Rapid detection of E. coli cells in urine samples using a self-capacitance touchscreen device

Escherichia coli is one of the main causes of urinary tract infections (UTIs). E. coli is commonly detected from urine using standard culture method. However, the urine sampling and analysis required for these methods can be costly, time consuming (requires 24 to 48 hours) and labor-intensive. This work proposes a capacitive touch screen sensor concept as possible alternative device for rapid detection of E. coli in urine samples. E. coli solutions prepared at different concentrations and urine samples (with spiked and nor spike E. coli) obtained from healthy women participants, have been analyzed using a capacitance evaluation kit. It has been demonstrated in this study that the use of this evaluation kit provides a low-cost and simple alternative system for detecting E. coli present in urine. Several experimental tests were performed to determine the optimal testing volume, the sensitivity of the sensor, limit of detection and repeatability. The optimal testing volume was 80 microliters and the analytical sensitivity was 17 counts per picofarad (pF). The lowest detectable concentration is around 3.98 × 10⁵ CFU/ml. The repeatability (r) was found to be 7.2 or 6.2 % (in r%). The capacitive touch sensor gave promising results that could be used to design and realize a portable diagnostic device for early-stage detection of UTIs.