Wide Band Meandered-Loop Ground Radiation Antenna for Biomedical Applications

The concept of wireless implantable medical devices (IMDs) is becoming more popular as the world’s population ages and concerns about public health grow. Implantable antennas have figured prominently in wireless communication among IMDs and external infrastructures, yet they have subsequently become a major study area. Among the most difficult aspects of building implantable antennas is to varied physical tissues and fluids act as dielectric stress on antenna, affecting its efficiency dramatically. Ground radiation antenna was particularly designed for the antenna size reduction. The features of the ground have an impact on it. There is variance in the radiation field with similar frequency and antenna length yet varied ground conductance. It has been discovered that when the ground conductance is low, the radiation field is minimal and the orientation of the radiation field modifies. A meandered-loop ground radiation antenna (MGRA) was designed by coupling the meandered-loop structure to the ground radiating plane using only one electrical element. The proposed antenna was studied for biomedical applications at ISM band in the range between 2.4 to 2.8 GHz. The overall size of antenna is 30×24 mm2 making it suitable for the implantable applications. The bandwidth of the MGRA was further improved by using stub structures. The single layer skin model simulation showed that |S11| parameter as −21.21 dB at the resounding frequency of 2.40 GHz. Major factors like impedance match gain, radiation effectiveness and Specific Absorption Rate (SAR) had also been evaluated in this study.

Small Triple-Band Meandered PIFA for Brain-Implantable Biotelemetric Systems: Development and Testing in a Liquid Phantom

We present a meandered triple-band planar-inverted-F antenna (PIFA) for integration into brain-implantable biotelemetric systems. The target applications are wireless data communication, far-field wireless power transfer, and switching control between sleep/wake-up mode at the Medical Device Radiocommunication Service (MedRadio) band (401–406 MHz) and Industrial, Scientific and Medical (ISM) bands (902–928 MHz and 2400–2483.5 MHz), respectively. By embedding meandered slots into the radiator and shorting it to the ground, we downsized the antenna to the volume of 11 × 20.5 × 1.8 mm3. We optimized the antenna using a 7-layer numerical human head model using full-wave electromagnetic field simulation. In the simulation, we placed the implant in the cerebrospinal fluid (CSF) at a depth of 13.25 mm from the body surface, which is deeper than in most works on implantable antennas. We manufactured and tested the antenna in a liquid phantom which we replicated in the simulator for further comparison. The measured gain of the antenna reached the state-of-the-art values of −43.6 dBi, −25.8 dBi, and −20.1 dBi at 402 MHz, 902 MHz, and 2400 MHz, respectively.

Review on Medical Implantable Antenna Technology and Imminent Research Challenges

Implantable antennas are mandatory to transfer data from implants to the external world wirelessly. Smart implants can be used to monitor and diagnose the medical conditions of the patient. The dispersion of the dielectric constant of the tissues and variability of organ structures of the human body absorb most of the antenna radiation. Consequently, implanting an antenna inside the human body is a very challenging task. The design of the antenna is required to fulfill several conditions, such as miniaturization of the antenna dimension, biocompatibility, the satisfaction of the Specific Absorption Rate (SAR), and efficient radiation characteristics. The asymmetric hostile human body environment makes implant antenna technology even more challenging. This paper aims to summarize the recent implantable antenna technologies for medical applications and highlight the major research challenges. Also, it highlights the required technology and the frequency band, and the factors that can affect the radio frequency propagation through human body tissue. It includes a demonstration of a parametric literature investigation of the implantable antennas developed. Furthermore, fabrication and implantation methods of the antenna inside the human body are summarized elaborately. This extensive summary of the medical implantable antenna technology will help in understanding the prospects and challenges of this technology.

E-shape Metamaterials Embedded Implantable Antenna for ISM-band Biomedical Applications

This paper presents a compact antenna based on two different metamaterial resonators, the E-shape resonators and the interdigital resonators suitable for biomedical implant applications. The proposed antennas operate in the industrial, scientific, and medical (ISM) bands in the frequency band of 2.4–2.5 GHz. The integration of metamaterial (MTM) in the design leading to the reduce size of these antennas and gaining enhancement. The overall size of the proposed antennas is\(8\times 7\times 1.27{\mathbf{m}\mathbf{m}}^{3}\). The implantable antennas contain two layers of the substrate; the lower layer comprises the MTM resonators and the upper, superstrate layer. To order to observe the exposure of electromagnetic energy to human tissues, the specific absorption rates (SARs) of the proposed antennas are also calculated in the layer model. The antennas are designed and simulated by the two software simulators CST and HFSS.