Electrochemical biosensing devices and methods detect the activity of proteases and active infection in biological samples. The devices and methods utilize distance constraints between a redox reporter and an electrode to create a change in current that is detected. The distance constraints are released when an analyte containing a specified protease or proteases reacts with a protein substrate sequence in the analyte. The particular protease or proteases to be detected can be selected by using biosensors with particular substrate sequences. The devices and methods are not only qualitative, they can be used to quantitatively evaluate protease content in samples.