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  1. Free, publicly-accessible full text available January 1, 2023
  2. Abstract

    Electrical stimulation via invasive microelectrodes is commonly used to treat a wide range of neurological and psychiatric conditions. Despite its remarkable success, the stimulation performance is not sustainable since the electrodes become encapsulated by gliosis due to foreign body reactions. Magnetic stimulation overcomes these limitations by eliminating the need for a metal-electrode contact. Here, we demonstrate a novel microfabricated solenoid inductor (80 µm × 40 µm) with a magnetic core that can activate neuronal tissue. The characterization and proof-of-concept of the device raise the possibility that micromagnetic stimulation solenoids that are small enough to be implanted within the brain may prove to bemore »an effective alternative to existing electrode-based stimulation devices for chronic neural interfacing applications.

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  3. Most of the next-generation implantable medical devices that are targeting sub-mm scale form factors are entirely powered wirelessly. The most commonly used form of wireless power transfer for ultra-small receivers is inductive coupling and has been so for many decades. This might change with the advent of novel microfabricated magnetoelectric (ME) antennas which are showing great potential as high-frequency wireless powered receivers. In this paper, we compare these two wireless power delivery methods using receivers that operate at 2.52 GHz with a surface area of 0.043 mm2 . Measurement results show that the maximum achievable power transfer of a MEmore »antenna outperforms that of an on-silicon coil by approximately 7 times for a Tx-Rx distance of 2.16 and 3.3 times for a Tx-Rx distance of 0.76 cm.« less
  4. Controlling magnetization dynamics is imperative for developing ultrafast spintronics and tunable microwave devices. However, the previous research has demonstrated limited electric-field modulation of the effective magnetic damping, a parameter that governs the magnetization dynamics. Here, we propose an approach to manipulate the damping by using the large damping enhancement induced by the two-magnon scattering and a nonlocal spin relaxation process in which spin currents are resonantly transported from antiferromagnetic domains to ferromagnetic matrix in a mixed-phased metallic alloy FeRh. This damping enhancement in FeRh is sensitive to its fraction of antiferromagnetic and ferromagnetic phases, which can be dynamically tuned bymore »electric fields through a strain-mediated magnetoelectric coupling. In a heterostructure of FeRh and piezoelectric PMN-PT, we demonstrated a more than 120% modulation of the effective damping by electric fields during the antiferromagnetic-to-ferromagnetic phase transition. Our results demonstrate an efficient approach to controlling the magnetization dynamics, thus enabling low-power tunable electronics.« less