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J Microsc ; 248(2): 163-71, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23078116


One of the most challenging issues faced in handling specimens for microscopy, is avoiding artefacts and structural changes in the samples caused by human errors. In addition, specimen handling is a laborious and time-consuming task and requires skilful and experienced personnel. This paper introduces a flexible microrobotic platform for the handling of microscale specimens of fibrous materials for various microscopic studies such as scanning electron microscopy and nanotomography. The platform is capable of handling various fibres with diameters ranging from 10 to 1000 µm and lengths of 100 µm-15 mm, and mounting them on different types of specimen holders without damaging them. This tele-operated microrobotic platform minimizes human interaction with the samples, which is one of the main sources contributory to introducing artefacts into the specimens. The platform also grants a higher throughput and an improved success rate of specimen handling, when compared to the manual processes. The operator does not need extensive experience of microscale manipulation and only a short training period is sufficient to operate the platform. The requirement of easy configurability for various samples and sample holders is typical in the research and development of materials in this field. Therefore, one of the main criteria for the design of the microrobotic platform was the ability to adapt the platform to different specimen handling methods required for microscopic studies. To demonstrate this, three experiments are carried out using the microrobotic platform. In the first experiment, individual paper fibres are mounted successfully on scanning electron microscopy specimen holders for the in situ scanning electron microscopy diagonal compression test of paper fibres. The performance of the microrobotic platform is compared with a skilled laboratory worker performing the same experiment. In the second experiment, a strand of human hair and an individual paper fibre bond are mounted on a specimen holder for nanotomography studies. In the third experiment, individual paper fibre bonds with controlled crossing and vertical angles are made using the microrobotic platform. If an industrial application requires less flexibility but a higher speed when handling one type of sample to a specific holder, then the platform can be automated in the future.

Nanotechnology ; 20(39): 395703, 2009 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-19724112


We present here a proof-of-principle study of scanning probe tips defined by planar nanolithography and integrated with AFM probes using nanomanipulation. The so-called 'nanobits' are 2-4 microm long and 120-150 nm thin flakes of Si(3)N(4) or SiO(2), fabricated by electron beam lithography and standard silicon processing. Using a microgripper they were detached from an array and fixed to a standard pyramidal AFM probe or alternatively inserted into a tipless cantilever equipped with a narrow slit. The nanobit-enhanced probes were used for imaging of deep trenches, without visible deformation, wear or dislocation of the tips of the nanobit after several scans. This approach allows an unprecedented freedom in adapting the shape and size of scanning probe tips to the surface topology or to the specific application.

Nanotechnology ; 19(49): 495503, 2008 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-21730675


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.

IEE Proc Nanobiotechnol ; 151(4): 145-50, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16475859


Current research activities on the development of a system for transport and manipulation of biological cells with microrobots are described. If single cells in liquid are to be placed on a grid or sorted by cell type, having a system that can automatically lift, transport and release cells can significantly speed up such a tedious task. Therefore, a system is being developed that can automatically sort different cells by transporting them to different repositories. A method to recognise different types of cells is also being developed. The system consists of several components; a motorised inverted microscope, several different microrobots and a software architecture to control the whole cell manipulation workstation and to provide a user interface.

Ultramicroscopy ; 86(1-2): 181-90, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11215622


Micromanipulation tasks have to be solved in the assembly of microsystems, the handling of biological cells and the handling of specimens for scanning electron microscopy. For these applications, we have developed a flexible micromanipulation station, including direct-driven robots a few cubic centimeters small. The robots are able to perform high-precise manipulation and positioning of microobjects. Force-controlled microgripping strategies are now necessary to develop robust microassembly strategies. Microgripping is different from conventional gripping in two ways. First, microparts with dimensions less than 100 microm are often fragile and can easily be damaged during gripping, thus special grasping techniques are needed. Second, the mechanics of manipulation in the microworld are much different than in the macro-world. Part interactions in the microworld are dominated by adhesive forces making it difficult to release parts during manipulation tasks. Several microgrippers that do not employ force feedback have been developed; force-controlled microgrippers are much less common. Grippers with integrated piezoresistive force sensors and with attached strain gauges have been reported. These approaches, however, are limited in their ability to resolve the gripping force. Hence, we are currently integrating self-sensing SPM cantilevers into a gripper of our microrobots. These cantilevers operate by measuring stress-induced electrical resistance changes in an implanted conductive channel in the flexure legs of the cantilever. The real-time force feedback provided by these sensors enables us to better understand the prevailing nano forces and dynamics, what is indispensable for reliable micromanipulation strategies.