A continuously recording, impedimetric thermal liquid flow sensor fabricated on a Parylene C thin film substrate is presented for the first time. The sensing concept, inspired by hot-film anemometry, includes an additional upstream unheated reference electrode pair which enabled attenuation of environmental drift in impedance by more than $5\times $ . This sensor design and transduction approach was motivated by the need for an alternative to traditional hot-film anemometers for in vivo applications. An analytical model was developed to describe the axial fluid temperature surrounding the impedimetric sensor and its effect on solution conductivity. The impact of heater power was modeled and matched with experimental data; similar analysis was conducted for other parameters including channel height, ambient temperature, and electrolyte concentration. The sensor achieved a $2\sigma $ resolution of $17~\mu \text{L}$ /min over the range 43–200 $\mu \text{L}$ /min. The models and fabricated device significantly expand our understanding of thermal impedimetric flow sensing. [2020-0357]

中文翻译：

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连续、阻抗式聚对二甲苯流量传感器

首次提出了在 Parylene C 薄膜基板上制造的连续记录、阻抗式热液体流量传感器。受热膜风速测量法启发的传感概念包括一个额外的上游未加热参考电极对，可将阻抗中的环境漂移衰减超过 $5\times $ . 这种传感器设计和转换方法的动机是需要替代传统的热膜风速计体内应用程序。开发了一个分析模型来描述阻抗传感器周围的轴向流体温度及其对溶液电导率的影响。对加热器功率的影响进行建模并与实验数据相匹配；对其他参数进行了类似的分析，包括通道高度、环境温度和电解质浓度。该传感器实现了 $2\西格玛$ 分辨率 $17~\mu \text{L}$ /min 范围 43–200 $\mu \text{L}$ /分钟。这些模型和制造的设备极大地扩展了我们对热阻流传感的理解。[2020-0357]