No. It is not necessary to clean and dry the measuring cell between single measurements. Sample residues in the measuring cell will be fully replaced by the subsequent sample.
EasyDens comes with a 10 mL syringe. We recommend using a syringe of this size because 10 mL are sufficient to fully replace the previous sample and fill the measuring cell with the new sample. Even if the measuring cell has been filled with water, 10 mL of the new sample are sufficient to prevent a dilution of your sample.
So you do not risk producing wrong measuring results due to the mixing of the current sample with the previous one or with water in the measuring cell.