Miniaturizing wireless implants.

The article discusses two wireless modalities, the far-field and near-field, terms that refer to the distance between the source and the device as a function of the powering frequency. Also discussed is the new mid-field wireless power transfer technique which enables the highest power transfer efficiency at deep implantation depths compared with far-field and near-field techniques. Full-wave analytical and numerical techniques have been used to derive the optimum frequency and current density.