In Vivo Verification of Implantable Antennas Using Rats as Model Animals

Seo

2014

ETRI J

For this study, we designed an implantable rectangular spiral antenna for medical biotelemetry in the Medical Implant Communications Service band (402 MHz to 405 MHz). The designed antenna has a U-shaped loop for impedance matching. The antenna impedance is easily adjusted by controlling the shape and length of the Ushaped loop. Significant design parameters were studied to understand their effects on the antenna performance. To verify the potential of the antenna for the desired applications, we fabricated a prototype and measured its performance in terms of the resonant characteristics and gain radiation patterns of the antenna. In the testing phase, the prototype antenna was embedded in human skin tissue-emulating gel, which was developed to simulate a real operation environment. The measured resonant characteristics show good agreement with the simulations, and the -10 dB frequency band is within the range of 398 MHz to 420 MHz. The antenna exhibits a maximum gain of -22.26 dBi and an antenna efficiency of 0.215%.

Section: Measurement Of Fabricated Antennasupporting

confidence: 61%

Design of Implantable Rectangular Spiral Antenna for Wireless Biotelemetry in the MICS Band

Seo

2014

ETRI J

“…PIFA antennas have been proposed for implantable medical devices [3][4][5][6][7][8][9][10][11][12][13][14][15]. Spiral-type radiators are usually applied to reduce the total antenna size.…”

Section: Methods and Simulation Setupmentioning

confidence: 99%

“…In recent years, much work has been performed on the design and characterization of implantable antennas [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In general, the design of the antennas takes into consideration specific single tissues and they are tested using tissue-equivalent liquids [3][4][5][6][7][8][9][10], mimicking gels [11,12] and animals [13].…”

Section: Introductionmentioning

confidence: 99%

“…In general, the design of the antennas takes into consideration specific single tissues and they are tested using tissue-equivalent liquids [3][4][5][6][7][8][9][10], mimicking gels [11,12] and animals [13]. To date, detuning analysis has been limited to evaluating the resonance response of the proposed antennas implanted in fluids that simulate single biological tissues [14,15].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Detuning Study of Implantable Antennas Inside the Human Body

Vidal¹,

Curto²,

López-Villegas³

et al. 2012

PIER

Abstract-This study quantifies the detuning and impedance mismatch of antennas implanted inside the human body. Maximum frequency shifts caused by variations in the electrical properties of body tissues and different anatomical distributions were derived. The results are relevant to the design of implantable antennas. They indicate the bandwidth enhancement and initial tuning necessary for correct functioning. The study was carried out using electromagnetic modeling based on the finite-difference time-domain method and highresolution anatomical models. Four anatomical computer models of two adults and two children were used. The implanted antennas operated in the Medical Implant Communication Service band. The most important detuning and impedance mismatch was found for subcutaneous locations and in areas where a layer of fat tissue was present. The maximum frequency shift towards higher frequencies was 70 MHz. The frequency shift did not occur symmetrically around 403 MHz, but was shifted towards higher frequencies.

“…At this stage, in vivo measurements for the purpose of simulation data validation are not feasible due to strict animal ethic regulations. The alternatives to the in vivo measurement include in vitro measurement using tissue mimicking fluid [9,12,13] or gel [14], measurement using minced pork [15,16], or in vivo measurement using rats [17].…”

Section: Introductionmentioning

confidence: 99%

Hermetic Implantable Antenna Inside Vitreous Humor Simulating Fluid

Permana¹,

Fang²,

Rowe³

2013

PIER

Abstract-Retinal prosthesis system is currently being developed in various places around the world. This system involved data transfer between an implanted antenna inside an eyeball and an external camera that is located just in front of the eyeball. While there are plenty of publications about the stimulating electrodes or the processing unit of the system itself, very limited amount has been published regarding the wireless communication link between the two antennas despite the fact that the electromagnetic wave will propagate through a complex medium in the form of Vitreous Humor. This paper will discuss about the constraints associated with implanting an antenna into an eyeball. An antenna design and simulation was performed with the aid of High Frequency Structure Simulator (HFSS) and its Finite Element Method (FEM) mathematical solver in the operating frequency of 402-405 MHz. The antenna, which was a 4 layer microstrip antenna, was positioned at the centre of a spherical model filled with homogeneous Vitreous Humor material. Antenna performances that include return loss, bandwidth, gain, radiation pattern, and SAR value are analysed and compared against those of other implantable antennas operating in Medical Implant Communication Service (MICS) band. Free space and simulating fluid measurements were also conducted on the fabricated antenna to validate the simulation results. It was concluded that the fabricated antenna was able to produce the similar performance to the simulation results and hence at the same level as the other antennas operating in material with lower dielectric constants and conductivities.