Implant Detection Using Self-Injection-Locked Sensor with Near-Field Split-Ring Resonator

In this work, a self-injection locked (SIL) sensor with the near-field split-ring resonator (SRR) is designed to detect an in-body implant. Since the designed SRR features the beneficial characteristic of focusing the magnetic field beneath the SRR structure, it will reach the deeper area where the implant locates. The change of the implant location will result in a frequency shift of the SIL such that the detection of the lock-in frequency shift can determine the implant depth in the body. The measurement results demonstrate that the designed SIL with 5 dBm power at 900 MHz can detect a 20x20 mm
²
metal plate with a depth change from 5 to 30 mm beneath the liquid phantom surface.