Modeling and Characterization of Scaling Factor of Flexible Spiral Coils for Wirelessly Powered Wearable Sensors
Modeling and Characterization of Scaling Factor of Flexible Spiral Coils for Wirelessly Powered Wearable Sensors
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DOI：
10.3390/s20082282
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发表时间：
2020-04-01
期刊：
影响因子：
3.9
通讯作者：
Mahbub, Ifana
中科院分区：
文献类型：
--
作者：
Biswas, Dipon K.;Sinclair, Melissa;Mahbub, Ifana
可穿戴传感器因其紧凑的尺寸和便携性而成为医疗保健监测领域的热门话题。然而，为可穿戴传感器提供持续健康监测应用的电源是一个巨大的挑战。由于电池体积庞大且需要频繁充电，因此将无线功率传输 (WPT) 模块集成到可穿戴和植入式传感器中是一种流行的替代方案。灵活的传感器受益于无线供电，因为它不仅扩大了个人的运动范围，而且还减少了整体尺寸和能源需求。本文介绍了用于 WPT 系统的具有不同比例因子的柔性方形螺旋线圈的设计、建模和实验表征。针对柔性平面线圈的情况，对线圈比例因子对电感、电容、电阻和品质因数（Q 因子）的影响进行了建模、仿真和实验验证。所提出的分析模型有助于估计线圈参数，而无需使用耗时的有限元法（FEM）模拟。分析模型以比例因子的形式呈现，以找到具有最大 Q 因子的最佳优化线圈尺寸。本文还介绍了皮肤与柔性线圈接触对功率传输效率（PTE）的影响，以验证其作为可穿戴传感器的适用性。 405 MHz 的测量结果表明，当与皮肤接触时，20 mmx 20 mm 接收器 (RX) 线圈在发射器 (TX) 和 RX 线圈之间的距离为 10 mm 时，通过空气介质的效率达到 42%。
Wearable sensors are a topic of interest in medical healthcare monitoring due to their compact size and portability. However, providing power to the wearable sensors for continuous health monitoring applications is a great challenge. As the batteries are bulky and require frequent charging, the integration of the wireless power transfer (WPT) module into wearable and implantable sensors is a popular alternative. The flexible sensors benefit by being wirelessly powered, as it not only expands an individual's range of motion, but also reduces the overall size and the energy needs. This paper presents the design, modeling, and experimental characterization of flexible square-shaped spiral coils with different scaling factors for WPT systems. The effects of coil scaling factor on inductance, capacitance, resistance, and the quality factor (Q-factor) are modeled, simulated, and experimentally validated for the case of flexible planar coils. The proposed analytical modeling is helpful to estimate the coil parameters without using the time-consuming Finite Element Method (FEM) simulation. The analytical modeling is presented in terms of the scaling factor to find the best-optimized coil dimensions with the maximum Q-factor. This paper also presents the effect of skin contact with the flexible coil in terms of the power transfer efficiency (PTE) to validate the suitability as a wearable sensor. The measurement results at 405 MHz show that when in contact with the skin, the 20 mmx 20 mm receiver (RX) coil achieves a 42% efficiency through the air media for a 10 mm distance between the transmitter (TX) and RX coils.