The serial dilution chip for cytotoxicity and cell differentiation test

This paper proposes two types of serial dilution devices for linear and logarithmic concentration gradient. The designs of serial dilution chips were based on the adjustment of flow rate to obtain desired dilution ratio, so that they are not affected by molecular size, flow rate, and diffusion length. The performance of linear dilution chip was verified by image analysis of diluted tryphane blue solution as well as by cytotoxicity test. The analysis of the color intensity indicated that the tryphane blue solution was diluted in linear scale, which was in good agreement with the theoretical value. The percentage of viable cells linearly increased with the concentration of PFA and the standard deviation was within 0.05%. Also, the experiment of logarithmic dilution chip demonstrated that the concentrations of outlet was logarithmically linear, regardless of the variation of flow rates and was in accordance with that of dilution by manual pipetting.