This paper presents the design, fabrication and testing of a fiber optic switch actuated electromagnetically. The
ferromagnetic gel coated optical fiber is actuated using external electromagnetic fields. The ferromagnetic gel consists of
ferromagnetic powders dispersed in epoxy. The fabrication utilizes a simple cost-effective coating setup. A direct
fiberto-fiber alignment eliminates the need for complementary optical parts and the displacement of fiber switches the laser
coupling. The magnetic characteristics of magnetized ferromagnetic materials are performed using alternating gradient
magnetometer and the magnetic hysteresis curves are measured for different ferromagnetic materials including iron,
cobalt, and nickel. Optical fiber switches with various fiber lengths are actuated and their static and dynamic responses
for the same volume of ferromagnetic gel are summarized. The highest displacement is 1.345 mm with an input current
of 260mA. In this paper, the performance of fiber switches with various coating materials is presented.
This paper discusses modeling, design, fabrication and characterization of an optical scanner based on cantilever-type
electrostatic zipping actuators. The electrostatic actuator has been designed to achieve high displacements for large
optical scanning angles at lower actuation voltages. The zipping actuators are fabricated using multi-layer polysilicon
foundry fabrication processes. The electrostatic force between the cantilever and the bottom electrode on the substrate
pulls the cantilever down. With a warped cantilever, the force closes the gap from the anchored end and gradually the
zipping effect actuates the entire cantilever. In our design, mechanical structures are arranged to avoid electrical shortcircuit.
With various annealing temperatures, the warped angles are controllable. The cantilever serves as a reflective
surface and the high out-of-plane displacement is used to steer a reflected laser beam for imaging and scanning
applications. In this paper we present the design considerations in electrostatic zipping actuator displacement and
control as well as the arrangement for optical scanning.
A compact fiber optic scanner for biomedical applications such as optical coherent tomography has been designed,
fabricated and tested. The scanner is designed as an in vivo device and composed of an optical fiber coated with nickel-powder
loaded paint for external magnetic actuation. The compactness of the imaging device makes it suitable for
applications where size, precision and low power consumption is critical. We have previously demonstrated the
principles utilizing magnetic actuation for the fiber scanner coated with magnetic gel. This work focused on verification
and optimization of the scanner operation. The magnetic properties of the nickel particle mixed with paint were
characterized using an alternating gradient magnetometer. The optical scanner is externally actuated by an
electromagnet and so it does not require a voltage or current supply in the probe itself. The displacements of the scanner
were recorded using a position sensitive detector. The result showed a 0.8-mm displacement under the influence of a
static magnetic field of 17.6 KA/m in a fiber with a moveable length of 4.2cm. Dynamic analysis showed a
displacement of 0.83mm with an input current amplitude of 41mA and a magnetic field of 2.4 KA/m. The
measurements are in good agreement with the theoretical lumped-element calculations. Finite-element analysis was
performed and the results agree with the theoretical and experimental results. The static and dynamic displacements of
the fiber optic scanner depend on the thickness and length of the magnetic coating. Thus, scanners for different
displacements and operating frequencies can be designed by varying the coating thickness and length.
In this paper, we present design, modeling, fabrication, testing techniques and experimental verification for a bi-directional
thermal actuator. The actuation principle is based on the asymmetrical thermal expansion of pseudo-bimorph
microstructures due to the difference in the electrical resistance of two stacked poly-silicon layers. Bi-directional
actuation is achieved depending upon the application of currents on either the top or bottom layers. Various designs
were fabricated using the commercial foundry process PolyMUMPS and characterized with a reflective microscope and
an optical profiler. Previous demonstrated designs had a limited vertical displacement due to the mechanical limitation
imposed by the flexural lengths of the actuator arms. We proposed a new design allowing an increase of the maximum
displacement by 85% with the same input voltage of 7V. The flexure arm is incorporated in the top silicon layer such
that the torsion forces on the flexural arms are minimized. This enables larger deflection of the actuator arm without
significant increase in the temperature. Different device configurations have been designed and tested. The temperature
distributions on the actuator arms and displacements of the actuators at various conditions were analyzed using finite-element
analysis and verified experimentally. We will discuss the design configuration, testing techniques and practical
issues. The potential applications of the out-of-plane actuators include flow sensors, variable capacitors, resistive
sensors, optical switches and RF switches.
This paper discussed modeling, design, fabrication and characterization of a new cantilever-type electrostatic zipping
actuator. The actuator was designed to achieve high displacements and fabricated using multi-layer polysilicon foundry
fabrication process PolyMUMPS. The high out-of-plane displacement is to satisfy the requirements in specific optical
applications. In this paper we presented the design considerations in displacement, electrostatic forces and electrostatic
stability. The electrostatic force between the curved cantilever and the bottom electrode on the substrate pulls the
cantilever down. With a warped cantilever, the force closes the gap from the anchor end and gradually the zipping effect
actuates the entire cantilever without increasing the biasing voltages. Previous electrostatic zipper actuators require a
thin layer of dielectric material on top of the bottom electrode to prevent electrical shorting. They may have an issue
with electrical breakdown of the thin dielectric layer due to the film quality. We designed a new mechanical structure to
avoid the electrical shorting problem without a layer of dielectric material. Our analysis and experimental results
demonstrated that the proposed design can withstand high voltages without shorting and is capable of high deflection.
The vertical displacements of different device configurations were found ranging from 30.4μm to 450μm while the
actuation voltages varied in the range from 12V to 45.3V for complete actuation. The pull-in voltages for various
configurations were analyzed and presented.
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