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Wireless sub-mm sized distributed brain implants have been proposed as the next frontier of Brain-Machine Interface (BMI) design to achieve untethered, high-density neural recording and stimulation. Simultaneously improving the wireless power transfer (WPT) efficiency and reducing the specific absorption rate (SAR) will be crucial for its clinical success. Towards these goals, we present an EM simulation method, a lumped equivalent circuit model, and a theoretical analysis to accurately predict the power delivered to the recording/ stimulating nodes, as well as the power dissipated in biological tissues and all other lossy elements within the system. This comprehensive framework also explains how increasing the distance between the transmit coil and the scalp can beneficially reduce the SAR without undermining the WPT efficiency. This work presents a rigorous prediction technique for transmission loss and tissue heating towards performance optimization.
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This content will become publicly available on January 7, 2026
Metamaterial Antenna Design to Enhance Near Field Inductive Coupling for Biomedical Implants
This paper presents a concept for a double negative metamaterial (DNM)-based antenna to simultaneously enhance Wireless Power Transfer (WPT) and reduce Specific Absorption Rate (SAR) here for a network of distributed brain microimplants. The DNM copper coils are integrated in a FR-4 substrate, which has a dielectric constant of 4.3 and tangent loss (δ) of 0.025. Occupying a 2 × 2 cm2 area, the DNM structure is introduced into our target wireless brain-machine interface (BMI) system operating at 915 MHz. Preliminary HFSS simulations show it provides 2 dB WPT enhancement and a 20% SAR reduction. We believe the work has the potential to address the WPT/ SAR co-optimization challenges for biomedical implants in general.
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- Award ID(s):
- 2322601
- PAR ID:
- 10597863
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 978-1-946815-20-0
- Page Range / eLocation ID:
- 231 to 232
- Format(s):
- Medium: X
- Location:
- Boulder, CO, USA
- Sponsoring Org:
- National Science Foundation
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