Department of Electrical Engineering, The University of Texas at Arlington, Arlington, TX 76010, USA.
IEEE Trans Biomed Eng. 2012 Nov;59(11):3131-9. doi: 10.1109/TBME.2012.2214773. Epub 2012 Aug 22.
In this study, a device for gastroesophageal reflux disease (GERD) monitoring has been prototyped. The system consists of an implantable, batteryless and wireless transponder with integrated impedance and pH sensors; and a wearable, external reader that wirelessly powers up the transponder and interprets the transponded radio-frequency signals. The transponder implant with the total size of 0.4 cm × 0.8 cm × 3.8 cm harvests radio frequency energy to operate dual-sensor and load-modulation circuitry. The external reader can store the data in a memory card and/or send it to a base station wirelessly, which is optional in the case of multiple-patient monitoring in a hospital or conducting large-scale freely behaving animal experiments. Tests were carried out to verify the signal transduction reliability in different situations for antenna locations and orientation. In vitro, experiments were conducted in a mannequin model by positioning the sensor capsule inside the wall of a tube mimicking the esophagus. Different liquids with known pH values were flushed through the tube creating reflux episodes and wireless signals were recorded. Live pigs under anesthesia were used for the animal models with the transponder implant attached on the esophageal wall. The reflux episodes were created while the sensor data were recorded wirelessly. The data were compared with those recorded independently by a clinically used wireless pH sensor capsule placed next to our implant transponder. The results showed that our transponder detected every episode in both acid and nonacid nature, while the commercial pH sensor missed events that had similar, repeated pH values, and failed to detect pH values higher than 10. Our batteryless transponder does not require a battery thus allowing longer diagnosis and prognosis periods to monitor drug efficacy, as well as providing accurate assessment of GERD symptoms.
在这项研究中，我们开发了一种用于胃食管反流病（GERD）监测的设备。该系统由一个植入式、无电池和无线应答器组成，其中集成了阻抗和 pH 传感器；以及一个可穿戴的外部读取器，它可以为应答器无线供电并解释转发的射频信号。应答器植入体的总尺寸为 0.4 厘米×0.8 厘米×3.8 厘米，它可以采集射频能量来运行双传感器和负载调制电路。外部读取器可以将数据存储在内存卡中，也可以将其无线发送到基站，在医院中对多个患者进行监测或进行大规模自由行为动物实验时，可以选择这种方式。我们进行了测试，以验证在不同的天线位置和方向情况下信号传输的可靠性。在体外，我们在一个模仿食管的管状人造模型中进行了传感器胶囊的位置实验，通过该模型来验证传感器的位置和方向。我们用不同 pH 值已知的液体通过管道来模拟反流事件，并记录无线信号。在麻醉状态下的活体猪被用于动物模型实验，应答器被植入在猪的食管壁上。在无线记录传感器数据的同时，我们创建了反流事件。我们将记录的数据与临床使用的无线 pH 传感器胶囊独立记录的数据进行了比较，该胶囊被放置在我们的植入式应答器旁边。结果表明，我们的应答器可以检测到所有酸性和非酸性反流事件，而商业 pH 传感器会错过具有相似、重复 pH 值的事件，并且无法检测 pH 值高于 10 的事件。我们的无电池应答器不需要电池，因此可以延长诊断和预后监测药物疗效的时间，并对 GERD 症状进行准确评估。
