Wideband Miniaturized Flexible On-Skin Antenna for Biomedical Applications

The present paper proposes a novel design of a compact biomedical antenna to be placed touching the skin of human body. The purpose of the proposed on-skin antenna is to launch the microwave into the human body for the purpose of communication with in-body sensors, detection of tumor tissues, or 3D microwave imaging. The antenna structure can be seen as circular patch perforated at its center and surrounded by an external ring. The proposed antenna is fabricated for measurement of S
11
at the input while the antenna surface is touching the skin. The measured frequency response is compared to the simulation results showing good agreement. The antenna impedance is matched over the frequency band 3.6 – 5.5 GHz i.e. the percentage bandwidth is 42% . Moreover, the antenna is compact ( 12.5mm × 14.3mm × 0.5mm) and made of a thin flexible substrate of type Rogers RO3003. The wide frequency band, compact size, and thin flexible material of the substrate makes this antenna a good candidate for the operation as a sensor antenna for biomedical applications including 3D microwave imaging and also for in-body communication. The distribution of the SAR
1g
(specific absorption rate averaged over 1 g) inside the human tissues in the region adjacent to the on-skin antenna is investigated through simulation. To ensure safe level of the electromagnetic exposure while the antenna is being placed on the human body for the purpose of communication, imaging, or tumor detection, it is found, through simulation, that the maximum SAR
1g
does not exceed 1.6 W/g when the input power is not greater than 70 mW.