Abstract: The present disclosure encompasses the manufacture and use of rapid and inexpensive electrical biosensors comprising microelectrodes in a micro-channel. The devices of the disclosure can be used to detect and quantify target cells, protein biomarkers, and nucleic acid biomarkers, and the like, by measuring instantaneous changes in ionic impedance. The micro-channel devices of the disclosure are also suitable for the detection of target protein and oligonucleotide, and small molecule target biomarkers using protein-functionalized micro-channels for the rapid electrical detection and quantification of any type of target protein biomarker in a sample.