One of the big names in the torpedo experiments business was, of course, Matthew Fontaine Maury. He seems to have concentrated on the electrically-fired varieties.
A very interesting book on the lower-tech side is John C. Wideman's The Sinking of the USS Cairo (University Press of Mississippi, 1993) which firmly establishes that the weapon that sank the first warship to be sunk by a mine in actual combat conditions was a device triggered by a friction primer, rather than an electrically-fired torpedo (which is what often pops up in the histories, because that's how the Union officers reported it-- not realizing that the wires they saw were there to hold the torpedoes in place, rather than electrical wires).