Structural differentiation of common bacteria using impedance spectroscopy

Microbiological impedance spectroscopy has been employed for several decades to determine the presence and concentration of known bacteria and pathogens. Recent interest in lab-on-a-chip technology has been the motivation to develop miniature, accurate and rapid instrumentation to identify various strains of bacteria thus minimizing the necessity to culture, stain and perform population counting in a laboratory environment. In this work, a substrate using borosilicate microscope slides containing interdigitated electrodes was implemented to measure the real and imaginary impedance components of thin-film bacterial suspensions in the time domain. The resultant resistance and reactance changes that occur in real time appear to be characteristic of the cell wall composition that differentiates gram positive from gram negative bacteria.