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BEGIN:VEVENT
DTSTAMP:20261020T043609Z
LAST-MODIFIED:20180706T142048Z
DTSTART:20180731T170000Z
DTEND:20180731T180000Z
UID:event1954@bu.edu
URL:http://physics.bu.edu/internal/events/show/1954
SUMMARY:Nonlinear Mechanics and Nonlinear Material Properties in Micromecha
	nical Resonators
DESCRIPTION:Featuring Joseph Boales\n\nPart of the PhD Final Oral Exams.\n\
	nDissertation Committee:  Raj Mohanty\, Alex Sushkov\, Claudio Chamon\, Rob
	ert Carey\, Shyam Erramilli\n\nAbstract:\n\nMicroelectromechanical Systems 
	are ubiquitous in modern technology\, with applications ranging from accele
	rometers in smartphones to ultra-high precision motion stages used for atom
	ically-precise positioning. With the appropriate selection of materials and
	 device design\, MEMS resonators with ultra-high quality factors can be fab
	ricated at minimal cost. As the sizes of such resonators decrease\, however
	\, their mechanical\, electrical\, and material properties can no longer be
	 treated as linear\, as can be done for larger-scale devices. Unfortunately
	\, adding nonlinear effects to a system changes its dynamics from exactly-s
	olvable to only solvable in specific cases\, if at all. Despite (and becaus
	e of) these added complications\, nonlinear effects open up an entirely new
	 world of behaviors that can be measured or taken advantage of to create ev
	en more advanced technologies.\n\nIn our resonators\, oscillations are indu
	ced and measured using separate aluminum nitride transducers. I used this m
	echanism for several separate highly-sensitive experiments. In the first\, 
	I demonstrate the incredible sensitivity of these resonators by actuating a
	 mechanical resonant mode using only the force generated by the radiation p
	ressure of a laser at room temperature. \n\nIn following three experiments\
	, which use similar mechanisms\, I demonstrate information transfer and for
	ce measurements by taking advantage of the nonlinear behavior of the resona
	tors. When nonlinear resonators are strongly driven\, they exhibit sum and 
	difference frequency generation\, in which a large carrier signal can be mi
	xed with a much smaller modulation to produce signals at sum and difference
	 frequencies of the two signals. These sum and difference signals are used 
	to detect information encoded in the modulation signal using optical radiat
	ion pressure\, electromagnetic heating\, and acoustic pressure waves.\n\nFi
	nally\, in my experiments\, I probe the nonlinear nature of the piezoelectr
	ic material rather than take advantage of the nonlinear resonator behavior.
	 The relative sizes of the linear and nonlinear portions of the piezoelectr
	ic constant can be determined because the force applied to the resonator by
	 a transducer is independent of the dielectric constant. This method allowe
	d me to quantify the nonlinear constants.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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