心脏起搏器超声波体外无线充电技术研究

Ultrasonic in vitro Wireless Charging Technology for Cardiac Pacemaker

目的为了解决现有心脏起搏器锂电池携带电量有限的难题,延长起搏器在体内的使用寿命,本研究采用超声波以无创的方式向心脏起搏器无线充电,通过建立理论模型及实验分析,明确超声波无线充电系统的最优工作规律,使该系统更为安全、高效的为心脏起搏器进行无线充电。方法建立了超声波向心脏起搏器无线充电的理论模型和实验模型,采用聚焦超声换能器体外发射低强度脉冲超声,利用体内置入的1-3型压电复合材料俘能器高效接收超声波并将其机械能转化为电能,并通过整流滤波电路及充电保护电路的硬件处理,为心脏起搏器进行充电。通过对理论模拟及实验分析,找出系统的最优工作参数,明确该系统的最优工作规律。结果理论及实验结果表明,在负载电阻等于俘能器的阻抗时,能量传输效率最高,无线充电系统达到最优功率输出,在此负载匹配条件下,若负载电阻的增加,系统最优工作频率从正谐振频率到反谐振频率偏移,且系统最大输出功率峰值出现在正谐振频率和反谐振频率上,实验研究证实:超声波无线传输距离在2.18~5.10 cm范围内,其能量能够被压电俘能器高效接收,轻易的将LED点亮。结论采用超声波以无创的方式向心脏起搏器无线充电的方法是可行的。该研究结果对实现心脏起搏器进行安全、高效的无线充电具有理论意义和应用价值。

Objective: This research aims to solve the drawback of limited life-time of lithium batteries in cardiac pacemaker by wirelessly and non-invasively recharging the cardiac pacemaker in the body with ultrasound to cardiac pacemaker. On the basis of theoretical model and experimental analysis, the working law was optimized to make the system recharge the cardiac pacemaker safely and efficiently. Methods:In this paper, the feasibilities of wireless charging to the cardiac pacemaker with ultrasound are established on the basis of theoretical model and experimental analysis of established. Specifically, the model adopted the low intensity focused ultrasound transducer to emit ultrasonic pulse, and used the placement of 1-3 piezoelectric composites harvester in vitro to receive and convert ultrasound into electricity. The cardiac pacemaker was recharged with hardware treatment of rectifier filter circuit and charging protection circuit. The optimal system parameters and the optimal work rule are determined by theoretical and experimental analyses of the model. Results:According to the theoretical and experimental results, the energy transfer efficiency is the highest and the wireless charging system achieves optimal power output when the load resistor is equal to the impedance of transducer. With the increase of pure resistive load, the operating frequency varies from the resonance frequency to the anti-resonance frequency. Meanwhile, the output voltage increases with the increase of the load, and the maximum output power peak will be in the resonant and anti-resonant frequency. Our results showed that the LED lights can be lit up within the distance range from 2.18 to 5.10 cm, indicating the feasibility of building piezoelectric harvester to extract ultrasonic vibration energy. Conclusion: Theoretical and experimental studies have shown that the wireless charging with ultrasound is feasible. Our work has theoretical significance and the new system shows application potential for cardiac pacemakers charging in vitro.