The study of liquid control level detection system applying to micro biological samples

The liquid level detection of micro-biological samples is the key technology aiming to achieve automatic operation with high dependability and high accuracy. Based on the principle of capacitance detection, we propose a novel integrated detector whose core structure is a coaxial cylinder. The mathematic model of liquid level detector is built. The structure is optimized and the key parameters are also calculated. The effect of capillary phenomenon is discussed. The detection system consists of the capacitance detection circuit and signal processing unit. The experiment data show that the detecting respond time to ethanol sample level is 200ms. The developed detector meets the system demand.