We analyze physics-driven trade-offs across
915 MHz, 2.4 GHz, 5.8 GHz, 28 GHz, and 60 GHz for RF neural
interfaces. Using skin depth, diffraction-limited resolution,
and coherence-time–limited control, we quantify: (i) sub-GHz
achieves ∼18.6 mm penetration versus ∼3.36 mm (28 GHz)
and ∼2.30 mm (60 GHz), a ∼6–8× depth difference; (ii)
mmWave offers ∼31× finer λ/2 resolution than sub-GHz
at equal aperture; and (iii) robustness exp(−Ts/Tc) drives
hard real-time budgets (Ts<5 ms at mmWave; Ts>50 ms is
tolerable at sub-GHz). We provide design guidance for depth–
precision–latency selection and discuss safety and modeling
caveats.
Radio frequency systems for neural sensing and modulation
operate across a wide spectrum from sub-GHz Industrial, Scientific and Medical (ISM) bands to millimeter-wave frequencies
exceeding 60 GHz. Each frequency regime offers distinct advantages: lower frequencies penetrate deeper into tissue but provide
coarse spatial resolution, while higher frequencies enable precise
targeting at shallow depths [1].
The fundamental physics of electromagnetic propagation in
lossy biological media creates inherent trade-offs that constrain
system design. Understanding these trade-offs is critical for
optimizing neural interface performance while maintaining safety
margins and control system stability