Flow and level sensing by waveform coupled liquid-solid contact-electrification

Flow detection plays important roles in industrial manufacturing and scientific research. In this work, a liquid-solid contact-electrification waveform coupling method is demonstrated. A Venturi-type triboelectric flow sensor (VTTFS) is reported, which mainly consists of a Venturi tube and a U-tube filled with liquid solution. Multiple copper electrodes are evenly distributed on the left-hand tube (LT) and right-hand tube (RT) of the U-tube with a specific phase difference. Therefore, with the flow changing, the liquid in the U-tube appears alternately among the electrodes and electrode gaps of the LT and the RT which constitute two circuits of the VTTFS. Specifically, when the left-hand circuit and right-hand circuit are coupled, the VTTFS can generate a series of sawtooth signals. The features of flow can be demonstrated through counting the pulses induced by the VTTFS and identifying the trends of the pulse signals, and the flow from 95 L/min to 215 L/min is effectively detected on base of the pulse numbers. This work provides a novel waveform coupling method for flow sensing. Besides, it can also be expanded to practical applications of triboelectric nanogenerators to the industrial manufacture, pipeline transportation, and medical health fields.