Abstract: An apparatus for characterizing and identifying individual particles, including: an input reservoir; at least one output reservoir; a channel connecting the input reservoir to the at least one output reservoir, wherein the channel is functionalized with at least one molecule selected to interact with a marker on a surface of a particle; a system to move fluid containing the particle from the input reservoir through the channel and into the at least one output reservoir; and a system to measure the period of time during which the particle moves through the channel. The particle may optionally be a cell, the at least one molecule may be a protein functionalized onto the channel to interact with the protein on the surface of the cell so as to slow passage of the target cell through the channel. By measuring the period of time during which the particle takes to move through the channel, the particle can be characterized and thereby identified.