Electrically-Small Antenna With Low SAR for Scalp and Deep Tissue Biomedical Devices

Abstract

An ultra-miniaturized implantable antenna for scalp and deep tissue implants operating in the Industrial, Scientific, and Medical (ISM) frequency band is proposed in this communication. The proposed antenna has a compact size of only 4.422 mm 3 (3.45 × 3.4 × 0.377 mm 3 ). A meandered patch backed by a full ground plane was used to implement the proposed ultra-miniaturized antenna. The full ground plane does not allow backward energy flow, thus ensuring patient safety. The performance of the proposed antenna was evaluated in three different simulation environments: homogeneous skin phantom (HSP), skin implant multilayer phantom (SIMP), and muscle implant multilayer phantom (MIMP) models with and without a dummy implantable wireless device (IMD). These models were considered to evaluate the performance of the proposed antenna in more realistic complex human body environments. The proposed antenna demonstrated excellent impedance matching performance at the ISM band with a measured -10 dB impedance bandwidth of 260 MHz (2,249-2,511 MHz). The effects of coaxial cable on antenna performance were also studied. The proposed antenna exhibited a maximum measured peak gain of -26.54 dBi. Furthermore, the 1-g and 10-g specific absorption rate (SAR) values were calculated and satisfied the safety guidelines. A reliable communication link up to distances of 15, 4, and 1.3 m for bit rates of 7 kbps, 100 kbps, and 1 Mbps, respectively, can be established between the implantable device and external base station. Finally, a sensitivity analysis of the proposed antenna was conducted showing that the proposed implantable antenna can efficiently work under varying tissue conditions.

A metamaterial unit-cell based patch radiator for brain-machine interface technology

“…It is sufficient for an implantable antenna to transmit data at speeds of = 7 Kbps or 100 Kbps [ [ 32 ]]. Additionally, a link margin of 15 dB is considered adequate for practical applications [ [ 12 ]].…”

Survey of near-field wireless communication and power transfer for biomedical implants

“…As a result, one of the most difficult challenges to overcome in achieving a higher-quality factor for an implant coil to produce satisfying PTE. In [163], The authors demonstrated that the greatest measured peak gain is 26.54 dBi. In addition, the specific absorption rate (SAR) values for 1 g and 10 g were calculated and met safety standards.…”

Design and Optimization of a Mid-Field Wireless Power Transfer System for Enhanced Energy Transfer Efficiency

“…A meandering antenna is the best candidate and prime choice for an implantable antenna for various reasons. This technique offers numerous benefits, including compactness and space efficiency, an extended operative length, improved impedance matching, and reduced electromagnetic interference [28]. The design, optimization, and miniaturization of the proposed antenna are accomplished through several steps, outlined as steps 1-5 and illustrated in Figure 3.…”