U.S. Army Center for Environmental Health Research 1 article published in JoVE Environment Preparation and Testing of Impedance-based Fluidic Biochips with RTgill-W1 Cells for Rapid Evaluation of Drinking Water Samples for Toxicity Linda M. Brennan1, Mark W. Widder1, Michael K. McAleer2, Michael W. Mayo2, Alex P. Greis2, William H. van der Schalie1 1U.S. Army Center for Environmental Health Research, 2Nanohmics, Inc. This manuscript describes how to prepare fluidic biochips with Rainbow trout gill epithelial cells for use in a field portable electric cell-substrate impedance sensor. The protocol for running a rapid drinking water toxicity test with the sensor is also described.