The Institute for Biophysical Dynamics 1 article published in JoVE Bioengineering Silicon Nanowires and Optical Stimulation for Investigations of Intra- and Intercellular Electrical Coupling Menahem Y. Rotenberg*1, Erik N. Schaumann*2, Aleksander Prominski1,2, Bozhi Tian1,2,3 1The James Franck Institute, The University of Chicago, 2Department of Chemistry, The University of Chicago, 3The Institute for Biophysical Dynamics, The University of Chicago This protocol describes the use of silicon nanowires for intracellular optical bio-modulation of cell in a simple and easy to perform method. The technique is highly adaptable to diverse cell types and can be used for in vitro as well as in vivo applications.