Researches On Implantable Antennasfor Biomedical Secices

With the development of biological field,more and more people take interest in wireless medical implantable devices.Painless,real-time,high efficiency has become basic performance of those devices that researchers pursue.Implantable devices can transmit in-body physical information to outer receivers accurately.A complete transmission system is necessary for reliable communication,therefore,research on implantable antennas,internal systems and communication link cannot be ignored.Based on the design of antenna,this paper innovatively proposes several kinds of biomedical antennas,self-phase technology for high-efficiency transmission and temperature monitoring capsule system.The main work contents are as following:(1)A wideband circularly polarized implantable antenna tested in a mixture solution working at 915MHz is presented.Miniaturization is realized by cutting slots and shorting pin,while angle cutting and parameters adjusting promote circular polarization(CP).Besides,a stacked dipole antenna based on conjugate matching technology is proposed.By designing antenna impedance conjugate with chip impedance,it paves way for the miniaturization of the whole capsule system(2)A wireless transmission system based on self-phase technology greatly improving transfer efficiency is proposed.Firstly,an internal coil rectenna is used as transmitter,then making conjugate calculation of the phase received by external slot antenna unit is necessary Secondly,a feeding network is designed.Lastly,outer antenna array is taken for transmitter The experiment demonstrates that the field density around implantable antenna by self-phase feeding is stronger than by in-phase feeding.Therefore,in this way,the optimal path can be automatically established for focusing the transmission energy(3)The capsule system with a dimension of 11mm(diameter)×16mm(length)is proposed for temperature monitoring.In this paper,the wireless data transfer link is established,and an in-vivo measurement is conducted to validate the system practicability.The body temperature of the rate is shown at a display screen.Through practical testing,we believe that the capsule system will lay a good foundation for future medical applications.In short,from antenna design to optimized communication link and integrated system design,this paper innovatively proposes several works for good application prospect.