Serge is a contemporary of Don Buchla and Bob Moog and designed the first West Coast synthesizers that were sold as DIY kits. He invented the term "patch programmable" which means that his modules (and also Buchla's which were very similar) did not impose any particular musical function on the artist, but were open to experimentation and could be combined in many more ways than the "east coast" synth modules that Bob Moog and many others produced.
Here is the interview which I think is really beautifully done, hats off to Waveshaper TV
Especially interesting to note is that Serge mentions the "paperface" frontplates which he made to save money. This is very similar to the approach that robertlanger took in designing the faceplates for the AE Modular system. Also Serge took certain shortcuts to keep costs down and this exactly what the AE system also tries to achieve.