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|Title: ||BULK-PIEZOELECTRIC TRANSDUCTION OF MICROSYSTEMS WITH APPLICATIONS TO BATCH-ASSEMBLY OF MICROMIRRORS, CAPACITIVE SENSING, AND SOLAR ENERGY CONCENTRATION|
|Authors: ||Ardanuç, Serhan Mehmet|
|Keywords: ||Bulk-PZT actuation|
Concentrating solar power
|Issue Date: ||May-2010|
|Abstract: ||Electromechanical modeling, actuation, sensing and fabrication aspects of bulkpiezoelectric
ceramic integration for microsystems are investigated in this thesis.
A small-signal model that describes the energy exchange between surface micromachined
beams and bulk-lead zirconium titanate (PZT) actuators attached to
the silicon substrate is presented. The model includes detection of acoustic waves
launched from electrostatically actuated structures on the surface of the die, as
well as their actuation by bulk waves generated by piezoelectric ceramics. The
interaction is modeled via an empirical equivalent circuit, which is substantiated
by experiments designed to extract the model parameters.
As a die level application of bulk-PZT, an Ultrasound Enhanced Electrostatic
Batch Assembly (U2EBA) method for realization of 3-D microsystems is demonstrated.
U2EBA involves placing the die in an external DC electric field perpendicular
to the substrate and actuating the die with an off-chip, bulk-piezoelectric
ceramic. Yield rates reaching up to 100% are reported from 8×8 arrays of hinged
mirrors with dimensions of 180 × 100 micrometre-squared.
U2EBA is later improved to provide temporary latching at intermediate angles
between fully horizontal and vertical states, by using novel latching structures. It
is shown that the micromirrors can be trapped and freed from different rotation
angles such that zero static power is needed to maintain an angular position.
The zero-idle-power positioning of large arrays of small mirrors is later investigated
for energy redirection and focusing. All-angle LAtchable Reflector (ALAR)
concept is introduced, and its application to Concentrated Solar Power (CSP)
systems is discussed. The main premise of ALAR technology is to replace bulky
and large arrays of mirrors conventionally used in CSP technologies with zeroidle-
power, semi-permanently latched, low-profile, high-fill factor, micrometer to
centimeter scale mirror arrays. A wirelessly controlled prototype that can move a
2-D array of mirrors, each having a side length of less than 5 cm, in two degrees
of freedom to track the brightest spot in the ambient is demonstrated.
Capacitive sensing using bulk-piezoelectric crystals is investigated, and a Time-
Multiplexed Crystal based Capacitive Sensing (TM-XCS) method is proposed to
provide nonlinearity compensation and self-temperature sensing for oscillator based
capacitive sensors. The analytical derivation of the algorithm and experimental
evidence regarding the validity of some of the relations used in the derivation are
This thesis also presents results on microfluidic particle transport as another
application of bulk-PZT in microsystems. Experiments and work regarding actuation
of micro-scale, fluorescent beads on silicon nitride membranes are described.|
|Appears in Collections:||Theses and Dissertations (OPEN)|
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