Keywords

Piezoelectric Transformer, Bulk Resonators, MEMS Transformer, Lithium Niobate

Abstract

This work presents piezoelectric transformers for compact electronics and atmospheric plasma generation, utilizing thin-film microelectromechanical systems (MEMS) and bulk machined suspended transformers based on 128˚ Y-cut lithium niobate. As electronic devices continue to miniaturize, scaling down magnetic components remains a challenge due to difficulties in generating and confining sufficiently large magnetic fields. The most common configurations exhibit efficiencies of approximately 70% and can cause interference in surrounding electronics. In this work, thin-film flexural mode piezoelectric transformers are developed for on-chip, low frequency passive voltage gain and impedance transformation. These devices exhibit efficiencies as high as 95% and voltage gain above unity for large capacitive loads (>2 nF). Nanosecond 1064 nm pulsed laser ablation is demonstrated as a method for deep etching of bulk lithium niobate substrates with microscale features. This technique enables the fabrication of a series of bulk lithium niobate transformers for passive voltage gain, impedance transformation, and plasma generation. The Rosen transformer, traditionally a mechanically mounted device, is reimagined as a suspended structure with acoustic reflectors and tethers. This resulted in the smallest Rosen Transformers developed, possessing record-high quality factors. These implementations demonstrate a measured voltage gain of 50 in atmospheric conditions and can excite stable non-thermal atmospheric plasma glow discharges with less than 33 mW of input power, the lowest ever reported. Finally, a planar Lamé mode piezoelectric transformer using 128˚ Y-cut lithium niobate is demonstrated. While the Lamé mode cannot be excited in most piezoelectric materials, this work shows an efficient mechanism of transduction in this specific cut of lithium niobate. The device exhibits a measured open-circuit voltage gain of approximately 100 in atmospheric conditions with a peak efficiency greater than 99%. The device can generate atmospheric plasma discharges and driving full-bridge rectifiers, indicating its potential for use in DC-DC switching power supplies and compact plasma generation.

Completion Date

2024

Semester

Fall

Committee Chair

Reza Abdolvand

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Electrical and Computer Engineering

Format

PDF

Identifier

DP0029701

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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