This paper presents the fabrication of a three-dimensional microcoil through the technique of microassembly. The microcoil design is comprised of nine out-of-plane micro-sized windings. Each winding was assembled onto the base substrate orthogonally by a robotic manipulator through microassembly. In contrast to the conventional serial pick-and-place microassembly, this work incorporated the approach of parallel microassembly to grasp and assemble three windings onto the base substrate simultaneously for increased productivity. In addition, a vision-based algorithm was developed to automate the parallel grasping process of three windings. This algorithm utilized well-defined templates to provide high-precision position and orientation evaluations for the micro-sized components. The performance of the microcoil fabrication process was evaluated and discussed. To establish better electrical contact between the windings and the base substrate, conductive adhesive was introduced in the assembly process and the electrical properties of the assembled microcoil structure were examined.

We present a fully automated micrograsping methodology that uses a micro-robot and a microgripper to automatically grasp a micropart in three-dimensional (3-D) space. To accurately grasp a micropart in 3-D space, we propose a three-stage micrograsping strategy: (i) coarse alignment of a micropart with a microgripper in the image plane of a video camera system; (ii) alignment of the micropart with the microgripper in the direction normal to the image plane; (iii) fine alignment of the micropart with the microgripper in the image plane, until the micropart is completely grasped. Two different vision-based feedback controllers are employed to perform the coarse and fine alignment in the image plane. The vision-based feedback controller used for the fine alignment employs position feedback signals obtained from two special patterns, which can achieve submicron alignment accuracy. Fully automated micrograsping experiments are conducted on a microassembly robot. The experimental results show that the average alignment accuracy achieved during automated grasping is approximately ± 0.07 μm; the time to complete an automated micrograsping task is as short as 7.9 seconds; and the success rate is as high as 94%.

This paper describes a new visual force sensing method for measuring microforces acting upon the jaws of passive microgrippers used in the assembly of MEMS devices. The importance of force measurement during microassembly is to confirm the microgripper-micropart make a successful grasp and to also protect the microparts and microgripper from excessive forces which may lead to damage during the assembly process. In the proposed approach, the force measurement problem is reduced to a problem of determining the microgripper jaw displacement. A 3-D finite element model is developed to study the relation between the forces and the displacements. The resulting nonlinear force-displacement relationship is fitted into a second degree equation. Computer vision is used to measure the relative displacements of the right and left microgripper jaws with respect to the microgripper base during assembly. Patterns that were introduced to the microgripper during the design phase are used to measure those relative displacements through pattern identification. Two-dimensional pattern identification is performed using normalized cross correlation template matching, to estimate the degree to which the image and pattern are correlated

This paper describes the design and development of a 6 degree of freedom robotic manipulator used in the assembly of three-dimensional MEMS (micro electromechanical systems) microstructures. The robot employs a highly innovative mechanical design for the rotational axes to provide unprecedented access to a microchip substrate for microassembly operations. The first three axes of the robotic manipulator are orthogonally mounted linear stages providing Cartesian positioning of the chips beneath the end effector (microgripper). A rotational stage (alpha) mounted on the distal end of these three Cartesian axes allows the MEMS chip to be rotated. Two more degrees of freedom (beta and gamma) are serially mounted to the base frame, allowing for two degrees of rotation of the end effector. This configuration permits assembly of micro-parts on the surface of a MEMS chip at any orientation angle to the surface, within the limits of the workspace of the manipulator and the resolution of the motors. The end effector employs a standard tungsten probe with a passive microgripper bonded to it, which is used for grasping micro-parts. A software system has been developed to allow automatic operation of the manipulator. Preliminary assembly tests confirm the usefulness of the proposed design

This paper describes the process of bonding a MEMS (Micro-ElectroMechanical System) microgripper to the distal end of a robotic manipulator arm using a molten solder bonding technique. This task is part of ongoing work which involves the development of a general microassembly workstation. The goal of this workstation is to construct 3-D microstructures from MEMS sub-components. The microgrippers bonded using the method described here are 1.5 mm by 0.6 mm in size. The methodology behind the solder bonding approach is presented, along with the design of a custom soldering device referred to as the contact head. The contact head is used as the interface between the robotic manipulator and the microgripper. Experimental results are given in a qualitative discussion. An explanation of the bonding procedure using automated calibration is described, along with pictures from the associated microscopy system, and some scanning electron microscope images.