Design,modeling and test of a novel compliant orthogonal displacement amplification mechanism for the compact micro-grasping system

In the compact micro-grasping system, the combination of precisely orthogonal movement transformation, displacement amplification and simple structure is important. The typical solution of the combination issue requires bidirectional symmetric input forces/displacements. However, under a certain driving condition, numerous actuators used in micro-manipulation only supply unidirectional input froce/displacement for the driven mechanism, which makes the typical solution infeasible. In this study, a novel compliant orthogonal displacement amplification mechanism (DAM) is proposed to solve the combination issue for numerous actuators used in micro-grasping. The proposed mechanism is a triangulation amplification-based mechanism with undetermined structural parameters. The number of the undetermined parameters and the solution principle are analyzed. The design process is presented. Finite element analysis (FEA) is used to verify the design method. The FEA results show that, for the design examples, the errors evaluating the orthogonal movement transformation are smaller than 0.56 % and 0.15 % respectively, and the displacement amplification ratios are larger than 4.6. The orthogonal displacement amplification is realized. A precise model of the displacement amplification ratio is derived. The dynamic performances of the proposed orthogonal DAM are modeled and FEA verified. Furthermore, a microgripper utilizing the proposed mechanism is presented. The performances of the gripper, including the displacement amplification and the parallel movement of the jaws, are verified by FEA and experiments.

     

Resist-free processing of graphene merging optical imaging and classification with scanning probe lithography

Resist based lithographical techniques are widely applied for graphene processing. These resists can leave residues leading to parasitic effects that deteriorate the desired properties of graphene. This paper presents an experimental setup tailored for resist-free robotic processing of graphene with in-situ vision based control. A robust graphene detection and classification approach is presented applying multiple image processing operations of the visual feedback provided by a high-resolution light microscope. Detected graphene flakes can be modified using scanning probe based lithographical processes, such as mechanical and bias-assisted approaches, that are directly linked to the in-situ optical images. The results of this process are discussed with respect to further application scenarios.     

MRI-based dynamic tracking of an untethered ferromagnetic microcapsule navigating in liquid

The propulsion of ferromagnetic objects by means of MRI gradients is a promising approach to enable new forms of therapy. In this work, necessary techniques are presented to make this approach work. This includes path planning algorithms working on MRI data, ferromagnetic artifact imaging and a tracking algorithm which delivers position feedback for the ferromagnetic objects, and a propulsion sequence to enable interleaved magnetic propulsion and imaging. Using a dedicated software environment, integrating path-planning methods and real-time tracking, a clinical MRI system is adapted to provide this new functionality for controlled interventional targeted therapeutic applications. Through MRI–based sensing analysis, this article aims to propose a framework to plan a robust pathway to enhance the navigation ability to reach deep locations in the human body. The proposed approaches are validated with different experiments.     

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.     

Design of single-axis flexure hinges using continuum topology optimization method

The design of compliant hinges has been extensively studied in the size and shape level in the literature.This paper presents a method for designing the single-axis flexure hinges in the topology level.Two kinds of hinges,that is,the translational hinge and the revolute hinge,are studied.The basic optimization models are developed for topology optimization of the translational hinge and the revolute hinge,respectively.The objective for topology optimization of flexure hinges is to maximize the compliance in the desired direction meanwhile minimizing the compliances in the other directions.The constraints for accomplishing the translational and revolute requirements are developed.The popular Solid Isotropic Material with Penalization method is used to find the optimal flexure hinge topology within a given design domain.Numerical results are performed to illustrate the validity of the proposed method.     

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.     

Autonomous Microrobots

Robots have been a subject of research for almost half a century. In order to make robots more versatile they must be able to operate in a semi-structured work place where unforeseen events occur and where sensor data are incomplete. An entire research community has been working on this problem and many unique autonomous and so-called intelligent robots have been conceived and built. Most of these efforts are concerned with robots that operate in the macroworld where they take on chores that could also be handled by humans. However, there is the mocroworld in which manipulation and handling tasks are very difficult and for which a human has no tools and where the work area is so small that fine manual manipulation is almost impossible. This paper is concerned with autonomous robots that can operate in a microworld, where microassembly operations, microsurgery or integrated circuit testing and repair is done. For independent operations, these robots need special sensors and an efficient computer architecture that hosts the planner and executor. There are also special drive systems and effectors necessary for micromotions and micromanipulations, respectively. An attempt is made to describe these components and the problems encountered in configuring them to a microrobot. As an example of advanced microrobots, the design and functions of several autonomous microrobots of the University of Karlsruhe are shown; they employ different locomotion and subject handling principles. The paper also includes a discussion of the typical operating problems caused by the microworld and of future research that has to be done to conceive and build efficient microrobots.