Laser scanners have been an integral part of MEMS research for more than three decades. During the last decade, miniaturized projection displays and various medicalimaging applications became the main driver for progress in MEMS laser scanners. Portable and truly miniaturized projectors became possible with the availability of red, green, and blue diode lasers during the past few years. Inherent traits of the laser scanning technology, such as the very large color gamut, scalability to higher resolutions within the same footprint, and capability of producing an always-in-focus image render it a very viable competitor in mobile projection. Here, we review the requirements on MEMS laser scanners for the demanding display applications, performance levels of the best scanners in the published literature, and the advantages and disadvantages of electrostatic, electromagnetic, piezoelectric, and mechanically coupled actuation principles. Resonant high-frequency scanners, low-frequency linear scanners, and 2-D scanners are included in this review. [2013-0235]

Abstract-A resonant piezoelectric scanner is developed for high-resolution laser-scanning displays. A novel actuation scheme combines the principle of mechanical amplification with lead zirconate titanate (PZT) thin-film actuation. Sinusoidal actuation with 24 V at the mechanical resonance frequency of 40 kHz provides an optical scan angle of 38.5• for the 1.4-mm-wide mirror. This scanner is a significant step toward achieving full-highdefinition resolution (1920 × 1080 pixels) in mobile laser projectors without the use of vacuum packaging. The reported piezoscanner requires no bulky components and consumes < 30-mW power at maximum deflection, thus providing significant power and size advantages, compared with reported electromagnetic and electrostatic scanners. Interferometry measurements show that the dynamic deformation is at acceptable levels for a large fraction of the mirror and can be improved further for diffraction-limited performance at full resolution. A design variation with a segmented electrode pair illustrated that reliable angle sensing can be achieved with PZT for closed-loop control of the scanner.[ 2012-0116]Index Terms-High-frequency laser beam scanning, lead zirconate titanate (PZT) thin-film-actuated, microelectromechanical systems (MEMS), MEMS mirror, resonant scanner.

A comb-actuated torsional microscanner is developed for high-resolution laser-scanning display systems. Typical torsional comb-drive scanners have fingers placed around the perimeter of the scanning mirror. In contrast, the structure in this paper uses cascaded frames, where the comb fingers are placed on an outer drive frame, and the motion is transferred to the inner mirror frame with a mechanical gain. The structure works only in resonant mode without requiring any offset in the comb fingers, keeping the silicon-on-insulator-based process quite simple. The design intent is to improve actuator efficiency by removing the high-drag fingers from the high-velocity scanning mirror. Placing them on the lower velocity drive frame reduces their contribution to the damping torque. Furthermore, placement on the drive frame allows an increase of the number of fingers and their capacity to impart torque. The microscanner exhibits a parametric response, and as such, the maximum deflection is found when actuated at twice its natural frequency. Analytical formulas are given for the coupled-mode equations and frame deflections. A simple formula is derived for the mechanical-gain factor. For a 1-mm × 1.5-mm oblong scanning mirror, a 76 • total optical scan angle is achieved at 21.8 kHz with 196-V peak-to-peak excitation voltages.[2009-0304]

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Aligned and stretched lambda DNA is directed to specific locations on solid substrates. Surface-energy modification of glass substrates by using patterned polydimethylsiloxane (PDMS) stamps is used to direct DNA onto the surface-energy-modified micrometer-scale pattern through molecular combing. As an alternative, patterned and nonpatterned PDMS stamps modified with polymethylmethacrylate (PMMA) are utilized to direct the stretched DNA to the desired location and the results are compared. The DNA is elongated through molecular combing on the stamp and transfer printed onto the surfaces. PMMA-modified stamps show a more defined length of the stretched DNA, as compared to bare PDMS stamps. A combination of these two methods is also demonstrated. As an application example, transfer printing of DNA decorated with a semiconducting conjugated polyelectrolyte is shown. The resulting patterned localization of stretched DNA can be utilized for functional nanodevice structures, as well as for biological applications.