Multi-Photon Vertical Cross-Sectional Imaging With a Dynamically-Balanced Thin-Film PZT z-Axis Microactuator

Choi, Jongsoo; Duan, Xiyu; Li, Haijun; Wang, Thomas D.; Oldham, Kenn R.

doi:10.1109/jmems.2017.2701798

Cited by 5 publications

(2 citation statements)

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“…Relating nonlinearities to structural behavior at large displacements, this paper analyzes how the stiffness of the scanner changes in multiple directions due to fabrication-related non-idealities as its position changes and then examines its effect on the resonant frequencies. Building on the authors’ previous work [9] that analyzed static behavior or linear dynamics about a single operating point [12], the stiffness of the legs of the micro-scanner are modeled in multiple axes to capture coupled motion in different directions. The non-idealities taken into consideration in the presented model include non-uniform residual stress on the beams and an asymmetrically perturbed stage.…”

Section: Introductionmentioning

confidence: 99%

“…Due to its symmetric design, these scanners are sensitive to non-ideal fabrication outcomes that cannot be perfectly eliminated, such as dimensional variation and non-uniform residual stress. This problem can be solved by using a differential drive [9] with feedback control, or limiting actuation to individual frequencies where a combination of different modes produces a desired motion, such as pure vertical motion [12]. Resonant mode operation in one or more axes is often advantageous because large displacement can be obtained at even lower voltage, but the coupling of different vibration modes and shift of natural frequencies as static deflections and operating conditions change need to be characterized and understood.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of thin-film piezoelectric microactuators with large vertical stroke subject to multi-axis coupling and fabrication asymmetries

Choi

Wang

Oldham

2017

J. Micromech. Microeng.

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The high performance and small size of MEMS based scanners has allowed various optical imaging techniques to be realized in a small form factor. Many such devices are resonant scanners, and thus their linear and nonlinear dynamic behaviors have been studied in the past. Thin-film piezoelectric materials, in contrast, provide sufficient energy density to achieve both large static displacements and high-frequency resonance, but large deformation can in turn influence dynamic scanner behavior. This paper reports on the influence of very large stroke translation of a piezoelectric vertical actuator on its resonant behavior, which may not be otherwise explained fully by common causes of resonance shift such as beam stiffening or nonlinear forcing. To examine the change of structural compliance over the course of scanner motion, a model has been developed that includes internal forces from residual stress and the resultant additional multi-axis coupling among actuator leg structures. Like some preceding vertical scanning micro-actuators, the scanner of this work has four legs, with each leg featuring four serially connected thin-film PZT unimorphs that allow the scanner to generate larger than 400μm of vertical displacement at 14V. Using an excitation near one or more resonances, the input voltage can be lowered, and complementary multi-axis rotations can be also generated, but change of the resonant frequencies with scanner height needs to be understood to maximize scanner performance. The presented model well predicts the experimental observation of the decrease of the resonant frequencies of the scanner with the increase of a dc bias voltage. Also, the effects of the magnitude and uniformity of residual stress across the scanner structure on the natural frequencies have been studied.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%