A Miniaturized Dual-Band Implantable Antenna System for Medical Applications

In this communication, a biotelemetry device for scalp implantation is proposed with an ultraminiaturized and simple-structured implantable antenna that exhibits dual-band characteristics in the industrial, scientific, and medical bands (915 MHz and 2.45 GHz). The proposed system incorporates two batteries and microelectronic components in a total volume of 434.72 mm³. The recommended antenna has a reduced volume of 9.8 mm³ (7 mm <inline-formula> <tex-math notation="LaTeX">$\times7$ </tex-math></inline-formula> mm <inline-formula> <tex-math notation="LaTeX">$\times0.2$ </tex-math></inline-formula> mm), which is the smallest antenna presented so far. In homogeneous and heterogeneous environments, the designed antenna system has peak gain values of −28.04 and −28.94 dBi, respectively, at 915 MHz, and −23.01 and −23.06 dBi, respectively, at 2.45 GHz. For validation, the prototype of the antenna and corresponding system are immersed in a 3-D head phantom (saline solution), and the measured results are found in close agreement with the simulation results. Additionally, the data communication range is analyzed through a link budget calculation at several data rates and an input power of −16 dBm. The radiation of the antenna system in the two principal planes (E and H) are similar to being omni-directional and directed away from the anatomical human body model as mandatory for the telemetry applications. Hence, the proposed antenna system can be employed in scalp implantation, especially for intracranial pressure monitoring.