What is Liquid Level Detection (LLD) and why is it so important?

Not all samples are received with the same volume of liquid in the vessel. Therefore, pipetting from a fixed height can result in over or under aspiration, cross-contamination, or other costly errors which can sacrifice sample integrity or jeopardize results. With simple high-level commands, ZEUS X1 finds the surface of the liquid and positions the tip accordingly. The head then follows the meniscus down during aspiration and up during dispense, holding its precise position below the meniscus to ensure quality and reliable results every time. Some pipette components claim LLD capabilities when all they really provide is the raw capacitance or pressure output, and the integrator is left with the real work, which increases project complexity and often delays development timelines.

Pressure and Capacitive LLD

ZEUS X1 contains both capacitive and pressure liquid level detection (LLD). Capacitive LLD (cLLD) may only be used with conductive liquids and requires conductive tips. The pipetting channel modulates the tip with a high-frequency AC signal. As soon as the tip touches the surface of the liquid, the capacitance of the system changes, which causes a change in the AC signal indicating the liquid level is detected.

Pressure LLD (pLLD) can be used with both conductive and non-conductive liquids. The pipette head moves down slowly. When the tip hits the liquid's surface, the pressure sensor measures a change in pressure indicating the surface has been found.