Volkmar Eichhorn

A carbon nanofibre scanning probe assembled using an electrothermal microgripper

Functional devices can be directly assembled using microgrippers with an in situ electron microscope. Two simple and compact silicon microgripper designs are investigated here. These are operated by electrothermal actuation, and are used to transfer a catalytically grown multi-walled carbon nanofibre from a fixed position on a substrate to the tip of an atomic force microscope cantilever, inside a scanning electron microscope. Scanning of high aspect ratio trenches using the nanofibre supertip shows a significantly better performance than that with standard pyramidal silicon tips. Based on manipulation experiments as well as a simple analysis, we show that shear pulling (lateral movement of the gripper) is far more effective than tensile pulling (vertical movement of gripper) for the mechanical removal of carbon nanotubes from a substrate.

Rapid prototyping of nanotube-based devices using topology-optimized microgrippers

Nanorobotic handling of carbon nanotubes (CNTs) using microgrippers is one of the most promising approaches for the rapid characterization of the CNTs and also for the assembly of prototypic nanotube-based devices. In this paper, we present pick-and-place nanomanipulation of multi-walled CNTs in a rapid and a reproducible manner. We placed CNTs on copper TEM grids for structural analysis and on AFM probes for the assembly of AFM super-tips. We used electrothermally actuated polysilicon microgrippers designed using topology optimization in the experiments. The microgrippers are able to open as well as close. Topology optimization leads to a 10-100 times improvement of the gripping force compared to conventional designs of similar size. Furthermore, we improved our nanorobotic system to offer more degrees of freedom. TEM investigation of the CNTs shows that the multi-walled tubes are coated with an amorphous carbon layer, which is locally removed at the contact points with the microgripper. The assembled AFM super-tips are used for AFM measurements of microstructures with high aspect ratios.

NanoLab: A nanorobotic system for automated pick-and-place handling and characterization of CNTs

Carbon nanotubes (CNTs) are one of the most promising materials for nanoelectronic applications. Before bringing CNTs into large-scale production, a reliable nanorobotic system for automated handling and characterization as well as prototyping of CNT-based components is essential. This paper presents the NanoLab setup, a nanorobotic system that combines specially developed key components such as electrothermal microgrippers and mobile microrobots inside a scanning electron microscope. The working principle and fabrication of mobile microrobots and electrothermal microgripper as well as their interaction and integration is described. Furthermore, the NanoLab is used to explore novel key strategies such as automated locating of CNTs for pick-and-place handling and methods for electrical characterization of CNTs. The results have been achieved within the framework of a European research project where the scientific knowledge will be transfered into an industrial system that will be commercially available for potential customers.

Multimodal Electrothermal Silicon Microgrippers for Nanotube Manipulation

Microgrippers that are able to manipulate nanoobjects reproducibly are key components in 3-D nanomanipulation systems. We present here a monolithic electrothermal microgripper prepared by silicon microfabrication, and demonstrate pick-and-place of an as-grown carbon nanotube from a 2-D array onto a transmission electron microscopy grid, as a first step toward a reliable and precise pick-and-place process for carbon nanotubes.

Nanorobotic manipulation setup for pick-and-place handling and nondestructive characterization of carbon nanotubes

A nanorobotic manipulation setup for the handling and characterization of carbon nanotubes (CNTs) is presented. The nanorobotic setup can be integrated into a scanning electron microscope (SEM) and various endeffectors may be attached to the manipulator either for CNT handling or characterization. The pick-and-place task is carried out by using an electrothermal actuated microgripper, designed for controlled manipulation of nanotubes. The nanotube is picked up from an array of multiwalled carbon nanotubes (MWCNTs) and transferred to the tip of an atomic force microscope (AFM) probe in order to assemble a high-aspect ratio AFM supertip. Another application of the nanorobotic setup considered in this paper is the nondestructive mechanical characterization of CNTs. A piezoresistive AFM probe is used to bend MWCNTs, while the bending force is measured, in order to estimate the Youngs modulus of the investigated MWCNTs.

Combined nanorobotic AFM/SEM system as novel toolbox for automated hybrid analysis and manipulation of nanoscale objects

In this paper, the concept and first results of a novel toolbox for nanoscale characterization are presented. A nanorobotic AFM system is being developed and integrated into a high resolution SEM/FIB system allowing nanoanalysis, -manipulation and -structuring. The compact and modular AFM setup enables probe- as well as sample-scanning and uses self-sensing AFM cantilevers. Image fusion algorithms are developed to merge SEM and AFM information for hybrid analysis of nanoscale objects. A commercial AFM controller is embedded into a special control system architecture that allows for automation of nanomanipulation sequences.

Nanohandling automation: Trends and current developments

Automated robot-based nanomanipulation is one of the key challenges in microsystem technology and nanotechnology, which has recently been addressed by a rising number of R&D groups and companies all over the world. Controlled, reproducible assembly processes at the nanoscale will enable high-throughput manufacturing of revolutionary products and open up new application fields. The ultimate goal of these research activities is the development of automated nanomanipulation processes to build a bridge between existing precise handling strategies for micro and nanoscale objects and aspired high-throughput fabrication of microsystems and nanosystems. Despite the growing interest in automated nanomanipulation, there is hardly any publication that treats this research in a coherent and comprehensive way. This paper is an attempt to provide the researcher with an overview of the most important trends and developments in this rapidly expanding technology. It also informs the practising engineer and the engineering student about automation at the nanoscale level as well as about the promising fields of application. The latter can be of a very different nature as nanohandling is strongly interdisciplinary in character. This paper offers a deeper insight into nanohandling aspects of carbon nanotubes.

Nanorobotic Assembly and Focused Ion Beam Processing of Nanotube-Enhanced AFM Probes

In this paper, a focused ion beam processing technique is presented that facilitates the modification of carbon nanotubes (CNTs) in terms of length, diameter, and orientation. The CNTs are mounted onto an atomic force microscope (AFM) probe by using a nanorobotic microgripper-based pick-and-place handling strategy. Such CNT-enhanced AFM probes are needed for metrology measurements of nanostructures with critical dimensions and high aspect ratios. The complete process of assembly and processing is realized inside a nanorobotic dual beam scanning electron microscope (SEM) and focused ion beam (FIB) machine.

Automated nanorobotic handling of bio- and nano-materials

Automated handling on the nanoscale is a crucial challenge for commercialization of bio- and nano-technologies. This paper describes current implementations towards two fields of application: Micro-nano integration for NEMS prototyping, and biosensor development. (1) The integration of nanomaterials into micro-systems can improve the properties of such systems and enable novel innovative solutions. Using nanorobotic systems operating inside the vacuum chamber of a scanning electron microscope is a promising approach. Nanorobotic strategies for the microgripper-based handling with focus on automation are presented. A fully automated handling sequence demonstrates the micro-nano integration of prototypic nanotube-enhanced atomic force microscope probes. (2) Nanorobotic systems employing an atomic force microscope are a promising approach for the handling of nanoscopic biomaterials. Methods for the handling of DNA to design bio-nano chips and to solve packaging problems on the nanoscale are presented. Additionally, an AFM-based approach for the structuring of biomaterials is presented.

Mechanical properties of boron nitride nanocones

Using classic molecular dynamics simulation, the mechanical properties of boron nitride nanocones (BNNCs) have been systematically investigated. The influences of the apex angle, cone height on tensile, and compressive behavior of BNNCs under axial strains are analyzed. The failure strains and strain energy per atom of BNNCs decrease with the increasing cone height, whereas the failure forces almost remain constant for BNNCs under axial tensile strains. For the buckling analyses of BNNCs, the critical strain and critical axial force reduce significantly with the increase of the apex angle. The increasing cone height can also significantly decrease the critical strain of BNNCs and only slightly affects the critical force of BNNCs. The cone height has little influence on the resulting buckling patterns; however, the apex angle has a significant effect on the buckling patterns of the BNNCs. From the computational analyses, it is noted that there exist three deformation patterns, i.e., fourfold rotational sym...