Fig 1.
Illustration of wireless ENIs for neural stimulation and recording with helical (left) or planar (right) coils.
Table 1.
Wireless endovascular devices reported in the literature.
Fig 2.
The design requirements for different types of endovascular devices.
Table 2.
Potential vessels for ENI implantations.
Fig 3.
Wireless link simulation and measurement at 10 MHz.
COMSOL simulation of magnetic field induced by the designed (a) planar Tx designed for planar Rx, (b) flux-pipe Tx designed for helical Rx, and (c) figure-8 Tx for helical Rx. Red lines indicating the magnetic field lines and colored solids represent ferrites. (d-f) k versus inter-coil distance calculated from simulation (lines), tissue measurements (dots), and in-vivo measurements (triangles). Error bars indicate the uncertainties of implant distances. Scale bar = 10 mm.
Fig 4.
Coil measurements across frequency sweeps.
of the (a) planar Rx coil and the (b) helical Rx coil, measured in air (solid lines) and in tissue (dashed lines). (c) Rx and Tx coil prototypes.
of the (d) planar Tx coil, the (e) flux-pipe Tx coil (e), and the (f) figure-8 coil, measured in air (solid lines) and in tissue (dashed lines).
of the (g) planar-planar pair, the (h) helical-flux-pipe pair (h), and the (i) helical-figure-8 pair, measured in air (solid lines) and in tissue (dashed lines).
Fig 5.
Optimal PTE from simulation (lines), tissue measurements (dots), and in-vivo measurements (triangles), for the three coil pairs versus inter-coil distance.
Error bars indicate the uncertainties of implant distances. Copper wires and ferrites were selected for all three Tx coil shapes. Operational frequencies were set at 13.56 MHz for the planar-planar pair and helical-figure-8 pair, and at 6.78 MHz for the helical-flux-pipe pair.
Fig 6.
SAR simulations for the three coil pairs at each’s operational frequency.
(a) The normalized SAR distribution in Sim4Life simulation. (b) SAR versus inter-coil distance for 10 mW PDL. (c) Maximum PDL versus inter-coil distance under 1.6 mW/g SAR. Scale bar = 10 mm. All conditions were the same except for the operating frequencies were chosen for the highest efficiency for each coil pair.
Fig 7.
Misalignment investigations for the three coil pairs at each’s operational frequency.
(a) PDL versus rotational misalignment of the planar Rx coils, and (b) PDL versus tilting misalignment for planar and helical Rx coils from simulation (lines), tissue measurements (dots), and in-vivo measurements (triangles). The power source is set to 500 mW and the inter-coil distance is fixed to 20 mm.
Fig 8.
Load matching simulation with different coil turns.
(a) Rx coil prototypes with 2, 4, and 6 turns for planar Rx and 10, 20, 30 turns for helical Rx. Load resistance versus PDL at 13.56 MHz (b) for different turns of planar Rx with planar Tx, (c) for different turns of helical Rx with flux-pipe Tx at 6.78 MHz, and (d) for different turns of helical Rx with figure-8 Tx at 13.56 MHz. The power source was set to 500 mW and the inter-coil distance was fixed to 20 mm.