[The development of techniques for liquid level detection in auto clinical laboratory analyzers]

Liquid level detection (LLD) is necessary for eliminating carry-over of needle's outside by limiting the depth the needle probes into liquid in auto clinical laboratory analyzers. This paper listed various demands of liquid-handling system under different situations; reviewed various LLD techniques, such as capacitive, air pressure, mechanical vibration, ultrasound, light reflection, CCD imaging etc.; briefly introduced the working principles, features, and limitation of the LLDs; and recapitulated the characteristics of contact and non-contact LLDs. Lastly, the next generation technique of LLD is prospected.