Real-time Detection of Pathogens in Hydroalcoholic Solutions during Hand Disinfection Process

As we learned from the COVID-19 pandemic, hand hygiene is a crucial barrier for the limitation of infection outbreaks, especially in sensitive areas such as hospitals. Any sensor able to generate early alerts in case of contamination risk is therefore of great interest for public healthcare. Among the different technologies already explored for bacterial identification, impedance spectroscopy is one of the easiest to implement and to integrate inside everyday devices. However, bacterial identification by impedance spectroscopy is generally carried out in an aqueous medium, i.e. conductive solution, and with microelectrodes whose size is adapted to the size of the bacteria. In this paper, we demonstrate that it is possible to perform measurements directly in a hydroalcoholic medium, i.e. non-conductive solution, and with millimeter-scale electrodes, which are less expensive to produce and easier to integrate in any medical device. The results show that when a sample contains bacteria, even at low concentrations, the impedance spectrum of the hydroalcoholic solution is significantly altered. This result is an important proof of concept for the development of hand disinfectant dispensers capable of analyzing hand-washing residues in real-time and of raising alerts when samples contain an unusual quantity of bacteria.