| Micro-implantable electronic devices with wireless power transfer(Wireless Power Transfer,WPT)power supply are hot spots and difficulties in the development of modern medical equipment.The application of WPT technology can simplify the surgical implantation process of medical devices,avoiding the need for secondary surgery to replace the internal battery due to the exhaustion of the battery.At the same time,data exchange was required between the internal implant device and external equipment to achieve health monitoring and control,so transcutaneous wireless communication technology had also received much attention.In order to solve the problem of transcutaneous wireless stable power supply of implantable devices in freely moving organisms,a power transmitting coil capable of generating a uniform magnetic field was optimized.Based on the analysis of the axial magnetic field distribution of the planar spiral structure transmitting coil,the coefficient of variation(COV)of the axial magnetic field distribution of the coil was used as the optimization goal,and the genetic algorithm was used to optimize the trace width and trace spacing of the coil.Finally,a planar spiral coil capable of generating a uniformly distributed magnetic field was designed.The simulation and experimental measurement results showed that the axial magnetic field uniformity had been significantly improved after the trace width and trace spacing are optimized.Compared with the planar spiral coils of equal trace width and trace spacing,the axial uniformity of the transmitting coil after the optimized design was improved by 489.2%.For the wireless data transmission of implantable devices,due to the small size of the internal power receiving/data sending coil,the power received by the internal implanting device is very limited,and it is seriously mismatched with the external energy transmitting/data receiving large coil.It is difficult to establish the uplink(in vivo to in vitro)data link.Therefore,a single coil group with the same carrier frequency wireless power and up-link data transmission time-sharing transmission scheme was developed,which used a strong pulse magnetic field(Pulse Magnetic Field,PMF)coupling to send the in vivo sensor data to the external energy transmission/data receiving end.The experimental results showed that the output pulse amplitude of the PMF generating circuit in the body was not less than 28 V under a voltage input of 3V,and when the distance between the receiving and transmitting coils was 20 mm,the amplitude of the induced voltage across the external energy transmission/data receiving coil changed the highest up to 3.0V.Therefore,the proposed method can effectively establish the uplink data link between the deep implant device and the extracorporeal wearable energy transmitting/receiving coil,and can realize the wireless transmission of the same carrier frequency of the single coil group of power and reverse data.Aiming at the requirements of surgical implantation of power receiving coils for tubular organs in vivo,a double-helix tapped coil was designed in this paper.During surgery,the double-helix flexible circuit board with printed sinusoidal wires was wrapped around the target organ and curled to form a three-dimensional resonant coil.Compared with solenoids,the double-helix structure tapped coil could form a strong magnetic field coupling with the planar spiral coil parallel to the body surface after wearing,which was conducive to improving the transcutaneous of power and data wireless transmission. |
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