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What do we need to know about a robot: Accuracy and Precision

 

An error-free liquid handling robot requires both accuracy and precision. An accurate liquid handling robot allows users to be confident about the amount of volume transferred, thus they can determine the concentration of each solvent in the assay correctly. A precise individual channel of a liquid handling robot can perform liquid handling repeatedly such that the concentration levels in the assay are consistent with minimal variability. 

 

Accuracy and precision are represented by relative inaccuracy (inacc) and coefficient of variation (CV) in numerical means.

How accurate and precise it needs to be: Acceptability Criteria

 

Two sets of criteria are proposed by Stangegaard et al. (2011) for assessing the performance of the automated liquid handling robot: For liquid volume less than or equal to 10 μL, the relative inaccuracy less than ±20% and the coefficient of variation less than 10% are considered acceptable; for liquid volume greater than 10 μL, the relative inaccuracy should be less than ±10% and coefficient of variation less than 10%.

How can we assess the robot:
Volume Verification Methods

 

  1. Gravimetric Method: the weight of the liquid delivered by the robot can be converted into a volume by dividing by the density of the liquid.  

  2. Fluorescence-Based Method: the fluorescence intensity of the dispensed fluorescent solution is proportional to the concentration, which corresponds to the volume of liquid dispensed into each well.

  3. Dual-Dye Absorbance-Based Method: according to the Beer-Lambert law, the liquid depth of a dye solution can be estimated by measuring absorbance of the dyes. With the pathlength, we can calculate the liquid volume transfer by geometrical analysis.

THEORY

 

If I have seen further it is by standing on the shoulders of giants. ----- By Ser Issac Newton

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