In order to detect diseases like cancer at an early stage while it still may be curable, it's necessary to develop a diagnostic technique which can rapidly and inexpensively detect protein and nucleic acid biomarkers, without making any sacrifice in the sensitivity. We have developed a technique, based on the use of bioactivated microfluidic channels integrated with electrodes for electrical sensing, which can be used to detect protein biomarkers, target cells, and DNA hybridization. In this paper, we discuss the theoretical detection limits of this kind of sensor, and also discuss various experimental considerations in the electrical characterization of our device. In particular, we discuss the temperature dependence, the impedance drift, the noise sources, and various methods for optimizing the signal to noise ratio.