David Arnold's Research Group

We seek to develop a platform that allows magnetic field sensing using a small footprint, in the absence of an external power supply. Our approach uses magnetoelectric nanofibers to create a zero-power magnetic field sensor. The challenge is to develop methods to assemble these materials into devices that leverage their unique anisotropic properties.

The figure of merit for magnetoelectric materials is the magnetoelectric coefficient, a measure of the amount of voltage generated with respect to the magnitude of the applied magnetic field. Bulk magnetoelectrics and thin films are limited by defects and substrate clamping respectively.  To overcome the limitations of thin-film based composite magnetoelectrics we have developed magnetoelectric bilayer structures on a single nanofiber, i.e., 1D magnetoelectrics. These materials are theoretically predicted to have magnetoelectric coupling coefficients that are orders of magnitude greater than their thin film counterparts. 

Magnetoelectric materials can be employed in a wide variety of applications including magnetic field sensors and tunable resonance energy harvesters.  By optimizing for material system and architecture, drastic increases in magnitude of voltage generated with decreased size can be achieved. This could allow for more sensitive magnetic field sensors appropriate for a wider array of applications and decreased size to allow for easier integration into ICs.
 

As predicted by Moore's "law", the past few decades have seen massive reductions in the size of integrated circuits, enabling the portable, handheld devices now in everyday use. However, the components that power these devices have not experienced a similar size reduction. For example, the power adapter of a laptop computer is only modestly smaller than that two decades ago, and the printed circuit board inside a smart phone must dedicate between 20% and 40% of the board area for power conversion and management. To date, efforts towards miniaturization have been limited by both materials and manufacturing challenges. To address this gap, this research will study nanomanufacturing processes to facilitate the scalable synthesis of high quality magnetic nanoparticles and nanocomposite core materials and the fabrication of compact power inductors and transformers through assembly of these nanomaterials in a manner that is compatible with current manufacturing processes, such as silicon wafer or printed circuit board fabrication. This compatibility will enable fully integrated and compact system-on-chip or system-in-package power solutions. This research will be accomplished by fostering collaboration among disciplines including materials science, chemical engineering and electrical engineering. It will foster diversity in the profession by involving high school and undergraduate students in research activities and by broadening participation through the inclusion and engagement of women and underrepresented groups.

There is an increasing demand for wireless power charging of mobile electronic devices, electric vehicles, biomedical implants and IoT sensor networks. Many of the already available wireless power transmission systems are based on inductive coupling and the size ranges in the cm’s scale, linked to the large surface area requirement. A competing technology is based on an RF approach, with small size chip but impractical power levels of pW to µW, and efficiency close to unity. The alternative working principle that we propose results in a more compact solution that can be reduced to mm’s chip size while producing reasonable output power (1 mW range) at low frequency ranges (50 Hz to 1 kHz).

We have developed an electrodynamic wireless power transmission (EWPT) system that relies on the magnetic-to-mechanic-to electrical conversion from a transmitter to a remote resonator, through electrodynamic transduction. The mechanical motion of a permanent magnet is converted into electrical power, when the magnet is set in motion/rotation, by a time-varying magnetic field, next to the receiver windings.