Wang Ziheng, Jia Erwen, Sun Zheng, Zhang Ping, Chen Yihao, Feng Xue
IEEE Trans Biomed Eng. 2025 May;72(5):1585-1595. doi: 10.1109/TBME.2024.3513333. Epub 2025 Apr 22.
Hemodynamic pressure (HP) monitoring is critical for managing cardiovascular diseases. Clinical Doppler echocardiography and invasive catheter monitoring cannot realize remote continuous monitoring in daily life. Current implantable wireless equipment depends on custom chips or indirect sensing, presenting challenges in cost-effective and precise applications. Here, we present systematic design strategies for implantable, wireless, and battery-free capsule-like HP monitoring under near and middle-distance circumstances.
The systems were composed of completely non-customized devices, with extremely compact volumes (<0.4 cm). Near-distance monitoring utilized Near Field Communication with a piezoresistive sensor and foldable circuit designs. Middle-distance monitoring employed dual-winding antennas based on magnetic resonance (∼600 kHz) and Bluetooth. The power feedback circuit was optimized through human model electromagnetic simulations. Validation involved in vitro and in vivo experiments.
Near-distance system achieved 0.35 mmHg omnidirectional pressure accuracy under 5 mm tissue shielding. Middle-distance system attained the longest wireless power transfer distance (7.5 cm) via electromagnetic fields, supporting a capacitive sensor with 0.4 mmHg accuracy. In vitro tests in artificial tissue demonstrated stable data/energy transfer, accommodating axial misalignments up to ±45°. In vivo experiments on the beagle demonstrated real-time, wireless monitoring of left atrial pressure, whose rhythm synchronized with electrocardiograph recordings. The interatrial septum interventional installation was also validated.
The wireless and implantable capsules enable near and middle-distance hemodynamic pressure monitoring, even in dynamic swinging intracardiac situations. and has been validated in animal experiments.
The designs provide a universal method for in vivo fully-implantable pressure monitor development.
血流动力学压力（HP）监测对于心血管疾病的管理至关重要。临床多普勒超声心动图和侵入性导管监测无法在日常生活中实现远程连续监测。目前的可植入无线设备依赖于定制芯片或间接传感，在经济高效且精确的应用中面临挑战。在此，我们提出了在近程和中程情况下用于可植入、无线且无电池的胶囊式HP监测的系统设计策略。
该系统由完全非定制的设备组成，体积极其紧凑（<0.4立方厘米）。近程监测利用与压阻式传感器和可折叠电路设计的近场通信。中程监测采用基于磁共振（约600千赫兹）和蓝牙的双绕组天线。通过人体模型电磁模拟对功率反馈电路进行了优化。验证涉及体外和体内实验。
近程系统在5毫米组织屏蔽下实现了0.35毫米汞柱的全向压力精度。中程系统通过电磁场实现了最长的无线功率传输距离（7.5厘米），支持精度为0.4毫米汞柱的电容式传感器。在人工组织中的体外测试表明数据/能量传输稳定，可适应高达±45°的轴向错位。在比格犬身上进行的体内实验证明了对左心房压力的实时无线监测，其节律与心电图记录同步。房间隔介入安装也得到了验证。
这种无线且可植入的胶囊能够实现近程和中程血流动力学压力监测，即使在心脏内动态摆动的情况下也是如此，并且已在动物实验中得到验证。
这些设计为体内完全可植入压力监测器的开发提供了一种通用方法。
