An Implantable Antenna Sensor for Medical Applications

Pathological changes of human tissues, such as tumors, can cause changes in the dielectric properties of the tissues. Based on this characteristic, we propose an implantable antenna sensor and study its radiation and sensing performance in breast tumor recurrence diagnosis in the 2.45 GHz Industrial, Scientific, and Medical (ISM) band. The antenna sensor shows the advantage of miniaturization with a volume of 13.2mm ³ by employing an S-shape monopole antenna and a closed loop. The simulated results show that the antenna sensor has a good radiation pattern with peak gain values of -8.4 and -17.9dBi in normal and malignant breast tissue, respectively. Furthermore, the antenna sensor exhibits good sensitivity to the dielectric properties of breast tissue. When the permittivity increases by 10, the resonance frequency decreases between 9-18MHz. To verify the simulated results, the sensing properties and the radiation patterns of the implantable antenna sensor were measured in the pork and tissue-mimicking liquid. The measured results are consistent with the simulated ones. Hence, the proposed antenna can be used as a wireless sensor to monitor pathological changes of human tissues, such as breast tumors.