Design and Analysis of Compact Dual-band Antenna System for Scalp and Skin Implantation

Abstract

This article proposes a compact dual-band circular-shaped implantable antenna for scalp and skin implantation applications. The proposed antenna covers the 1.395-1.432 GHz Wireless Medical Telemetry Service (WMTS) band and 2.4-2.48 GHz Industrial, Scientific, and Medical (ISM) band with a compact volume of 0.0000017λ 3 0 . The antenna maintains a realized peak gain of −24.5 dB and −20.6 dB, respectively, at 1.43 GHz and 2.44 GHz. Moreover, the gain pattern of the antenna is in the off-body direction which is a desirable feature for implantable scenario. It also depicts stable responses under different implantation scenarios. Moreover, the via free configuration is an advantageous feature of the proposed antenna in the context of fabrication complexity. Furthermore, a holistic design approach is considered with integrated components for device-level architecture. The resonance behavior of the proposed antenna structure is also analyzed by developing a conceptual equivalent circuit model. The evaluated specific absorption rate (SAR) complies with the regulated human safety standard. The biotelemetry link capability is also evaluated through the link margin (LM) calculation of the proposed antenna and is able to establish a communication link at a range of 4.5 m distance. INTRODUCTIONThe advancement in technology has considerably influenced humans' day-to-day life. In recent times, the development of biomedical devices for human health monitoring has received considerable attention [1][2][3][4][5][6]. These biomedical devices have been broadly categorized into two different categories: (1) wearable and (2) implantable/ingestible devices where the antenna has a pivotal role to play [2,3]. Apart from wearable medical devices, researchers have taken a keen interest in the design and development of implantable medical devices (IMDs). In this regard, it is essential to note that IMDs have been developed for sensing, monitoring, stimulation, and drug delivery to improve the quality of human life [3,4]. These devices assist in patients' diagnostic and therapeutic purposes [3]. The wireless IMDs with biotelemetry functionalities are beneficial with the integration of modern communication technology [3][4][5]. The wireless IMDs comprise different components, including battery, electronic circuitry, sensor, and implantable antenna.In this context, it is worth noting that an efficient implantable antenna plays a vital role in establishing reliable communication between the IMD and external control unit. It should be noted that, unlike the traditional antenna for free-space application, designing an implantable antenna involves many challenging factors such as miniaturization, operating frequencies, specific absorption rate (SAR) for human safety, and biocompatibility with human tissue [4][5][6]. In this context, antenna miniaturization with desired characteristics is one of the main challenges as the space available for antenna placement in the compact implantable device is limited. In the recent past, researchers have propose...