Hacohen Yaneev, Majerus Steve J A
Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, OH 44106 USA.
Advanced Platform Technology Center, VA Northeast Ohio Healthcare System, Cleveland, OH 44106 USA.
IEEE Sens J. 2023 Sep 1;23(17):19044-19051. doi: 10.1109/jsen.2023.3291172.
This work demonstrates a batteryless, implantable blood-flow sensor with radio frequency identification (RFID) readout. This flexible sensor system was developed specifically for surgical implantation around a blood vessel, without contacting blood to reduce platelet deposition, clotting, and other complications with blood-contacting sensors. A flexible sensor and circuit architecture was adopted to enable a cuff-like form factor for surgical implantation around an artery, vein, or graft without piercing or cutting the vessel. This required the development of a flexible RFID data/power antenna using a split-double helix antenna (DHA), which could be opened and closed, unlike a solenoidal or flat spiral antenna. DHAs with diameter of 3-10 mm were fabricated and characterized on the bench, showing a typical coupling coefficient of 0.007 when placed 5 cm from a reader. Prototype implantable DHA systems were developed to wrap around vessels of 3-8 mm. A flexible pulsation sensor (FPS) was developed from a piezoresistive carbon black-polydimethylsiloxane (PDMS) nanocomposite, which enabled the measurement of vascular distension caused by blood flow. A commercial RFID chip enabled sensor readout to an external transceiver in real time with a sample rate of 12 Hz when immersed in saline test media. Validation experiments on a vascular phantom with simulated stenosis demonstrated a blood-flow rate monitoring from 200 to 400 mL/min with the capacity to distinguish flow changes as low as 10 mL/min.
这项工作展示了一种具有射频识别（RFID）读出功能的无电池植入式血流传感器。这种灵活的传感器系统是专门为在血管周围进行外科植入而开发的，不与血液接触，以减少血小板沉积、凝血以及与血液接触传感器相关的其他并发症。采用了灵活的传感器和电路架构，以实现袖带式外形，便于在动脉、静脉或移植物周围进行外科植入，而无需刺穿或切割血管。这需要开发一种使用分裂双螺旋天线（DHA）的灵活RFID数据/功率天线，与螺线管天线或扁平螺旋天线不同，它可以打开和关闭。制作了直径为3 - 10毫米的DHA并在实验台上进行了表征，当放置在距离读取器5厘米处时，其典型耦合系数为0.007。开发了原型植入式DHA系统，用于包裹3 - 8毫米的血管。由压阻式炭黑 - 聚二甲基硅氧烷（PDMS）纳米复合材料开发出一种灵活的脉动传感器（FPS），它能够测量由血流引起的血管扩张。一个商用RFID芯片能够在浸入盐水测试介质时以12赫兹的采样率将传感器读数实时传输到外部收发器。在具有模拟狭窄的血管模型上进行验证实验，结果表明能够监测200至400毫升/分钟的血流速率，并且能够区分低至10毫升/分钟的血流变化。
