Biotinylated DNA hairpin binding streptavidin. A DNA hairpin "gauge" is designed to offer a clear multi-level modulated blockade signal. The DNA gauge has it's hairpin loop section altered from the 4 dT loop used in the controls, the loop has a linkage to biotin placed in the middle of it's 4 dT loop (see Methods). One of these DNA hairpins with attached biotin is captured in the channel, an excess of Streptavidin is introduced. Transition to a new blockade state is quickly seen, one only seen after introduction of streptavidin.