结构,利用新发现的没有特殊光照时BOE溶液腐蚀pn结n型区域现象,结合BOE溶液氧化硅腐蚀,实现硅纳米线制作.制作完全采用传统MEMS工艺,具有工艺简单,成本低,可控,可靠性好,可批量制作等优点.利用该方法制作出了厚50 nm,宽100 nm的单晶硅纳米线,制作的纳米线可用于一维纳米结构电学性能研究、谐振器研究等.     

多孔硅气体传感器

介绍了多孔硅气体传感器的原理和优点,综述了多孔硅气体传感器测量氮氧化物和几种有机气体的机理、方法及最新的研究进展,并分析了传感器的选择性和稳定性,展望了多孔硅气体传感器应用前景。     

一维纳米材料在气体传感器中的应用

评述了目前一维纳米材料在气体传感器中的应用进展.包括单壁碳纳米管、多壁碳纳米管、单根金属及金属氧化物纳米带或纳米线制作的传感器,这些传感器能在室温下检测,具有灵敏度高、漂移小的优点,但由于制作成本高昂、检测条件苛刻,离实用还很远.将氧化物一维纳米材料用于制作旁热式气敏元件,在保持其高灵敏度的同时提高稳定性,有助于解决旁热式气敏元件实用中存在的稳定性差的问题,将成为目前实用化研究的一个热点.     

基于Fano共振的全介质型超表面甲烷传感器设计

与传统甲烷传感器相比,超表面甲烷传感器具有高度灵敏、性能稳定、小型化、集成化、多功能可定制等优点,更满足在煤矿等复杂环境下的应用需求。设计了基于Fano共振的全介质型超表面甲烷传感器。超表面结构由周期性的硅纳米结构和SiO₂衬底组成,包含4个方形硅环纳米结构及中心的硅纳米方块。通过改变几何参数观察其对全介质超表面结构Fano共振的影响,结果表明,综合考虑结构的品质因数和调制深度,应选取方形硅环中心距离为1 000 nm,方形硅环的内边长为100 nm,硅纳米块的边长为200 nm,此时品质因数为227.60,调制深度为99.98%,接近100%。通过在超表面结构内涂覆甲烷气敏薄膜实现传感检测功能,结合极窄线宽的Fano谐振特性和显著的局域场增强效应,实现对甲烷气体的高精度检测。仿真结果表明：全介质超表面传感器对甲烷体积分数的灵敏度为-0.953 nm/%,且甲烷体积分数变化与共振峰偏移量呈线性关系,监测性能较好;全介质超表面传感器的折射率灵敏度高达883.95 nm/RIU,且共振峰偏移量与环境折射率增量呈线性关系,可用于检测环境折射率的变化。     

结合LAPS及纳米多孔硅的气体传感器研究#

结合光寻址电位传感器及纳米多孔硅技术研制了一种新型的气体传感器.该传感器结合光寻址电位传感器的微机电系统工艺和平面器件特点以及纳米多孔硅的高灵敏度特性,对实现进一步细胞代谢气体的检测提供了一种可能的手段.初步实验结果表明,在室温条件下,该气体传感器对于乙醇气体具有较明显的响应,并具有一定的浓度梯度特性,证明该传感器的设计是可行的.     

纳米生物传感器的研究进展

纳米生物传感器是纳米科技与生物传感器的融合,其研究涉及到生物技术、信息技术、纳米科学、界面科学等多个重要领域,并综合应用光声电色等各种先进检测技术,可能对临床检测、遗传分析、环境检测、生物反恐和国家安全防御等多个领域产生革命性的影响,因而成为国际上的研究前沿和热点。近年来,随着纳米科学与界面科学的蓬勃发展,纳米生物传感器引起了世人前所未有的极大关注,其开发迅猛,应用广阔。本文从纳米生物传感器的研究现状、应用和展望三方面对纳米生物传感器进行了综述,为了解纳米生物传感器的研究与应用提供帮助。     

基于Pd-Ni/Si Nanowires电极室内甲醛实时监测处理装置

研究设计一种室内甲醛气体实时监测和处理一体化装置。首先,通过电化学方法刻蚀大面积硅纳米线阵列并通过无电镀技术制备镍/硅纳米线(Ni/Si Nanowires)和钯-镍/硅纳米线(Pd-Ni/Si Nanowires)阵列电极,Pd-Ni/Si Nanowires阵列电极对甲醛有很强电化学催化氧化作用,以其为电化学甲醛传感器工作阳极,以Ni/Si Nanowires阵列为对电极,Ag/AgCl为参考电极,循环伏安技术测试结果显示该传感器对甲醛浓度灵敏度高达0.265 mA/(mmol/L),三倍信噪比检测限为2μmol/L。其次,利用STC12C5410AD单片机产生三角波扫描电压模拟循环伏安原理,可利用回路中因催化氧化产生的峰电流值来监测室内甲醛浓度,并进一步通过恒压电催化将甲醛处理。该设计方案新颖、成本低廉、便于携带,具有较大实际应用价值。     

本期摘要

纳米生物传感器的研究进展 作者张文毓 单位：中国船舶重工集团公司第七二五研究所．河南洛阳471023 摘要纳米生物传感器是纳米科技与生物传感器的融合．其研究涉及到生物技术、信息技术、纳米科学、界面科学等多个重要领域．并综合应用光声电色等各种先进检测技术．可能对临床检测、遗传分析、环境检测、生物反恐和国家安全防御等多个领域产生革命性的影响．因而成为国际上的研究前沿和热点。近年来．随着纳米科学与界面科学的蓬勃发展．纳米生物传感器引起了世人前所未有的极大关注,开发迅猛．应用广阔。从纳米生物传感器的研究现状、应用和展望三方面对纳米生物传感器进行了综述,为了解纳米生物传感器的研究与应用提供帮助。     

Component design and testing for a miniaturised autonomous sensor based on a nanowire materials platform

We present the design considerations of an autonomous wireless sensor and discuss the fabrication and testing of the various components including the energy harvester, the active sensing devices and the power management and sensor interface circuits. A common materials platform, namely, nanowires, enables us to fabricate state-of-the-art components at reduced volume and show chemical sensing within the available energy budget. We demonstrate a photovoltaic mini-module made of silicon nanowire solar cells, each of 0.5 mm² area, which delivers a power of 260 μW and an open circuit voltage of 2 V at one sun illumination. Using nanowire platforms two sensing applications are presented. Combining functionalised suspended Si nanowires with a novel microfluidic fluid delivery system, fully integrated microfluidic–sensor devices are examined as sensors for streptavidin and pH, whereas, using a microchip modified with Pd nanowires provides a power efficient and fast early hydrogen gas detection method. Finally, an ultra-low power, efficient solar energy harvesting and sensing microsystem augmented with a 6 mAh rechargeable battery allows for less than 20 μW power consumption and 425 h sensor operation even without energy harvesting.     

Tin-copper mixed metal oxide nanowires: Synthesis and sensor response to chemical vapors

Tin-copper mixed metal oxide nanowires were successfully prepared by thermally oxidizing electrodeposited metallic nanowires (Sn-8 at.% Cu, Sn-43 at.% Cu and Sn-86 at.% Cu). The structure and composition of these nanowires before and after thermal oxidation were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). Dielectrophoresis was utilized to align the nanowires in contact with pre-fabricated interdigitated electrodes to form a chemiresistive gas sensor circuit. The sensitivity variation of the nanowires with different compositions was tested with acetone, ethanol and ethyl acetate vapors at different concentration levels, and the temperature effect was studied at five operating temperatures, ranging from 200 °C to 440 °C. All the three mixed metal oxide nanowire sensors exhibited higher sensitivity than that of pure tin oxide nanowire sensor. The sensor performance was also investigated in terms of response/recovery time and repeatability. An interesting positive/negative response was observed by varying the element composition of the mixed oxide nanowires.     

Fabrication and characterization of a nanowire/polymer-based nanocomposite for a prototype thermoelectric device

This paper discusses the design, fabrication and testing of a novel thermoelectric device comprised of arrays of silicon nanowires embedded in a polymer matrix. By exploiting the low-thermal conductivity of the composite and presumably high-power factor of the nanowires, a thermoelectric figure of merit, higher than the corresponding bulk value, should result. Arrays were first synthesized using a vapor-liquid-solid (VLS) process leading to one-dimensional (1-D) growth of single-crystalline nanowires. To provide structural support while maintaining thermal isolation between nanowires, parylene, a low thermal conductivity and extremely conformal polymer, was embedded within the arrays. Mechanical polishing and oxygen plasma etching techniques were used to expose the nanowire tips and a metal contact was deposited on the top surface. Scanning electron micrographs (SEMs) illustrate the results of the fabrication processes. Using a modification of the 3/spl omega/ technique, the effective thermal conductivity of the nanowire matrix was measured and 1 V characteristics were also demonstrated. An assessment of the suitability of this nanocomposite for high thermoelectric performance devices is given.     

Humidity sensing behavior of silicon nanowires with hexamethyldisilazane modification

In this paper, the sensing behavior of the capacitive humidity sensors based on silicon nanowires with and without hexamethyldisilazane (HMDS) modification has been investigated. The sensing mechanism is based on the capacitance variations due to the adsorption/desorption of water molecules among silicon nanowires. The effect of HMDS modification on the sensor's performance was discussed. The study indicated that after HMDS treatment, the sensor's surface turns into hydrophobic and the sensor's performance such as the linearity, hysteresis and response time can be improved remarkably.     

Influence of morphology and structure geometry on NO2 gas-sensing characteristics of SnO2 nanostructures synthesized via a thermal evaporation method

SnO₂ microwires, nanowires and rice-shaped nanoparticles were synthesized by a thermal evaporation method. The diameters of microwire and nanowire were 2 μm and 50-100 nm, respectively, with approximately the same length (∼20 μm). The size of nanoparticles was about 100 nm. It was confirmed that the as-synthesized products have SnO₂ crystalline rutile structure. The sensing ability of SnO₂ particle and wire-like structure configured as gas sensors was measured. A comparison between the particle and wire-like structure sensors revealed that the latter have numerous advantages in terms of reliability and high sensitivity. Although its high surface-to-volume ratio, the nanoparticle sensor exhibited the lowest sensitivity. The high surface-to-volume ratio and low density of grain boundaries is the best way to improve the sensitivity of SnO₂ gas sensors, as in case of nanowire sensor which exhibited a dramatic improvement in sensitivity to NO₂ gas.     

Directed transport and location-designated rotation of nanowires using ac electric fields

The motion control of individual nanowires is essential for effective nanowire manipulation strategies. In this paper, we demonstrate a simple and general method to dynamically control the motion of a chemically untreated nanowire in a quadrupole electrode structure. The motion of single nanowires was determined by positive dielectrophoresis and orientational torque, which were induced by optionally exerting ac signals onto specific electrodes for regulating the electric field distribution in real time. A silver nanowire was guided to transform postures and transport directionally in a working regime of about 115 μm × 115 μm. The selected nanowire was then transported to a region of weak gradients and forced to rotate at the designated location subsequently. The behavior of the nanowires, including their posture, cornering time, linear displacement and location-designated rotation, was dynamically monitored and regulated. A simple analytical model was developed to derive the driving forces and torques on the nanowire.     

An analytical coupling coefficient for MEMS tunable silicon nanowire waveguide coupler devices

Silicon nanowire waveguides are promising for future integration of photonic circuits with silicon electronics. Electromechanical control of waveguide is also favorable for variable silicon nanowire waveguide devices. In this study, we investigated analytically the characteristics of a silicon nanowire waveguide coupler for electromechanical waveguide devices. The electric field of the silicon nanowire waveguide was enhanced by the high-index contrast. The enhanced electric field increased the coupling coefficient by a factor of 2.7 for a silicon waveguide of 400 nm in width and 260 nm in thickness compared with the approximation on the basis of low-index-contract. The analytically derived coupling coefficient was evaluated experimentally by investigating a waveguide coupler switch with a micro-electromechanical actuator.     

Seven strategies for tolerating highly defective fabrication

This article we present an architecture that supports fine-grained sparing and resource matching. The base logic structure is a set of interconnected PLAs. The PLAs and their interconnections consist of large arrays of interchangeable nanowires, which serve as programmable product and sum terms and as programmable interconnect links. Each nanowire can have several defective programmable junctions. We can test nanowires for functionality and use only the subset that provides appropriate conductivity and electrical characteristics. We then perform a matching between nanowire junction programmability and application logic needs to use almost all the nanowires even though most of them have defective junctions. We employ seven high-level strategies to achieve this level of defect tolerance.     

Fabrication of AFM probe with CuO nanowire formed by stress-induced method

A novel method has been proposed to fabricate an atomic force microscope (AFM) probe using CuO nanowire and a stress-induced method that can form the nanowire easily. By heating a commercial AFM probe with a film coating of Ta and Cu, a Cu hillock with CuO nanowires on its surface could be formed at the end of the probe. The thickness of the coating films, the heating temperature, and the heating time were investigated to obtain CuO nanowires with a high aspect ratio for use as an AFM probe tip. It was found that a suitable probe tip can be fabricated using the a Cu film thickness of 700 nm, a heating temperature of 380 °C and a heating time of 6 h. Probe tips (~5 μm high) and nanowires of ~25 nm diameter were obtained successfully. In the range evaluated, the measurement resolution of the CuO nanowire probe was slightly worse than that of a commercial AFM probe. However, both probes had almost the same dimensional measurement precision.