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https://hdl.handle.net/2142/107242
Description
Title
Ferrofluid-core S-RuM microelectronic inductors
Author(s)
Kraman, Mark D.
Contributor(s)
Li, Xiuling
Issue Date
2020-05
Keyword(s)
Inductors
Capacitors
Passive
Microelectronics
Microfabrication
Strain
Abstract
Integrated planar inductors suffer from the performance limitations of their thin film cores, including
eddy current losses, hysteresis losses, and low ferromagnetic resonance frequencies. Despite
past and potential magnetic material advances, the utilization of these materials is poor given the
architecture and fabrication technology for integrated inductors. As power module miniaturization
innovation requires inductor components that operate at high frequencies, inductor technology
has lagged due to the fundamental positive scaling of a solenoid’s inductance with loop area. The
integration of ferrofluids as a core material for the Self-Rolled-up SiNx Membrane (S-RuM) platform
circumvents and alleviates these problems, realizing the advantages of magnetic nanoparticles in
this application. The S-RuM inductor platform uniquely provides a cylindrical cavity through which
the device’s magnetic field flows, ideal to host a fluid core stabilized by capillary force. Ferrofluids
are colloidal suspensions of magnetic nanoparticles, which display superparamagnetism and whose
magnetization can rapidly rotate spontaneously under sufficient thermal conditions according to
their Néel relaxation time. In this work, the performance characteristics of S-RuM power inductors
filled with two different ferrofluids, a commercial ferrofluid and custom-synthesized ferrofluids, are
compared, and the engineering physics of a ferrofluid specialized for the proposed application are
considered.
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