Contactless conductivity detection of bacteria in droplets using 3D printed microfluidic device

RIBEIRO, LUIZ E.B.; DUARTE, LUCAS C.; CORTÓN, EDUARDO; FIGUEREDO, F.; COLTRO, WENDELL K.T.

Foz do Iguazu

Congreso; Reuniao Anual Sociedade Basileira de Química; 2018

Sociedade Basileira de Química

For the detection of cells inside droplets, fluorescent labelling is a technology accessible and well established in conventional methods of microbiology that have been widely used1,2. Fluorescent markers, when added to the sample as a reagent can be used for a wide range of microorganisms, but some relevant problems associated to them are high cost, disposal problems (most of them are toxic) and instability (photo bleaching). This study presents an electrochemical and label free approach to quantify E. coli K12 cells in droplets by means of a C4D system. The microdevice was fabricated with a 3D printer, containing integrated electrodes of PLA doped with CNT3 (Figure 1). It was found that the conductivity signal decreases since bacteria cells change the conductivity of the droplet. A linear relationship was found between conductivity variation and log10(CFU droplet-1) in a range between 86.5-8650 CFU droplet-1 with a LOD of 64.42 CFU droplet-1.