자료유형  

 학위논문

Control Number  

0017161618

International Standard Book Number  

9798382835563

Dewey Decimal Classification Number  

621.3

Main Entry-Personal Name  

D'Agati, Michael J.

Publication, Distribution, etc. (Imprint  

[S.l.] : University of Pennsylvania., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

223 p.

General Note  

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

General Note  

Advisor: Olsson, Roy H., III.

Dissertation Note  

Thesis (Ph.D.)--University of Pennsylvania, 2024.

Summary, Etc.  

요약Multiferroic 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.

Subject Added Entry-Topical Term  

Electrical engineering.

Subject Added Entry-Topical Term  

Applied physics.

Subject Added Entry-Topical Term  

Electromagnetics.

Subject Added Entry-Topical Term  

Materials science.

Subject Added Entry-Topical Term  

Mechanics.

Index Term-Uncontrolled  

Magnetostrictive materials

Index Term-Uncontrolled  

Multiferroic micro-electromechanical systems

Index Term-Uncontrolled  

Multiferroics

Index Term-Uncontrolled  

Piezoelectrics

Index Term-Uncontrolled  

Wireless power transfer

Index Term-Uncontrolled  

Aluminum nitride

Added Entry-Corporate Name  

University of Pennsylvania Electrical and Systems Engineering

Host Item Entry  

Dissertations Abstracts International. 85-12B.

Electronic Location and Access  

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Control Number  

joongbu:655009