Manipulation Of Nanowires Research Articles

Manipulation of a Single Metal Nanowire by an Unpolarized Gaussian Beam.

Optical manipulation of metal nanowires offers a promising route to building optoelectronic nanosystems, which remains a challenge because of their strong absorption or scattering properties. Here, precise optical manipulation of a single Ag nanowire, including capture, translation, rotation, immobilization, and release, was readily achieved within a large operation range of 100 μm by a single unpolarized Gaussian beam based on an optical scattering force. Besides, the optical forces and torques exerted on the Ag nanowires under different conditions were quantitatively analyzed and calculated by simulation to give insight into the manipulation mechanism. This proposed scattering-force-based optical manipulation method also has great position and orientation stability with a capture stiffness of 1.2 pN/μm and an orientation standard deviation of 0.3°. More surprisingly, it is independent of both laser polarization and the metal material, shape, and size and is a universal and promising strategy for the manipulation and assembly of nontransparent structures in mesoscopic/Mie sizes.

Optical trapping and manipulation of nanowires using multi-hotspot dielectric nanononamers

Semiconductor nanowires have demonstrated great potential in all-photonic integrated circuit applications. However, the development of a controllable multidimensional nanowire assembly technique is still arguably in its infancy. Here, we numerically demonstrate the optical trapping and manipulation of cylindrical zinc oxide nanowires using an all-dielectric silicon nanononamer for designing programmable nanolasers. The nanononamer is composed of nine identical silicon nanocylinders arranged in a square grid on top of a glass substrate. This is a suitable choice, as optical trapping with the proposed silicon nanononamer is envisioned as an effective technique for the contactless manipulation of suspended nanowires with multiple hotspots and with negligible heating generation. We determine optical forces and torques applied to nanowires using the Maxwell stress tensor method. We investigate the influence of light polarization on the field confining and laser tweezing properties. For this work, the simple nanowire-based silicon photonic platform is compatible with the complementary metal–oxide–semiconductor technology, which allows low-cost fabrication of such structures and the integration with other on-chip optical components.

Functional Devices from Bottom-Up Silicon Nanowires: A Review.

This paper summarizes some of the essential aspects for the fabrication of functional devices from bottom-up silicon nanowires. In a first part, the different ways of exploiting nanowires in functional devices, from single nanowires to large assemblies of nanowires such as nanonets (two-dimensional arrays of randomly oriented nanowires), are briefly reviewed. Subsequently, the main properties of nanowires are discussed followed by those of nanonets that benefit from the large numbers of nanowires involved. After describing the main techniques used for the growth of nanowires, in the context of functional device fabrication, the different techniques used for nanowire manipulation are largely presented as they constitute one of the first fundamental steps that allows the nanowire positioning necessary to start the integration process. The advantages and disadvantages of each of these manipulation techniques are discussed. Then, the main families of nanowire-based transistors are presented; their most common integration routes and the electrical performance of the resulting devices are also presented and compared in order to highlight the relevance of these different geometries. Because they can be bottlenecks, the key technological elements necessary for the integration of silicon nanowires are detailed: the sintering technique, the importance of surface and interface engineering, and the key role of silicidation for good device performance. Finally the main application areas for these silicon nanowire devices are reviewed.

Electric Field-Induced Phase Transition of Nanowires on Germanium(001) Surfaces.

The manipulation of conductive nanowires (NWs) on semiconductor platforms provides important insights into the fabrication of nanoscale electronic devices. In this work, we directly observed the electric field-induced phase transitions in atomic Au-NWs self-assembled on Ge(001) surfaces using scanning tunneling microscopy (STM). The tunneling electrons and electric fields underneath a STM tip apex can effectively trigger a phase transition in Au-NWs on Ge(001) surfaces. Such phase transitions are associated with a remarkable atomic rearrangement in the Au-NWs, thereby modifying their band structures. Moreover, directly monitoring the dynamic reconstruction of Au-NWs on Ge(001) surfaces helps us to understand the NWs' intricate atomic configurations and their electronic properties. The spatially controlled phase transition at the nanometer scale using STM shows the possibility of modulating NWs' properties at an atomic scale.

Magnetic Manipulation of Nanowires for Engineered Stretchable Electronics.

Nanowires are often key ingredients of high-tech composite materials. The properties and performance of devices created using these, depend heavily on the structure and density of the embedded nanowires. Despite significant efforts, a process that can be adapted to different materials, compatible with current nanowire deposition methods, and that is able to control both variables simultaneously has not been achieved yet. In this work, we show that we can use low magnetic fields (80 mT) to manipulate nanowires by electrostatically coating them with superparamagnetic iron oxide nanoparticles in an aqueous solution. Monolayers, multilayers, and hierarchical structures of oriented nanowires were achieved in a highly ordered manner using vacuum filtration for two types of nanowires: silver and gold-coated titanium dioxide nanowires. The produced films were embedded in an elastomer, and the strain-dependent electrical properties of the resulting composites were investigated. The orientation of the assembly with respect to the tensile strain heavily impacts the performance of the composites. Composites containing nanowires perpendicular to the strain direction exhibit an extremely low gauge factor. On the other hand, when nanowires are arranged parallel to the strain direction, the composites have a high gauge factor. The possibility to orient nanowires during the processing steps is not only interesting for the shown strain sensing application but also expected to be useful in many other areas of material science.

Optically Programmable Plateau-Rayleigh Instability for High-Resolution and Scalable Morphology Manipulation of Silver Nanowires for Flexible Optoelectronics.

The ability to engineer microscale and nanoscale morphology upon metal nanowires (NWs) has been essential to achieve new electronic and photonic functions. Here, this study reports an optically programmable Plateau-Rayleigh instability (PRI) to demonstrate a facile, scalable, and high-resolution morphology engineering of silver NWs (AgNWs) at temperatures <150 °C within 10 min. This has been accomplished by conjugating a photosensitive diphenyliodonium nitrate with AgNWs to modulate surface-atom diffusion. The conjugation is UV-decomposable and able to form a cladding of molten salt-like compounds, so that the PRI of the AgNWs can be optically programmed and triggered at a much lower temperature than the melting point of AgNWs. This PRI self-assembly technique can yield both various novel nanostructures from single NW and large-area microelectrodes from the NW network on various substrates, such as a nanoscale dot-dash chain and the microelectrode down to 5 μm in line width that is the highest resolution ever fabricated for the AgNW-based electrode. Finally, the patterned AgNWs as flexible transparent electrodes were demonstrated for a wearable CdS NW photodetector. This study provides a new paradigm for engineering metal micro-/nanostructures, which holds great potential in fabrication of various sophisticated devices.

Electrophoresis-Based Adaptive Manipulation of Nanowires in Fluid Suspension

Automated, highly precise online manipulation of nanoscale and microscale objects is essential to achieve scalable nanomanufacturing. However, nanoparticles and microparticles exhibit as yet unpredictable and, therefore, uncontrolled variations in their structures or compositions that can limit their functions and properties. In this article, we present an electric field-based adaptive manipulation scheme to precisely control the motion of individual nanowires, online estimate their unknown mobilities, and rapidly plan the desired trajectories with the estimated mobilities. The input saturation is considered in the adaptive controller, and the closed-loop system is proved to be asymptotically stable. The proposed motion planners (MPs), ${{\tt Bi}}$ - ${{\tt iSST}}$ s, are built on and extended by the stable sparse rapidly exploring random tree ( ${{\tt SST}}$ )-based kinodynamic motion-planning algorithms. Two sparse trees are maintained to increase the probability of finding a solution. The ${{\tt Bi}}$ - ${{\tt iSST}}$ algorithms use the workspace information, heuristics, and optimization to effectively guide the search process. When compared with the state-of-the-art algorithms, a ${{\tt Bi}}$ - ${{\tt iSST}}$ variant, the ${{\tt opt}}$ - ${{\tt Bi}}$ - ${{\tt iSST}}$ algorithm, quickly updates feasible solutions with the online estimated mobilities of multiple nanowires and converges to a near-optimal, minimum-time solution to increase the efficiency of simultaneous manipulation of the nanowires. Therefore, without complex characterization of each nanowire’s mobility, the nanowires can be steered simultaneously and efficiently to achieve precisely controlled positions without collisions. Simulation and experimental results confirm that the proposed integrated adaptive manipulation scheme precisely, independently, and simultaneously manipulates the motion of multiple nanowires.

Single GaAs nanowire based photodetector fabricated by dielectrophoresis

Mechanical manipulation of nanowires (NWs) for their integration in electronics is still problematic because of their reduced dimensions, risking to produce mechanical damage to the NW structure and electronic properties during the assembly process. In this regard, contactless NW manipulation based methods using non-uniform electric fields, like dielectrophoresis (DEP) are usually much softer than mechanical methods, offering a less destructive alternative for integrating nanostructures in electronic devices. Here, we report a feasible and reproducible dielectrophoretic method to assemble single GaAs NWs (with radius 35–50 nm, and lengths 3–5 μm) on conductive electrodes layout with assembly yields above 90% per site, and alignment yields of 95%. The electrical characteristics of the dielectrophoretic contact formed between a GaAs NW and conductive electrodes have been measured, observing Schottky barrier like contacts. Our results also show the fast fabrication of diodes with rectifying characteristics due to the formation of a low-resistance contact between the Ga catalytic droplet at the tip of the NW when using Al doped ZnO as electrode. The current-voltage characteristics of a single Ga-terminated GaAs NW measured in dark and under illumination exhibit a strong sensitivity to visible light under forward bias conditions (around two orders of magnitude), mainly produced by a change on the series resistance of the device.

Adaptive Tube Model Predictive Control for Manipulating Multiple Nanowires with Coupled Actuation in Fluid Suspension

Automated, highly precise online manipulation of multiple nano and microscale objects is essential to achieve scalable nanomanufacturing. One of the biggest limitations of the wireless external actuation is its global and coupled influence in the workspace, which limits the capability to robustly control multiple nano and microparticles independently and simultaneously. Another challenge for the highly precise manipulation of nanoparticles is due to their uncontrolled variations in structures or compositions that result in different dynamic behaviors. In this paper, we present an adaptive tube model predictive control scheme for the simultaneous manipulation of multiple nanowires under coupled electric fields in fluid suspension. The proposed strategy estimates the unknown mobilities of the individual nanowires online, formulates dynamic tubes that update based on the online estimated mobilities and nonlinear dynamics, and addresses the coupled actuation from the global electric field with dynamic separated tubes constructed for each nanowire. Simulations results show that as the number of simultaneously manipulated nanowires increases, the manipulation time increases and the maximum disturbance the system could reject decreases rapidly.

Nano-manipulation and nano-assembling using shape memory alloy nanogripper of metal oxide and semiconductor single nanowires and nanoparticles for biological nanosensors∗∗Report at 9th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2018), 7-11 November 2018, Ninh Binh City, Vietnam.

The nanomaterials based on metal oxides or semiconductor nanoparticles and nanowires appear to demonstrate the unique physical and also functional properties. Those properties, in general, allow constructing a large number of individual nanodevices for promising applications in nanoelectronics, photonics and biomedical technology. Such individual nanodevices represent interesting building blocks for new type of hierarchical mechanical nano-assembling. Mechanical hierarchical nano-assembly of functional nanoscale/meso-macroscale devices into macroscopic devices opens up the new perspectives for the creating of micro-meso and macro-devices and their arrays for many applications. The report describes the physical principle and design of the shape memory based nanogrippers as well as the preliminary results of the manipulation of CNTs, InP, ZnO nanowires and nanoparticles as building blocks for biomedical sensors.

Magnetic imaging of a single ferromagnetic nanowire using diamond atomic sensors

Recent advances in nanorobotic manipulation of ferromagnetic nanowires bring new avenues for applications in the biomedical area, such as targeted drug delivery, diagnostics or localized surgery. However, probing a single nanowire and monitoring its dynamics remains a challenge since it demands high precision sensing, high-resolution imaging, and stable operations in fluidic environments. Here, we report on a novel method of imaging and sensing magnetic fields from a single ferromagnetic nanowire with an atomic-scale sensor in diamond, i.e. diamond nitrogen-vacancy (NV) defect center. The distribution of static magnetic fields around a single Co nanowire is mapped out by spatially distributed NV centers and the obtained image is further compared with numerical simulation for quantitative analysis. DC field measurements such as continuous-wave ODMR and Ramsey sequence are used in the paper and sub Gauss level of field sensing is demonstrated. By imaging magnetic fields at a single nanowire level, this work represents an important step toward tracking and probing of ferromagnetic nanowires in biomedical applications.

Simultaneous Multiple-Nanowire Motion Control, Planning, and Manipulation Under Electric Fields in Fluid Suspension

To fully take advantage of the enormous potential of functional nanodevices, it is crucial to automate their manufacture with efficient steering and manipulation of multiple nanowires with controlled orientations to specific spatial locations. In this paper, we present motion planning and control algorithms for simultaneously steering multiple nanowires in liquid suspension. The motion planning and control is designed for a microfluidic device that is actuated by a simple generic set of electrodes. We first present a motion control algorithm to simultaneously steer multiple nanowires along different desired trajectories under controlled electrophoretic forces. A two-stage motion planning algorithm is then presented to generate the desired trajectory for each individual nanowire. Both numerical simulation and experimental results are presented to demonstrate the performance of the motion planning and control design using electric fields to simultaneously steer and manipulate multiple nanowires. Note to Practitioners —The automated steering and manipulation of multiple nanowires would enable the scalable assembly of nanodevices for a variety of applications. This paper presents an electric-field-based design for simultaneous motion planning and control of multiple nanowires in liquid suspension. The design uses a set of electrode arrays to drive and orient multiple nanowires from their starting locations to targeted locations under electrophoretic forces. The motion control of multiple nanowires in fluid suspension is first presented to steer the nanowires simultaneously along the given trajectories. Then, we present a two-stage motion planning algorithm to generate the total shortest distance trajectories for all nanowires while avoiding collision. We present extensive simulations and experiments to demonstrate the motion planning and control of multiple nanowires to form various geometric patterns. The results will help provide a foundation for scalable automated methods for manipulating nanowires to build nanodevices.

Automated characterization and assembly of individual nanowires for device fabrication.

The automated sorting and positioning of nanowires and nanotubes is essential to enabling the scalable manufacturing of nanodevices for a variety of applications. However, two fundamental challenges still remain: (i) automated placement of individual nanostructures in precise locations, and (ii) the characterization and sorting of highly variable nanomaterials to construct well-controlled nanodevices. Here, we propose and demonstrate an integrated, electric-field based method for the simultaneous automated characterization, manipulation, and assembly of nanowires (ACMAN) with selectable electrical conductivities into nanodevices. We combine contactless and solution-based electro-orientation spectroscopy and electrophoresis-based motion-control, planning and manipulation strategies to simultaneously characterize and manipulate multiple individual nanowires. These nanowires can be selected according to their electrical characteristics and precisely positioned at different locations in a low-conductivity liquid to form functional nanodevices with desired electrical properties. We validate the ACMAN design by assembling field-effect transistors (FETs) with silicon nanowires of selected electrical conductivities. The design scheme provides a key enabling technology for the scalable, automated sorting and assembly of nanowires and nanotubes to build functional nanodevices.

Direct observation of nanowire growth and decomposition

Fundamental concepts of the crystal formation suggest that the growth and decomposition are determined by simultaneous embedding and removal of the atoms. Apparently, by changing the crystal formation conditions one can switch the regimes from the growth to decomposition. To the best of our knowledge, so far this has been only postulated, but never observed at the atomic level. By means of in situ environmental transmission electron microscopy we monitored and examined the atomic layer transformation at the conditions of the crystal growth and its decomposition using CuO nanowires selected as a model object. The atomic layer growth/decomposition was studied by varying an O2 partial pressure. Three distinct regimes of the atomic layer evolution were experimentally observed: growth, transition and decomposition. The transition regime, at which atomic layer growth/decomposition switch takes place, is characterised by random nucleation of the atomic layers on the growing {111} surface. The decomposition starts on the side of the nanowire by removing the atomic layers without altering the overall crystal structure, which besides the fundamental importance offers new possibilities for the nanowire manipulation. Understanding of the crystal growth kinetics and nucleation at the atomic level is essential for the precise control of 1D crystal formation.

Electrorotation and Electroorientation of Semiconductor Nanowires.

A number of experimental studies have shown electric-field manipulation of nanowires dispersed in liquids. We demonstrate from first-principles that the electrical response of semiconductor nanowires in liquids must be described by considering, at least, two mechanisms for interfacial polarization: the classical Maxwell-Wagner interfacial polarization and the formation of an electrical double layer. We compare the theoretical predictions with our experimental data and with data published elsewhere and show that both mechanisms play an important role.

Strategies for the AFM-based manipulation of silver nanowires on a flat surface

Silver nanowires (Ag NWs) are a promising material for building various sensors and devices at the nanoscale. However, the fast and precise placement of individual Ag NWs is still a challenge today. Atomic force microscopy (AFM) has been widely used to manipulate nanoparticles, yet this technology encounters many difficulties when being applied to the movement of Ag NWs as well as other soft one-dimensional (1D) materials, since the samples are easily distorted or even broken due to friction and adhesion on the substrate. In this paper, two novel manipulation strategies based on the parallel pushing method are presented. This method applies a group of short parallel pushing vectors (PPVs) to the Ag NW along its longitudinal direction. Identical and proportional vectors are respectively proposed to translate and rotate the Ag NWs with a straight-line configuration. The rotation strategy is also applied to straighten flexed Ag NWs. The finite element method simulation is introduced to analyse the behaviour of the Ag NWs as well as to optimize the parameter setting of the PPVs. Experiments are carried out to confirm the efficiency of the presented strategies. By comprehensive application of the new strategies, four Ag NWs are continuously assembled in a rectangular pattern. This study improves the controllability of the position and configuration of Ag NWs on a flat substrate. It also indicates the practicability of automatic nanofabrication using common AFMs.

A novel ‘leadless’ dielectrophoresis chip with dot matrix electrodes for patterning nanowires

In this paper, we present a novel ‘leadless’ dielectrophoresis chip with dot matrix electrodes (LDME-DEP chip) fabricated by stacking three different functional layers. Our LDME-DEP chip excels mainly in two aspects: we for the first time applied the technique of separating the lead and the electrode pattern into two different layers to patterning nanowires which achieves continuous-area manipulation of nanowires without interference from the lead; the use of dot matrix electrodes makes the manipulation more flexible. We firstly detail the fabrication and working principle of our LDME-DEP chip and propose the scheme for washing away the nanowires with unsatisfactorily positioned postures. Then, nanowire patterning applications (e.g., letter E, square and long chain) under the combination of dielectrophoretic force and hydrodynamic force are carried out and the effect of frequency of the electric signal on assembling accuracy of nanowires is discussed.

In situ observation and thermal alloying induced shape manipulation of FIB-grown Pt composite nanowires

With the assistance of in situ heating techniques in the transmission electron microscope, the morphology change of the Pt nanowires which were deposited by focus ion beam has been monitored under different temperatures. With a drastic shape expansion, a significant bending has been observed abruptly above 250°C. The energy dispersive X-ray spectroscopy mapping indicated the asymmetrical distribution of carbon (C), platinum (Pt) and gallium (Ga) within the Pt nanowires while the diffraction analysis revealed the crystalline formation of Ga-Pt alloys during the heating process. The in-situ exploration discovered that besides the recrystallization of Pt nanoparticles, the asymmetrical volume expansion from the Ga-Pt alloys formation should be another factor which induces the shape variation of the heated Pt nanowires.

Synthesis and surface plasmonic properties of ultra-thick silver nanowires

Metallic nanowires (NWs) possess significant potential for applications in integrated photonic and electronic devices at the nanoscale. Considering the manipulation of NWs and energy loss associated with surface plasmon polaritons (SPPs) modes which serve as signal carriers in the nanophotonic devices, NWs with large diameters are significant. In this work, we report a successive multi-step polyol process approach for the synthesis of ultra-thick silver nanowires (Ag NWs) and investigate their energy loss. Thin Ag NWs prepared in the first step are used as seeds for the further growth of thick Ag NWs in the subsequent steps, where Ag NWs with diameter as large as 1820 nm have been prepared. We further investigate the SPP propagation properties of these thick Ag NWs, and find that energy loss is decreased in Ag NWs with improved diameter. Our experimental results are important for the design and fabrication of SPP-based nanophotonic components and circuits.

In-plane trapping and manipulation of ZnO nanowires by a hybrid plasmonic field.

In general, when a semiconductor nanowire is trapped by conventional laser beam tweezers, it tends to be aligned with the trapping beam axis rather than confined in the horizontal plane, and this limits the application of these nanowires in many in-plane nanoscale optoelectronic devices. In this work, we achieve the in-plane trapping and manipulation of a single ZnO nanowire by a hybrid plasmonic tweezer system on a flat metal surface. The gap between the nanowire and the metallic substrate leads to an enhanced gradient force caused by deep subwavelength optical energy confinement. As a result, the nanowire can be securely trapped in-plane at the center of the excited surface plasmon polariton field, and can also be dynamically moved and rotated by varying the position and polarization direction of the incident laser beam, which cannot be performed using conventional optical tweezers. The theoretical results show that the focused plasmonic field induces a strong in-plane trapping force and a high rotational torque on the nanowire, while the focused optical field produces a vertical trapping force to produce the upright alignment of the nanowire; this is in good agreement with the experimental results. Finally, some typical ZnO nanowire structures are built based on this technique, which thus further confirms the potential of this method for precise manipulation of components during the production of nanoelectronic and nanophotonic devices.