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

DUARTE, L. C.; FIGUEREDO, F.; RIBEIRO, L. E. B.; CORTÓN, E.; COLTRO, W. K. T.

Foz de Iguazu

Congreso; Reuniao Anual Sociedade Basileira de Química; 2018

Sociedade Basileira de Química

Electrochemical detectionhas been widely explored in microbiology due to its flexibility andcompatibility with microfluidic systems. However, traditional methods ofmanufacturing microfluidic systems require specialized and costlyinstrumentation, as well as laborious steps such as sealing and electrodefabrication procedures. In this way, 3D printing has become an alternativemanufacturing method for analytical microdevices because it allows automated,single-stage and low-cost fabrication of microchannels and electrodes. In thissense, this study presentsan electrochemical approach to quantify E. coli K12 bacteria cells in droplets by means of a C4D system. The microdevice wasfabricated with the aid of a 3D printer, having a T-junction configuration, containing integrated electrodes of PLAdoped with carbon nanotubes, while the microchannels were manufactured with ABSthermoplastic filaments. It was found that the conductivity signal decreasessince bacteria cells affectthe conductivity of the droplet. A linear relationship was found betweenconductivity variation and log10(CFU droplet-1) in arange between 86.5 and 8650 CFU droplet-1 with a LOD of 64.42 CFUdroplet-1. This device was able to evaluate, in real time, bacterial cells number insidedroplets, showing to be a promising assistant to droplet based analyticalbioassays for antibiograms and toxicity tests among others.