Smart Sensors Laboratory, Lambe Institute for Translational Research, College of Medicine, Nursing Health Sciences, University of Galway, H91 TK33 Galway, Ireland.
Electrical and Electronic Engineering, University of Galway, H91 TK33 Galway, Ireland.
Sensors (Basel). 2022 Nov 1;22(21):8402. doi: 10.3390/s22218402.
The wireless monitoring of key physiological parameters such as heart rate, respiratory rate, temperature, and pressure can aid in preventive healthcare, early diagnosis, and patient-tailored treatment. In wireless implantable sensors, the distance between the sensor and the reader device is prone to be influenced by the operating frequency, as well as by the medium between the sensor and the reader. This manuscript presents an ex vivo investigation of the wireless linkage between an implantable sensor and an external reader for medical applications. The sensor was designed and fabricated using a cost-effective and accessible fabrication process. The sensor is composed of a circular planar inductor (L) and a circular planar capacitor (C) to form an inductor-capacitor (LC) resonance tank circuit. The reader system comprises a readout coil and data acquisition instrumentation. To investigate the effect of biological medium on wireless linkage, the readout distance between the sensor and the readout coil was examined independently for porcine and ovine tissues. In the bench model, to mimic the bio-environment for the investigation, skin, muscle, and fat tissues were used. The relative magnitude of the reflection coefficient (S11) at the readout coil was used as a metric to benchmark wireless linkage. A readable linkage signal was observed on the readout coil when the sensor was held up to 2.5 cm under layers of skin, muscle, and fat tissue. To increase the remote readout distance of the LC sensor, the effect of the repeater coil was also investigated. The experimental results showed that the magnitude of the reflection coefficient signal was increased 3-3.5 times in the presence of the repeater coil, thereby increasing the signal-to-noise ratio of the detected signal. Therefore, the repeater coil between the sensor and the readout coil allows a larger sensing range for a variety of applications in implanted or sealed fields.
关键生理参数（如心率、呼吸率、体温和压力）的无线监测有助于预防性保健、早期诊断和针对患者的治疗。在无线植入式传感器中，传感器与读取器设备之间的距离容易受到工作频率以及传感器与读取器之间介质的影响。本文对用于医疗应用的植入式传感器与外部读取器之间的无线连接进行了离体研究。该传感器采用具有成本效益且易于获取的制造工艺进行设计和制造。该传感器由圆形平面电感器 (L) 和圆形平面电容器 (C) 组成，形成电感器-电容器 (LC) 谐振槽路。读取器系统由读取线圈和数据采集仪器组成。为了研究生物介质对无线连接的影响，分别检查了传感器和读取线圈之间的读取距离，以研究猪和羊组织的影响。在台式模型中，为了模拟生物环境进行研究，使用了皮肤、肌肉和脂肪组织。读取线圈的反射系数 (S11) 的相对幅度用作基准无线连接的指标。当传感器在皮肤、肌肉和脂肪组织的各层下保持 2.5 厘米时，在读取线圈上观察到可读的连接信号。为了增加 LC 传感器的远程读取距离，还研究了中继线圈的效果。实验结果表明，在存在中继线圈的情况下，反射系数信号的幅度增加了 3-3.5 倍，从而提高了检测信号的信噪比。因此，在传感器和读取器线圈之间使用中继线圈可以为各种植入式或密封式应用提供更大的感应范围。
