Design and in‐vivo testing of a low‐cost miniaturized capsule system for body temperature monitoring

Abstract

This article presents a stacked dipole antenna operating at industrial, scientific, and medical‐band (902‐928 MHz) for ingestible temperature monitoring applications. To date, the proposed capsule system has a smaller dimension of 11 mm (diameter) × 16 mm (length) compared to other existing capsule systems. To achieve size reduction of the capsule system, the conjugating matching method is utilized and the matching circuits are intended to be removed. The whole capsule system is simulated in a one‐layer muscle phantom for initial parameters optimization, and the impedance bandwidth ranges from 908 to 924 MHz, which is sufficient for data transmission requirements and also brings robustness on the performance stability whatever the surrounding organs is. A wireless data transfer link is established between the integrated capsule and external receiver. An in‐vivo measurement is also conducted to validate the system practicability, and besides, the temperature date of a rat is monitored in real time and shown at a display screen.

A Survey of the Thermal Analysis of Implanted Antennas for Wireless Biomedical Devices

“…They are a promising modality for various diagnostic [1,2] and therapeutic [3] clinical applications. Such applications include pacemakers [4], blood-glucose sensors [5], temperature monitoring [6], retinal implants [7], and imaging devices [8]. Examples of available commercial IBDs for different medical purposes are shown in Figure 1.…”

Small Footprint Biocompatible Antenna for Implantable Devices: Design, In-Silico, In-Vitro and Ex-Vivo Testing

“…For biomedical applications, generally, two bands are considered, i.e., MICS (Medical Implant Communication System) band ranging from 402 to 405 MHz and Industrial, Scientific and Medical (ISM) band ranging from 2.4 to 2.48 GHz (Kiourti and Nikita 2012 ; Yoo and Cho 2016 ; Shikha and Sarin 2017 ; Ahlawat 2019 ; Liu et al 2012 ). Some commonly used implantable devices are temperature monitoring devices (Zhang et al 2019 ), functional electrical stimulators (FES) (Guillory and Normann 1999 ), blood glucose monitors (Shults et al 1994 ), cochlear implants (Buchegger et al 2005 ), retinal implants (Gosalia et al 2004 ), pacemakers (Wessels 2002 ), neural recording (Neihart et al 2005 ), etc.…”

Skin and brain implantable inset‐fed antenna at ISM band for wireless biotelemetry applications

“…According to IEEE C95, 1 to 1999 standard it has to be kept lower than 1.6 W/kg for any 1 g tissue of cubic shape (SAR 1g,max ≤ 1.6 W/kg) and for any 10 g tissue of cubic shape it should be kept lower than 2 W/kg (SAR 1g,max ≤ 2 W/kg). [21][22][23] The SAR values are greatly affected by varying antenna geometry, radiated power, frequency of exposure, spacing between antenna and human tissue, and exposure medium. The human body acts as a lossy dielectric medium.…”

“…If body is exposed to the radiation of radio frequencies electromagnetic field above a specific threshold levels of IEEE standards, then it has adverse effects on human body because the power absorbed ( P abs ) by human body is directly proportional to the amount of electric field intensity as shown below in Equation ) where │E│ is the electric field intensity and σ is given as conductivity of the human tissue . According to IEEE C95, 1 to 1999 standard it has to be kept lower than 1.6 W/kg for any 1 g tissue of cubic shape (SAR 1g,max ≤ 1.6 W/kg) and for any 10 g tissue of cubic shape it should be kept lower than 2 W/kg (SAR 1g,max ≤ 2 W/kg) 21‐23 . The SAR values are greatly affected by varying antenna geometry, radiated power, frequency of exposure, spacing between antenna and human tissue, and exposure medium.…”