Research On Implanted Antenna For Medical Telemetry System

Implantable wireless medical device is a new diagnosis and treatment mode in the history of biomedical field.It is produced with the rapid development of microelectronics technology,wireless communication technology and biomedical technology.Because of getting rid of the limitation of space and time,the medical cost and medical time are reduced,which makes the market demand of implantable wireless medical equipment in personal health care is very strong.As the carrier of wireless communication system,implantable antenna is one of the key devices in wireless medical equipment.Therefore,the development of implantable antenna with high performance has very important practical value for the development of wireless medical industry in the future.Based on the current design of implantable antenna,combined with the requirements of miniaturization,broadband,multi-band,security and biological compatibility,this thesis studies and designs the implantable antenna for the purpose of further reducing the antenna size,improving the antenna stability,and realizing the high-speed data transmission of the antenna.The main contents and contributions are as follows:(1)Research on the miniaturization and broadband of the dual-band implantable antennaA dual-band implantable PIFA antenna with broadband characteristics is proposed.A new resonant frequency can be excited by loading an open-slot between the feed point and the short-circuit pin of the Planar Inverted-F Antenna(PIFA)ground,and then the broadband characteristics of PIFA in Medical Implant Communication Services(MICS)band can be realized by combining the adjacent resonant frequencies.At the same time,due to the extension of the current path on the ground,the resonant frequency is reduced and the antenna is miniaturized.The problem that the implantable antenna is sensitive to the working environment due to narrow bandwidth is solved.The results show that the final size of the dual-band implantable antenna based on the PIFA structure is only 49.5 mm~3,and the test bandwidths of the ISM band are 6.9%and 13.9%respectively in the skin gel model and pork tissue,and the test bandwidths of MICS frequency band are 38%and 50.7%respectively in skin gel model and pork tissue.The antenna achieves good working performance.(2)Research on broadband of the capsule antennaA capsule IFA antenna with enhanced bandwidth is proposed.By loading an open-slot on the IFA to extend the current path on the ground plane,making it comparable to the operating wavelength of the antenna,effectively improving the impedance matching of the IFA.When the open-slot is between the feed point and the short-circuit pin,a new resonance frequency point is introduced,and then adjacent resonance frequency points are combined to form a broadband technology,which realizes the broadband characteristics of IFA.The problem of frequency shift of capsule antenna is solved because it needs to work in the digestive tract with different dielectric properties.The experimental results show that the simulation bandwidth of the capsule antenna based on the meandering"F"structure reached 100%in the ISM band with the central frequency of433 MHz,and the measurement bandwidth in fresh pork tissue also reaches 70.2%.Compared with the previous literature,the proposed antenna has good stability,and the gain is relatively satisfactory compared to most published capsule antennas.In addition,according to the selection of biocompatible materials for implantable antenna,a reference method with less impact on antenna performance is proposed.(3)Research on ultra-wideband(UWB)capsule antenna for high-speed data transmissionA UWB capsule antenna based on simple symmetrical double loop structure is proposed.The impedance bandwidth of the antenna is effectively broadened by adding the feeding patch to the center of the feeding loop and changing the feeding direction.Then by introducing an LC load(ie short-circuit patch)to the center of the short-circuit loop and connecting it with the short-circuit loop with a high-impedance line,a new resonance frequency is excited to further broaden the low-frequency bandwidth,and the UWB performance of the capsule loop antenna is realized.It provides a guarantee for high-resolution image datas of the capsule antenna and its high-speed transmission requirements.The experimental results show that the capsule antenna based on a symmetrical double-loop structure has a measurement bandwidth of 124%in the ISM band with a center frequency of 2.45 GHz,and the gain peak value also reaches-12.6 d Bi.Compared with the previous literature,the bandwidth and gain of this proposed antenna are obviously better than other inner-wall capsule antennas,and it is very suitable for wireless endoscope system for high-speed data transmission.