A Compact, Enhanced Gain and Dual Band Antenna Array for a Cardiac Loop Recorder Device

Abstract

An implantable cardiac loop recorder (ICLR) is a compact device that detects arrhythmias and syncope by continuously monitoring the heart’s electrical activity. The present research introduces a compact enhanced gain 4 × 2 antenna array for an ICLR device to transmit heart health data to remote physicians. The antenna array has a compact footprint of 4 mm × 7 mm and provides dual-band biotelemetry at the industrial, scientific, and medical (ISM) frequencies of 2.4 GHz and 5.8 GHz. In the simulation environment, the ICLR integrated antenna array is designed by implanting under the skin of a skin-blood-fat-muscle canonical chest phantom model and a 3D homogeneous human body model. The performance of the designed antenna array is experimentally evaluated in a gel-based skin phantom and minced pork. The simulated and measured gain values at 2.4 GHz are −17.82 dBi and −20.1 dBi, while at 5.8 GHz are −9.5 dBi and −12.3 dBi, respectively. The literature review highlights that the novelty of this research lies in a compact dual-band implantable antenna, with enhanced gain achieved through a 4 × 2 array design incorporating two distinct ultra-compact antenna elements. The achieved gain is higher than previously reported implanted antennas of comparable footprints. The authors additionally investigated the impact of different biological layers on the propagation of the antenna’s transmitted wave inside the human body, which was not discussed in prior studies on implantable antennas. The link margin indicates that the proposed ICLR biotelemetry antenna can effectively communicate up to 5 meters of distance at 10 Mbps data rates non-line of sight communication scenarios.