This paper describes the development of a miniature assembly cell for microsystems. The cell utilizes a transparent electrostatic gripper allowing the use of computer vision for part alignment with respect to the gripper. Part to assembly alignment is achieved via optical triangulation using a fiber-coupled laser and a position sensitive detector (PSD). The system layout, principle of operation and design are described along with the visual and optical control algorithms and their implementation. Experimental measurements of the performance of the stage indicate normal and tangential gripping forces in the range of 0.03-2.5 mN and 1.-9. mN respectively. The visual search algorithm limits the feature tracking speed to 111ms /search. The alignment accuracy of the visual and optical proportional position feedback controls were determined to be ±7 μm and ±10 μm respectively.
Tactile perception of complex symbols through tactile stimulation is an exciting application of a phenomenon known as tactile illusion (TI). Sensation of motion on the skin can be produced by a limited number of discrete mechanical actuators applying light pressure over the skin. This phenomenon can thus be used as a neurophysiological testing tool to determine central and peripheral nervous system injury as well as providing an additional human-machine communication channel. This paper describes the development of a 4 x 5 actuator array of individual vibrating pixels for fingertip tactile communication. The array is approximately one square centimeter and utilizes novel micro-clutch MEMS technology. The individual pixels are turned ON and OFF by pairs of microscopic composite thermal actuators, while the main vibration is generated by a vibrating piezo-electric plate. The physiological parameters required for inducing tactile illusion are described. The fabrication sequence for the thermal micro-actuators along with actuation results are also presented.
A composite actuator based on a polymer electrolyte and metal electrodes is described. Electrode deposition is described qualitatively with corresponding experimental results. A general continuum model describing the transport and deformation of solid polymer electrolyte processes is developed. The formulation is based on global integral postulates for the conservation of mass, momentum, energy, charge, and the second law of thermodynamics. The global equations are then localized in the volume and on the material surfaces bounding the polymer. The model is simplified to a three component system of a fixed negatively charged polymeric matrix, diffusing hydroxonium ions, and free water within the polymer matrix. Contrary to the existing electrostatic models, the deformation is attributed to water induced swelling. The proposed internal pressure based model includes the stress relaxation phenomenon due to water redistribution governed by Darcy's law.
Production of complex Micro-Opto Electro-Mechanical Systems (MOEMS) often requires assembly of a system from individual components built by mutually incompatible processes. This fabrication step also constitutes the largest portion of the total cost (about 80%), and is one of the major roadblocks to successfully implementing a complex microsystem. Our previous experience with such systems shows, that gripping and manipulation of microparts significantly differs from the assembly of macroscopic devices. The main difference stems from the increased role of the surface electrostatic forces and the reduced influence of body forces such as gravity. This paper describes one possible use of the surface forces in the development of a novel optically transparent electrostatic microgripper. The principle of operation, design and simulation of the new device are described. Several models describing the gripping force are also presented. The out-of-plane and in-plane holding (frictional) forces are measured as a function of the applied voltage for two common materials - silicon and nickel. The fabrication sequence and the materials used are discussed.
An anodic bond is modeled as a moving nonmaterial line forming the intersection of three material surfaces representing the unbonded conductor, the unbonded insulator, and the bonded interface. The component mass balance equations, Gauss' law, and the linear momentum equations are placed in a finite element formulation, which is used to predict the evolution of the sodium ion concentration, electric potential, and stress during anodic bonding of Pyrex glass and silicon.
A continuum mechanical model of Nafion based metal-polymer actuators is presented. Global integral postulates are written for the conservation of mass, momentum, energy, and charge, Gauss' law, and the second law of thermodynamics. The global equations are then localized in the volume and on the material surfaces bounding the polymer. A finite element formulation is used to predict the evolution of the counter ion concentration, 'free' water content, electric potential, and stress/strain during actuation. The model includes stress relaxation phenomena due to water flow generated governed by Darcy's law.
The rapid development of reproductive biology has created a need for quantifying penetration forces during artificial fertilization. It has been demonstrated that the success of such procedures heavily depends on the mechanics of penetration of the egg's zona and membrane. To quantify the forces during intracytoplasmic injections we have developed a MEMS based force sensor. Deep RIE and fusion bonding are used to fabricate a variable capacitance type sensor. It is designed to measure the penetration force during intracytoplasmic injection of egg cells as well as other applications in the 1 - 500 micrometers N force range. The sensor measures tri-axial forces using a system of flexible beams subjected to bending and torsion. The process is relatively simple and allows for easy modification of the force range. A penetration pipette tip is attached to the sensor body using a low temperature bonding technique. Calibration, sensitivity and initial experimental data is provided.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.