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This paper covers the design, fabrication, and characterization of two-layer microcoils wherein an unannealed plasma-enhanced CVD Si[O.sub.2] functions as the insulator between silicon-and photoresist-molded copper coils. This design overcomes the thermal limitations placed upon coils that are embedded within polymer molds and thereby enables higher current carrying capability. The fabrication process is compatible with deep reactive-ion etching and may be used to integrate coils with flexures/compliant mechanisms. Thermal and mechanical limitations were determined experimentally and used to create design rules that limit the coil design space. The breakdown strength of the unannealed Si[O.sub.2] was measured at 4.6 MV/cm. Experiments show that coils with 40-[micro]m pitch, 30 x 30-[micro][m.sup.2] winding cross section, and Si[O.sub.2] thickness of 1 [micro]m may carry more than 1 A (larger than [10.sup.9] A/[m.sup.2]) with less than 10[degrees]C temperature change. These characteristics make the coils useful in small-scale actuators and power systems. [2008-0170] Index Terms--Copper damascene, electroplating, magnetic microactuator, microcoil, microelectromechanical devices, silicon dioxide.

In this paper, we disclose how to contour the beams of microscale thermomechanical actuators (TMAs) in order to enhance the actuator's thermal and mechanical performance. In this approach, we vary the cross-section of the heated beams over the length of the beams. Using this approach, the stored strain energy and axial stiffness of the beam may be modified to achieve an optimized force-displacement relationship. Examples are provided to show that in some designs: 1) the maximum achievable thermal strain of a driving beam may be increased by 29%, 2) actuator stroke may be increased by a factor of four, and 3) identical force or displacement characteristics may be achieved with a 90% reduction in power. This paper presents the theory and models used to predict the thermal and mechanical behavior of the actuator. The theory and models were used to create a deterministic link between the actuator's design parameters and the actuator's performance characteristics. The theory and models were combined within a design tool that is posted at http://pcsl.mit.edu. The tool has been used to generate performance plots that enable designers to: 1) understand the quantitative relationships between design parameters and performance and 2) rapidly converge upon first-pass design parameters. [1695] Index Terms--Contoured beam, microactuator, nanopositioner, thermomechanical actuator.

This paper presents the design and characterization of a three-axis thermomechanical actuator-based endoscopic scanner for obtaining ex vivo two-photon images. The scanner consisted of two sub-systems: 1) an optical system (prism, gradient index lens, and optical fiber) that was used to deliver and collect light during imaging and 2) a small-scale silicon electromechanical scanner that could raster scan the focal point of the optics through a specimen. The scanner can be housed within a 7 mm Ø endoscope port and can scan at the speed of 3 kHz x 100 Hz × 30 Hz along three axes throughout a 125 × 125 × 100 μm3 volume. The high-speed thermomechanical actuation was achieved through the use of geometric contouring, pulsing technique, and mechanical frequency multiplication (MFM), where MFM is a new method for increasing the device cycling speed by pairing actuators of unequal forward and returning stroke speeds. Sample cross-sectional images of 15-μm fluorescent beads are presented to demonstrate the resolution and optical cross-sectioning capability of the two-photon imaging system. [ABSTRACT FROM AUTHOR]

In this paper, we disclose how to contour the beams of microscale thermomechanical actuators (TMAs) in order to enhance the actuator's thermal and mechanical performance. In this approach, we vary the cross-section of the heated beams over the length of the beams. Using this approach, the stored strain energy and axial stiffness of the beam may be modified to achieve an optimized force-displacement relationship. Examples are provided to show that in some designs: 1) the maximum achievable thermal strain of a driving beam may be increased by 29%, 2) actuator stroke may be increased by a factor of four, and 3) identical force or displacement characteristics may be achieved with a 90% reduction in power. This paper presents the theory and models used to predict the thermal and mechanical behavior of the actuator. The theory and models were used to create a deterministic link between the actuator's design parameters and the actuator's performance characteristics. The theory and models were combined within a design tool that is posted at http://pcsl.mit.edu. The tool has been used to generate performance plots that enable designers to: 1) understand the quantitative relationships between design parameters and performance and 2) rapidly converge upon first-pass design parameters. [ABSTRACT FROM AUTHOR]