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Multiferroic Micro-Electromechanical...

D'Agati, Michael J.,

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Multiferroic Micro-Electromechanical Systems for Magnetic Sensing and Wireless Power Transfer in Biomedical Applications /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Multiferroic Micro-Electromechanical Systems for Magnetic Sensing and Wireless Power Transfer in Biomedical Applications // Michael J D'Agati.
Author:	D'Agati, Michael J.,
Description:	1 electronic resource (223 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-12, Section: B.
Contained By:	Dissertations Abstracts International85-12B.
Subject:	Electrical engineering. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31294251
ISBN:	9798382835563

Multiferroic Micro-Electromechanical Systems for Magnetic Sensing and Wireless Power Transfer in Biomedical Applications /
D'Agati, Michael J.,

Multiferroic Micro-Electromechanical Systems for Magnetic Sensing and Wireless Power Transfer in Biomedical Applications /Michael J D'Agati. - 1 electronic resource (223 pages)

Source: Dissertations Abstracts International, Volume: 85-12, Section: B.

Multiferroic micro-electromechanical systems (MEMS) enable small, room temperature, low power magnetic sensing and wireless power transfer (WPT) in biomedical applications.This thesis presents the theory, design, microfabrication, and characterization of multiferroic MEMS magnetic sensors and WPT devices. Iron cobalt/silver (Fe50Co50/Ag) magnetostrictive material is coupled to piezoelectric aluminum nitride (AlN) to form a multiferroic sensor. Low frequency biomagnetic signals are upconverted around the length-extensional beam's 7-16 MHz mechanical resonance to provide Q enhancement to the sensitivity. The up conversion exploits a nonlinear phenomenon of magnetostrictive materials with applied mechanical strain. For two devices studied, modulated sensitivities of 58.4 mA/T and 37.7 mA/T were observed along with resolutions of 5.03 nT/√Hz and 2.72 nT/√Hz over a bandwidth larger than the biomagnetic frequency spectrum (0.1Hz to 1kHz). The sensors' sensitivity was limited by Duffing nonlinearity and the relatively low piezoelectric coefficients of AlN.To improve sensitivity, magnetoelectric sensors were fabricated using (Fe0.5Co0.5)0.92Hf0.08 coupled to 28% aluminum scandium nitride (Al0.72Sc0.28N). Increasing sensitivity improved the resolution from 5.03 nT/√Hz to 2.16 nT/√Hz. To delay the onset of thermal Duffing nonlinearity, various anchoring tether lengths were explored in Fe0.5Co0.5/Ag - AlN magnetoelectric sensors to provide better heat conduction away from the structure. Also, silicon dioxide (SiO2) was added to compensate the temperature coefficient of frequency (TCF). Larger achievable strain was verified before the onset of Duffing nonlinearity, providing increased modulation of the Fe0.5Co0.5/Ag and a resolution of 1.11 nT/√Hz, an 86% improvement when compared to a long tether device with the same layer stack (8.02 nT/√Hz) and a 78% improvement over the initial (Fe50Co50/Ag) - AlN long tether devices with no SiO2 thermal compensation.WPT measurements were taken using (Fe50Co50/Ag) - AlN magnetoelectric devices. By sending a magnetic field at the device resonance frequency, optimal WPT can be achieved. Devices were packaged with a magnetic bias circuit and the output power was measured. For a device at 7.44MHz, an output power of 126.8 nW and a power density of 1196.2 uW/mm3 is projected when measuring with both electrodes.

English

ISBN: 9798382835563Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

Magnetostrictive materials

Multiferroic Micro-Electromechanical Systems for Magnetic Sensing and Wireless Power Transfer in Biomedical Applications /
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520 $a Multiferroic micro-electromechanical systems (MEMS) enable small, room temperature, low power magnetic sensing and wireless power transfer (WPT) in biomedical applications.This thesis presents the theory, design, microfabrication, and characterization of multiferroic MEMS magnetic sensors and WPT devices. Iron cobalt/silver (Fe50Co50/Ag) magnetostrictive material is coupled to piezoelectric aluminum nitride (AlN) to form a multiferroic sensor. Low frequency biomagnetic signals are upconverted around the length-extensional beam's 7-16 MHz mechanical resonance to provide Q enhancement to the sensitivity. The up conversion exploits a nonlinear phenomenon of magnetostrictive materials with applied mechanical strain. For two devices studied, modulated sensitivities of 58.4 mA/T and 37.7 mA/T were observed along with resolutions of 5.03 nT/√Hz and 2.72 nT/√Hz over a bandwidth larger than the biomagnetic frequency spectrum (0.1Hz to 1kHz). The sensors' sensitivity was limited by Duffing nonlinearity and the relatively low piezoelectric coefficients of AlN.To improve sensitivity, magnetoelectric sensors were fabricated using (Fe0.5Co0.5)0.92Hf0.08 coupled to 28% aluminum scandium nitride (Al0.72Sc0.28N). Increasing sensitivity improved the resolution from 5.03 nT/√Hz to 2.16 nT/√Hz. To delay the onset of thermal Duffing nonlinearity, various anchoring tether lengths were explored in Fe0.5Co0.5/Ag - AlN magnetoelectric sensors to provide better heat conduction away from the structure. Also, silicon dioxide (SiO2) was added to compensate the temperature coefficient of frequency (TCF). Larger achievable strain was verified before the onset of Duffing nonlinearity, providing increased modulation of the Fe0.5Co0.5/Ag and a resolution of 1.11 nT/√Hz, an 86% improvement when compared to a long tether device with the same layer stack (8.02 nT/√Hz) and a 78% improvement over the initial (Fe50Co50/Ag) - AlN long tether devices with no SiO2 thermal compensation.WPT measurements were taken using (Fe50Co50/Ag) - AlN magnetoelectric devices. By sending a magnetic field at the device resonance frequency, optimal WPT can be achieved. Devices were packaged with a magnetic bias circuit and the output power was measured. For a device at 7.44MHz, an output power of 126.8 nW and a power density of 1196.2 uW/mm3 is projected when measuring with both electrodes.
546 $a English
590 $a School code: 0175
650 4 $a Electrical engineering. $3 649834
650 4 $a Applied physics. $3 3343996
650 4 $a Electromagnetics. $3 3173223
650 4 $a Materials science. $3 543314
650 4 $a Mechanics. $3 525881
653 $a Magnetostrictive materials
653 $a Multiferroic micro-electromechanical systems
653 $a Multiferroics
653 $a Piezoelectrics
653 $a Wireless power transfer
653 $a Aluminum nitride
690 $a 0544
690 $a 0346
690 $a 0794
690 $a 0215
690 $a 0607
710 2 $a University of Pennsylvania. $b Electrical and Systems Engineering. $e degree granting institution. $3 3820714
720 1 $a Olsson, Roy H., III $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 85-12B.
790 $a 0175
791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31294251