Flexible impedance sensor for wireless monitoring of catheter biofilms

Abstract

A microfabricated flexible impedance sensor (FlexIS) for wireless monitoring of bacterial biofilm formation on catheters is presented. The system consists of interdigitated electrodes on flexible polyimide film, interfaced with the cylindrical surface of a urinary catheter. An AD5933 impedance converter (AIC) measures sensor impedance and enables wireless readout by communicating with a smartphone via Bluetooth. A 5% decrease in impedance at 1 kHz corresponded to the growth of an Escherichia coli biofilm for 24 hours on the catheter surface, compared to an increase of 2% for an unseeded control. Measurement results from the AIC and a standard potentiostat were compared, showing a similar decrease in impedance with biofilm formation. Furthermore, the sensor response to biofilm formation was supported by measured changes in biofilm biomass. The FlexIS allows in situ biofilm characterization in complex and inaccessible environments in clinical and research settings.