Wireless Power Transfer to Implantable Medical Devices With Multi-Layer Planar Spiral Coils

Applications Of Wpt In Implantable Medical Devices

The design of WPT systems for an implantable device relies heavily on the application characteristics. For instance, recharging a battery, or powering devices, which uses current stimulation of the tissue as a way of therapy such as DBS require high instantaneous power. Such high power can stress the tissue if it causes temperature increases beyond the safety limits. In other applications such as cochlear implants, where the primary coil stays on continuously, albeit providing only a fraction of the current, the sizes of both primary and secondary coils are of primary concerns (Zeng, Rebscher,Harrison, Sun, & Feng, 2008). Additionally, the properties of the underlying tissue should also be carefully analyzed and taken into account when designing the WPT. In many cases, the WPT is used in a dual role as a telemetry system, or it may need to coexist with a telemetry system. The co-design of these two systems adds additional limits on the system design on parameters such as bandwidth and quality factor. Finally, various regulatory issues must be cleared to have an implantable biomedical device to be used in a clinical setting; imposing further constraints on the device design.

In the following paragraphs, exemplary IMDs are discussed to better assess the requirements and limitations of IMDs for different applications. Note that these examples are by no means an exhaustive list of IMDs, and such a discussion is beyond the scope of this chapter. Interested readers can refer to Agarwal, Jegadeesan, Guo, and Thakor (2017) for an up-to-date and extensive review of WPTs for IMDs.