Magnetoelectric Antennas: From Bulk Resonators to Exchange-Biased, High-Efficiency Devices

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Contents of the Talk

Antennas are a fundamental component of modern wireless systems, enabling communication across applications ranging from mobile phones and Internet-of-Things (IoT) devices to emerging biomedical implants. As these technologies continue to shrink in size while demanding reliable wireless connectivity, the development of highly miniaturized antennas becomes increasingly critical—particularly for space-constrained and power-limited platforms such as implantable medical devices.

Magnetoelectric (ME) antennas have recently emerged as a highly promising alternative to conventional electromagnetic antennas. These devices leverage strain-mediated coupling between piezoelectric and magnetostrictive layers to enable radiation at acoustic resonance frequencies, allowing antenna dimensions that are approximately five orders of magnitude smaller than their electromagnetic counterparts. Since their first demonstration in 2017, substantial progress has been made over the past eight years. Early bulk acoustic resonator–based devices have evolved into mechanically robust, solidly mounted resonators fabricated directly on substrates, significantly improving reliability and integrability. Further developments include ME antenna arrays and the multifunctional use of these devices as both antennas and energy harvesters.

Despite these advances, improving radiation efficiency remains a key challenge. While increasing the thickness of magnetostrictive layers can enhance performance, it also shifts the resonant frequency and introduces significant fabrication complexity. To address these limitations while maintaining the same device geometry and dimensionality, we introduce exchange-biased magnetoelectric antennas. The incorporation of exchange bias stabilizes the magnetic layer by suppressing magnetic domain wall motion and reducing magnetic noise, which directly enhances strain-mediated transduction. As a result, the exchange-biased ME antennas exhibit a twofold improvement in transmission and nearly an order-of-magnitude increase in efficiency. This performance enhancement translates to a tenfold reduction in the required power budget, making these antennas particularly attractive for ultra-low-power, space-constrained applications such as implantable medical devices, where battery charging is difficult and replacement is often impractical.

Short CV

Prasanth Velvaluri is a researcher from India. He earned his bachelor’s degree in mechanical engineering and a master’s degree in materials science and engineering at Kiel University, Germany, where he also completed his PhD between 2017 and 2021 as part of the GRK “Materials for Brain” Research Training Group. His doctoral research focused on the development of stents for the treatment of brain aneurysms.

Following his PhD, he continued his work at Kiel University from 2022 to 2024. As a recipient of the Feodor Lynen Research Fellowship from the Alexander von Humboldt Foundation, he spent one year at Northeastern University in Boston working on magnetoelectric antennas. Since 2025, he has been a postdoctoral researcher on a DFG-funded project developing self-folding, origami-based biomedical implants, with a research focus on integrating magnetoelectric materials into implantable substrates for next-generation biomedical devices.