Electrical and mechanical performance difference on piezoelectric segmentation in a passive MEMS DC current sensor applicable to two-wire DC appliances

Abstract

As society develops in intelligence, DC is being widely used in all kinds of field in modern life, which means that a sensitive and convenient DC sensor is necessary to monitor it. Compared with other kinds of current sensor, the proposed passive MEMS DC current sensor has several significant features: power-free passive sensing, small size and low cost. In this work, the performance difference of a cantilever-based bending MEMS DC current sensor among three segmentation PZT plates was first experimentally discovered. The distribution difference of X-dir (X-direction) stress along the Y axis is confirmed through FEM analysis. An optimized structure with two slots at the root of the cantilever has been proposed to minimize the difference of average X-dir stress on an area attached to three PZT plates. A nearly linear relationship between the output voltage Voutput and the AC current has been obtained through both theoretical calculation and experimental verification. The sensitivity of the developed MEMS DC current sensor is 40–25 mV A−1 in the current range of 0–400 mA. It is found that there is a good consistency among the calculation, experiment and simulation results.

Passive MEMS DC Electric Current Sensors

“…It is noted from Fig. 15a, b (Wang et al 2017) that, the thicker the PZT plate, the much decrease the values of Q ind and C ind . However, since the decrease of C ind is greater than that of Q ind , an increasing behavior and a maximum point at thickness of 4 μm can be observed for V ind from Fig.…”

“…Then the output voltage, charge, and capacitance of series and parallel can be compared with the connect number of PZT plate, as shown in Fig. 13a, b, c (Wang et al 2017).…”

“…However, since the decrease of C ind is greater than that of Q ind , an increasing behavior and a maximum point at thickness of 4 μm can be observed for V ind from Fig. 15c (Wang et al 2017). Considering the difficulty in device processing, however, a thickness of around 2 μm is thus selected for the present study.…”

“…On the other hand, if the thickness goes to be thicker than the elastic layer, the neutral axis will exist in PZT thin film and cause to cancel the polarization matching. It is thus necessary to keep a thickness balance, usually from 1 μm~10 μm, between PZT thin film and the elastic layer of silicon (Wang et al 2017). ä Fig.…”

“…In the related works (Isagawa et al 2011a, b;Wang et al 2012aWang et al , b, 2013aYang et al 2017), a cantilever-based DC current sensor with or without oscillating pumping was proposed, fabricated, and verified for direct measurements of both the "steady-state" current and the "rise-fall" current switching in one-wire or two-wire electrical appliance cord. In the case with oscillating pumping, it was found that the relative change in the maximum value of the output voltage is approximately proportional to the applied DC current.…”