Eventually, he decided to look at using “air logic“. Air logic uses pneumatic devices to create relays, limit switches, AND gates, NAND gates ... was to build a multiplexer whose elements ...

This paper designs an 8:1 multiplexer with CMOS Transmission Gate Logic (TGL) using the power gating technique, which reduces the leakage power and leakage current in active mode. Power gating ...

While it is true that you can build logic gates using ... NAND gate) and then the logic was all in how you wired them together. And in this context, the SPDT relay was used as a two input ...