Tissue-dependent Co-matching Method for Dual-mode Antenna in Implantable Neurostimulators

A dual-mode antenna with cooperative matching (co-matching) was designed for implantable neurostimulators functioning within the Medical Implant Communications Service (MICS) band. In the proposed matching method, the first and third modes of a spiral monopole were appropriately designed and cooperatively matched for the patients with different body shapes. For obese patients, the neurostimulator was implanted in the fat layer (low permittivity), operating in the first mode. For slim patients, the neurostimulator was placed around the muscle tissue (high permittivity), operating in the third mode. Although there were different modes of operation in modified environments, the antenna was consistently well matched using a single lumped inductor to cover the desired band. The proposed matching strategy was validated by experiments, which followed the findings of our simulation data, exhibiting potential applications for implantable neurostimulators in different body types.