In the contact type capacitive liquid level sensors, when an electrode with the insulating film is immersed in polar/ionic medium, it shows constant phase behavior at metal–insulator interface due to the formation of the double layer. This double layer effect is frequently modeled by a pure capacitor but its capacitance value depends on signal frequency. Therefore, when such a sensor is excited by sinusoidal ac, the conducting liquid level measurement suffers from the error due to the fluctuation of input signal frequency. This is because the excitation frequency applied from the source meter may fluctuate. This important issue is rarely discussed for the capacitive level sensors. In addition, the design and realization of the capacitive level sensor require special arrangements for the minimization of parasitic earth capacitance, offset capacitance, and the capacitances due to leads and contact electrodes. In this paper, we propose a novel constant phase impedance sensor for the measurement of conducting liquid levels in the range of 0–4 cm for the first time. The phase angle of the device changes due to a change in the liquid level. Two important characteristics parameters of the sensor are the constant phase angle for a certain frequency range and the fractional order in the range of 0–1. Some important features of the sensor are significant sensitivity (2.1${}^{\circ }$/cm, probe 1) due to small change in conducting liquid, stable output due to fluctuation of input frequency, and the fabrication of the sensor is very simple and inexpensive. The device is finally interfaced to a phase detection circuit to convert the phase angle into a voltage signal.

在接触式电容式液位传感器中，当带有绝缘膜的电极浸入极性/离子介质中时，由于双电层的形成，它在金属-绝缘体界面表现出恒定的相行为。这种双层效应通常由纯电容器建模，但其电容值取决于信号频率。因此，当这种传感器被正弦交流激励时，由于输入信号频率的波动，进行的液位测量会产生误差。这是因为从源表施加的激励频率可能会波动。对于电容式液位传感器，很少讨论这个重要问题。此外，电容式液位传感器的设计和实现需要特殊安排以最小化寄生接地电容，偏移电容，以及由引线和接触电极引起的电容。在本文中，我们首次提出了一种新型恒相阻抗传感器，用于测量 0-4 cm 范围内的导电液位。装置的相位角因液位变化而变化。传感器的两个重要特性参数是一定频率范围内的恒定相位角和 0-1 范围内的分数阶数。传感器的一些重要特性是显着的灵敏度 (2.1 传感器的两个重要特性参数是一定频率范围内的恒定相位角和 0-1 范围内的分数阶数。传感器的一些重要特性是显着的灵敏度 (2.1 传感器的两个重要特性参数是一定频率范围内的恒定相位角和 0-1 范围内的分数阶数。传感器的一些重要特性是显着的灵敏度 (2.1${}^{\circ }$/cm, 探针 1) 由于导电液体的变化很小，由于输入频率的波动而输出稳定，并且传感器的制造非常简单且成本低廉。该器件最终连接到相位检测电路，将相位角转换为电压信号。