Optimal frequencies for inductive powering of fully implantable biosensors for chronic and elderly patients

Abstract

Abstract-The paper aims at exploring advantages and drawbacks of using high-frequency inductive links to transmit power wirelessly to implanted biosensors. A system with an external transmitting coil located into a skin patch and a receiving coil embedded into a fully implanted biosensor is simulated. The effects of the geometry of the coils on the optimal working frequencies and on the power gain have been analyzed. For applications dedicated to elderly and chronic patients, attention has been posed to the effects on link efficiency of different implantation sites and possible misalignments between the coils.

A Study of Multi-Layer Spiral Inductors for Remote Powering of Implantable Sensors

“…Four different locations, such as arm, forearm, abdomen, and leg have been explored with the Visible Human Server and modeled using the Cole-Cole dispersion model [32]. The description of the tissues within these implantation areas is reported in Table I, together with the location of the coils.…”

“…The differences among the three curves are mostly due to the different implantation depths. Reprinted from [32]. timal frequency shifts down in the range of frequencies where absorption is minimum (Fig.…”

“…3, from [32], where the link efficiencies of three pairs of small-size, single-turn inductors are compared. The receiving coils are single-turn, rectangular structures with copper metal traces.…”

“…The electrical properties of the body tissues are determined for different implantation areas [32] (Section IV-A). Those data are used to simulate the effects of the inductor geometry on the optimal working frequency [32] (Section IV-B). Once a range of working frequencies is defined, the effects of the geometry on the link efficiency and the voltage gain are measured (Section IV-C).…”

IronIC patch: A wearable device for the remote powering and connectivity of implantable systems

“…The width of the copper traces is 250 µm. The geometry of the external inductor strongly influences the efficiency of the link [9]. The geometry used is a good tradeoff between link efficiency (ratio between the power dissipated on the load and the total power dissipated) and voltage gain (ratio between the voltage supplied to the load and the voltage source).…”