Label-free, real-time detecting and monitoring of drug dosage and bacteria

This report discusses the development of a miniaturized biosensor system that can be used for real-time monitoring of drug concentration and detection of pathogens in food or water samples. Conventional bacterial detection methods can take several hours or even days. This is because the bacteria need to be cultured over long periods to have large numbers of them for detection. In this report, a highly sensitive technique for counting and early detection of the growth of a colony from a single bacterium is discussed. An array of electrodes compatible with agar growth medium was prepared. A sample containing the bacteria was then cultured above the agar layer. The electrical properties of the medium were monitored using a lock-in-amplifier periodically. The data was collected using a microcontroller circuit. The variations in signal from various electrodes are compared against their initial states, revealing the presence of bacteria in the sample. This technique forms the basis of a label-free bacterial detection technique. Our technique could measure drug concentration of as low as 10pMol/mL and the detection time of bacterial growth reduced from 24 to less than 8 hours.