Automated carousel-based electrochemical sensing toward microbiological and oncological settings

The integration of automation and electrochemical sensing is emerging as an important strategy to accelerate bioanalytical workflows, improve reproducibility, and reduce operator exposure to hazardous biological samples. Self-driving laboratories and automated analytical systems have attracted increasing attention in chemical and biomedical sciences due to their potential for scalable and high-throughput experimentation. However, most automated electrochemical platforms still rely on expensive robotic infrastructure and are often inaccessible for laboratories with limited resources. In addition, applications involving pathogenic microorganisms and 3D cell cultures require safer and more controlled analytical environments. Therefore, there remains a need for portable, low-cost, and semi-autonomous electrochemical systems capable of operating in microbiological and oncological settings.

Herein, we report the development of the Carousel ElectroLab System (CELS), a portable and low-cost automated electrochemical platform integrating 3D-printed electrodes, Arduino-controlled carousel automation, and wireless communication with a miniaturized potentiostat. The system consists of eight fully 3D-printed electrochemical cells sequentially addressed for hands-free electrochemical measurements. Blue-laser treatment of the electrodes increased surface roughness and electrical conductivity, resulting in improved electrochemical performance and reproducibility (RSD <5%). As a proof-of-concept, the platform was applied in microbiological and oncological analyses. For microbiological applications, selective detection of Pseudomonas aeruginosa was achieved through electrochemical monitoring of pyocyanin (PYO), reaching a detection limit of 0.89 CFU mL^-1 in King's A medium, with no significant response observed for other bacterial strains. In oncological studies, the system monitored doxorubicin-induced cytotoxicity in MCF-7 tumoroids by quantifying lactate dehydrogenase activity through NADH electrooxidation, enabling correlation between electrochemical signal and tumor cell death in 3D models.

This work introduces a portable carousel-based electrochemical platform combining 3D printing, low-cost automation, and wireless electrochemical sensing for bioanalytical applications in controlled environments. The proposed CELS device represents a scalable and open-source alternative to conventional automated systems, enabling safer and reproducible analyses of pathogenic microorganisms and 3D tumor models. The modular architecture also provides a foundation for future integration of robotic fluidics and AI-assisted self-driving laboratory functionalities.