Sensor calibration for different microbial cultures cell density. The dependence of absorbance and autofluorescence intensity on inoculum cell density was recorded for different microorganisms. The signals were calculated as mean value of 30 droplets with an average size of 440 nL, using the multi-channel photo-fluorimeter device configuration: absorbance at 470 nm and 405 nm, fluorescence channels: ex. 470/em. 515 nm and ex. 405/em. 425 nm; (A) Absorbance of C. glutamicum; (B) absorbance of C. vulgaris, (C) absorbance of E. coli RV308, (D) absorbance of B. sporothermodurans PL01, (E) autofluorescence of C. glutamicum, (F) autofluorescence of C. vulgaris, (G) autofluorescence of E. coli RV308, (H) autofluorescence of B. sporothermodurans PL01.