Microsurface scale characteristics (roughness, waviness and form) and the workpiece mounting fixture effects must be accounted and compensated for during laser micromachining such that the focused laser spot position is known in the coordinates of the measured surfaces. Thus, allowing rapid and accurate micromachining on the true workpiece engineering surface. The thin-plate splines (TPSs), a mathematically simple theory, is modified and employed in the reconstruction of 2 1/2 D unfolded continuous and differentiable microtopographical surfaces from a limited set of sampled digital elevation data. The TPS theory aids in restoring bad samples and in enhancing the visualization of the reconstructed surface and the characterization of microelectromechanical systems (MEMS) structures. The reverse engineered surface could also be interfaced and used with a CAD/CAM system to compensate for the focal spot location of a laser beam based on the actual reversed engineered workpiece surface. The practical examples of the real microsurfaces presented in this work, combine comprehensive identification with the ultimate goal of utilizing the algorithms in the compensation of the laser focused spot for a femtosecond laser micromachining (FLM) system currently under development in our laboratory.

Microgrippers based on electrothermal actuation were designed and fabricated using the deep reactive ion etching (DRIE) process with 100mum thick silicon on insulator (SOI) wafer. The design requirements are restricted to basic manipulation tasks such as pick and place, and nonprehensile manipulation. This paper explores several electrothermal end-effectors which have been fabricated for serial and parallel microassembly. The end-effectors include three main building blocks: 1) Integrated and symmetrical actuators of V and U shapes. The symmetrical expansions on Chevron and hot arms allow combination of forward translations that amplify angular motion at the tips of a gripper. 2) A joule heating element based on a resistive V-shape electrothermal actuator. In 3D microassembly, the joining of a micropart is essentially performed by providing an integrated microheater device. 3) A force or position feedback sensing block based on self-straining or electrostatic principle. The integrated sensor can be calibrated for both position and force measurements. Serial heterogeneous assembly of meso and micro-scale objects is demonstrated using a 3D microassembly station. Black-box dynamical models for microgrippers are derived using experimentally obtained data, and performance variations due to the way the microgrippers are mounted onto the robot are discussed.