Abstract |
The use of wireless communication using inductive links to transfer data and
power to implantable microsystems to stimulate and monitor nerves and muscles is
increasing. This paper deals with the development of the theoretical analysis
and optimization of an inductive link based on coupling and on spiral circular
coil geometry. The coil dimensions offer 22 mm of mutual distance in air.
However, at 6 mm of distance, the coils offer a power transmission efficiency of
80% in the optimum case and 73% in the worst case via low input impedance,
whereas, transmission efficiency is 45% and 32%, respectively, via high input
impedance. The simulations were performed in air and with two types of simulated
human biological tissues such as dry and wet-skin using a depth of 6 mm. The
performance results expound that the combined magnitude of the electric field
components surrounding the external coil is approximately 98% of that in air,
and for an internal coil, it is approximately 50%, respectively. It can be seen
that the gain surrounding coils is almost constant and confirms the
omnidirectional pattern associated with such loop antennas which reduces the
effect of non-alignment between the two coils. The results also show that the
specific absorption rate (SAR) and power loss within the tissue are lower than
that of the standard level. Thus, the tissue will not be damaged anymore. |