Pipette basic principle:

The micropipette has a liquid absorption range of 1-1000~1, which is suitable for use in clinical routine chemical laboratories. The micro-sampler has been developed to date, not only for more accurate sample loading, but also for a variety of varieties, such as micro-dispensers, multi-channel micro-samplers, etc. The physics of loading is as follows:

1 using air cushion (also known as piston stroke) loading;

2 Use a piston without air cushion to positively load the sample.

The above two different principles of micropipettes have different specific application ranges.

First, the air pad loader

The piston stroke (air cushion) applicator can be easily used for the loading of fixed or adjustable volume liquids with a loading volume ranging from less than 1 ul to 10 ml. The air cushion in the applicator separates the liquid sample sucked into the plastic tip from the piston in the applicator, and the air pad moves through the spring-like motion of the applicator piston, thereby driving the tip The increase in the height of the liquid, dead volume and pipetting tips determines the degree of expansion of the air cushion during loading.

Therefore, the volume of piston movement must be about 2% to 4% larger than the volume desired to be absorbed. The effects of temperature, air pressure and air humidity must be reduced by structural improvements to the air pad applicator, so that under normal conditions Does not affect the accuracy of the sample.

The disposable tip is an important part of the sample loading system. Its shape, material properties and the degree of fit with the sampler have a great influence on the accuracy of the sample.

Second, the piston is moving the sampler

The applicator and dispenser with the principle of positive piston movement are different from the physical factors affected by the air cushion applicator.

Therefore, in the case where the air cushion applicator is difficult to apply, the piston moving sample applicator can be applied, such as a liquid having a high vapor pressure, a high viscosity, and a liquid having a density of more than 2.0 g/cm 3 ; In the chain reaction (PCR) measurement, in order to prevent the generation of aerosol, it is preferable to use a piston positive moving sampler.

The tip of the piston moving sample applicator differs from the air pad applicator tip in that it contains a piston that can be coupled to the plunger of the applicator, which is typically produced by the production piston moving the applicator. Manufacturers supporting production, can not use the usual tips or tips from different manufacturers.

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