An Ultra-Miniaturized Antenna with Ultra-wide Bandwidth Characteristics for Medical Implant Systems

In this study, an ultra–miniaturized implantable antenna based system with ultra-wideband characteristics in the industrial, scientific, and medical band (i.e., 2.4–2.48 GHz) is proposed for biomedical applications. A biocompatible and flexible liquid crystalline polymer material, Rogers ULTRALAM (tan $\delta =0.0025$ and $\varepsilon _{r} =2.9$ ), is employed as both the substrate and superstrate. The proposed antenna with a compact size ( $7\times 7\times0.2$ mm3) and a wide bandwidth (1533 MHz), was primarily designed for overcoming the detuning challenges that may occur owing to the electronic circuitry and irregularity as well as inhomogeneity of the human tissue environment. The miniaturization of this antenna was achieved by introducing a shorting pin and open-ended cuts in the ground plane, as well as in the radiating patch. The proposed antenna also yielded a higher gain and lower specific absorption rate (SAR). Through the link budget analysis, it was observed that 1 Mbps of data could be easily transmitted over a distance of 15 m. The simulated and in vitro measured results confirmed that compared to the recently reported antenna systems, our proposed ultra-wideband antenna based system could work more efficiently in the complex environment of the human body, thus establishing itself as an attractive candidate for biomedical applications.