Research On Miniaturized Broadband Implantable Antenna For Biomedical Electronics

In recent years,implantable medical devic es are becoming more and more widely used.Implantable antennas as their important components have also received attention.Implantable antennas mainly serve micro and small systems,especially biomedical electronic devices.The implantable antenna can pro vide functions such as wireless communication and data transmission,remote power supply,and remote-control telemetry.The presence or absence of an antenna and its performance directly affect the functionality,convenience,security and reliability of th e system.With the rapid development of information technology today,the research and development of implantable antennas are of great signific ance and value to the medical electronics industry.In this context,this paper designs a variety of implantable antennas for different functional requirements and different application scenarios,and studies the miniaturization,ultra-wideband,and dual-band characteristics of implantable antennas.At the same time,considering the special working environment of implantable antennas,capsule conformal antennas and planar structure antennas are studied based on different working environments.Furthermore,the influence of the radiated power of the implantable antenna on human safety is analyzed.Biomedical electronic implantable antennas have further room for improvement in terms of form,size,and indicators.In view of the large size of implantable antennas,the urgent need to enhance performance,and the lack of a single form,antennas with small size and excellent performance are designed.The focus is on how to meet the challenge of miniaturization and excellent performance at the same time.The paper focuses on the design of three biomedical electronic broadband miniaturized implantable antennas for different application scenarios.The main work is as follows:1.A design scheme of implantable antenna combining coplanar waveguide feeding technology and dual-frequency miniaturization is proposed.A tiny and compact coplanar waveguide-fed dual-band implantable antenna for biomedicine is designed,with dual-band operating characteristics.The antenna works in the Industrial,Scientific and Medical(ISM)low frequency band(433～434.8 MHz)and the Wireless Medical Telemetry Service(WMTS)frequency band(1.395～1.40 GHz),and the size is only 10 mm×10 mm×1.27 mm.The designed antenna adopts a coplanar waveguide feeding structure,which is easy to integrate with other structures,and adopts a high dielectric constant d ielectric substrate and a folded meander-like dipole structure to effectively reduce the size of the antenna.On the premise of meeting the SAR(Specific Absorption Rate)standard,a U-shaped ground plane is used to obtain a higher gain.The highest gain a t the resonant frequency in the two bands reaches-32.23 dBi and-20.63 dBi,respectively.Finally,through the analysis,it is concluded that the simulation results are basically consistent with the test data,and the agreement is good.2.A novel structural design method for loading UGB and SRR is proposed,and an ultra-wideband flexible implantable antenna for wireless capsule endoscopy system is designed,which realizes ultra-wideband and structural conformality of the antenna,and can support the human body Internal and external communications,fully covering the industrial,scientific,medical frequency bands(ISM,2.4-2.48 GHz)and Wireless Medical Telemetry Service(WMTS,1.395-1.4 GHz)frequency bands.The antenna volume is only 18mm~3.The use of antennas conformal to the electronic capsule endoscopy system further reduces the size.The antenna is based on a coplanar waveguide-fed compact planar slotted antenna,and the U-shaped GroundBranch(UGB)and loaded split ring resonator(SRR)structure are introduced to further improve the antenna performance.Under the premise of meeting the radiation safety requirements,the ultra-wideband operation is realized while ensuring the miniaturization of the antenna.Finally,the antenna was fabricated and teste d according to the optimized structure.The test results basically meet the design requirements and are basically consistent with the simulation results.3.A design scheme combining slotted grounding structure and folded meandering radiation structure is proposed,and a tiny and compact implantable antenna for wireless cardiac pacemaker system is designed,with ultra-small structure and excellent performance characteristics.The antenna operates in the ISM band(2.4-2.48 GHz).The use of high dielectric co nstant medium and folded helical structure greatly reduces the size of the anten na,with a volume of 4.5 mm~3 and a size of only 3 mm×3 mm×0.5 mm.Through literature research,this design is the smallest structure among the current implantable antennas of the same type.By optimizing and loading a defected slotted structure,the ra diation capability is improved,thereby increasing the antenna gain.It has good impedance matching characteristics in the entire ISM frequency band,its bandwidth reaches 22%,and its peak gain is-24.9 dBi.The antenna is processed and fabricated and tes ted in a microwave anechoic chamber.The measured data is in good agreement with the simulation results.In addition,specific absorption rate(SAR)of the antenna is also evaluated and analyzed to meet the IEEE’s limited requirements for hu man radiation safety.The results show that this antenna is the best choice for wireless biotelemetry communication in the extremely compact space of systems such as wireless cardiac pacemakers.The designed antenna has the advantages of miniaturization,radiation safety,broadband,high gain,and etc.The research results can provide constructive refe rence value for the design of biomedical electronic implantable antenna and its application in different scenarios.