Left Panel: A lipid bilayer supports the alpha-hemolysin heptamer that creates a pore, or channel used to collect the data, as shown left. The channel is supported by an aperture, which allows the flow of ions between cis (here, left) and trans (here, right) wells. Right Panel: The assembled α-hemolysin pore shown to scale, with a captured dsDNA molecule. As shown, the double stranded form is too wide to pass through the pore, while a single strand may pass through. Bottom Panel: First 100 ms blockade patterns of four DNA hairpins, part of a test set of nine base-pair hairpins, with 4dT hairpin loops, that have been studied extensively, and an eight base-pair control. The nine base-pair molecules only differ in their terminal base-pairs, yet their channel current blockade signals, "signatures", are easily resolved .