Nanometer resolution TEM sample manipulator for rotational and translational positioning

The design and fabrication process for a high performance manipulation stage for nanometer resolution TEM sample positioning over a 20 μm range is presented. A two level, planar stage is moved in three translational and three rotational directions by just two types of actuators; three horizontal and three vertical combdrives. The vertical combdrives are suspended by optimally designed torsion-beams, improving lateral stiffness by at least a factor of 50 compared to rectangular beams, hence minimizing the chance of electrostatic side pull-in

The Twente humanoid head

This video shows the results of the project on the mechatronic development of the Twente humanoid head. The mechanical structure consists of a neck with four degrees of freedom (DOFs) and two eyes (a stereo pair system) which tilt on a common axis and rotate sideways freely providing a three more DOFs. The motion control algorithm is designed to receive, as an input, the output of a biological-inspired vision processing algorithm and to exploit the redundancy of the joints for the realization of the movements. The expressions of the humanoid head are implemented by projecting light from the internal part of the translucent plastic cover

Performance optimization of large stroke flexure hinges for high stiffness and eigenfrequency

Two flexure hinge types are optimized for high support stiffness and high first unwanted eigenfrequency for two different working ranges, ±5.7° and ±20°. We show how multiple performance specifications lead to different designs with different performance. The optimization uses efficient parameterized non-linear beam-based models. The constraints and load case are taken from an electron microscopy use case. Optimization results show that the Three Flexure Cross Hinge has the highest first unwanted eigenfrequencies, while the new Infinity Flexure Hinge shows highest support stiffnesses. The design of the optimal geometry is detailed such that a prototype mechanism is manufactured and tested. Experiments show that the first unwanted eigenfrequency is 35 times higher than the first eigenfrequency throughout the working range

Single-mask thermal displacement sensor in MEMS

In this work we describe a one degree-of-freedom microelectromechanical thermal\ud displacement sensor integrated with an actuated stage. The system was fabricated in the device layer of a silicon-on-insulator wafer using a single-mask process. The sensor is based on the temperature dependent electrical resistivity of silicon and the heat transfer by conduction through a thin layer of air. On a measurement range of 50 μm and using a measurement bandwidth of 30 Hz, the 1-sigma noise corresponds to 3.47 nm. The power consumption of the sensor is 209 mW, almost completely independent of stage position. The drift of the sensor over a measurement period of 32 hours was 32 nm

Design and modeling of a precision 6 DOF MEMS-based parallel kinematic TEM sample manipulator

A design for a 6 Degree-of-freedom precision MEMS-based manipulator for a TEM will is presented. The elastic mechanism is designed and modeled with the specific design considerations regarding kinematic constraint design and elastic energy storage. The typical relatively large deformations of elastic hinges in MEMS result in relatively large displacements and large rigid body rotations. For accurate analysis geometrically non-linear elasticity theory has been used. The drive stiffness has great influence on the longitudinal stiffness of leaf-springs. Leaf-springs used at a relatively low drive stiffness, as is usually the case in MEMS, can benefit from reinforcement, but only in certain cases. The stiffness and so the natural frequency decrease due to deflection of elastic elements in a system can be drastic. In the proposed hexapod design the maximum lowest natural frequency shift due to a displacement of 25 μm is only 10