Horizontal Clinometer Based on a Movable Bubble in the Arc-Shaped Quantum Dots Liquid Cavity

In this paper, we proposed an ultracompact horizontal clinometer based on a movable bubble in the arc-shaped quantum dots (QDs) liquid cavity. The bubble which can move and rest at the arc-shaped inner wall of the liquid cavity enables the structure to be used for sensing of the tilt angle. The experimental results show that the sensor reveals the good response with the quadratic fitting between fluorescence intensities and tilt angles because the bubble blocks the excitation light in two ways, is further verified by theoretical analysis. And the sensor can distinguish the tilt direction via fluorescence intensity. The sensor also shows excellent repeatability and stability. Besides, this kind of horizontal clinometer based on the principle of fluorescence intensity demodulation has the advantages of convenient demodulation, miniaturization and low cost.