This isn't a "microphone" at all. Microphones by definition transduce the physical movement of sounds waves into a signal. This is just using the sound card to sample the electrical signals picked up by the conductive leads.
The title is a word play summarizing the fact that the author used such an amp to record biological signals. In context, it doesn't means or even imply that he uses a microphone.
Edit: word play, not pun; Edit2: +s; 3: better still.
Editing, anyway.
edit: that part meant jokingly (please). Although https://en.wikipedia.org/wiki/Old_English_grammar#Pronouns is far more interesting.