• CustomArray’s electrochemical DNA-synthesis platform uses CMOS chips with thousands of individually addressable micro-electrodes to generate acid in situ, performing detritylation and growing distinct oligonucleotides in parallel; the resulting 15 million-base oligo pool is quoted at ~$6 k, but the cleaved oligos mix into a single solution, preventing downstream positional assembly.

• Participants debated why a yeast-cannabinoid project consumed $2 M and 10 years, concluding that the bottleneck is not DNA-writing cost but the absence of high-throughput combinatorial experimentation and tacit biological know-how.

• Rapid-fire engineering concepts for next-generation DNA printers included 1 MHz ink-jet valves, surface-acoustic-wave (SAW) resonators for 100 MHz droplet generation, laser ablation of unwanted mid-air drops, electrostatic steering, magnetohydrodynamic pumping, and repurposing decapped SRAM dies as micro-printheads.

• The Ma et al. 2017 Nature paper on CRISPR editing of human embryos was discussed alongside immediate biorxiv rebuttals questioning whether inter-homologue repair actually occurred and whether mosaicism had been adequately ruled out.

• The SRC SemiSynBio program solicitation (proposals due Oct 2017) was noted with surprise that DNA synthesis technologies were absent from the call, despite their centrality to synthetic biology.

• Key open technical questions about electrochemical synthesis include achievable error rates, step yields, cost per base, and scalability to “a billion electrodes”; participants called for a comparative metrics table across synthesis methods.

• Relevant patents for electrochemical DNA synthesis include US 6,280,595 (CombiMatrix, 1999) and US 2006/0127920 (Church lab, ~2005); CustomArray holds additional IP that may block open development.

• Practical notes and protocols for DIY electrochemical DNA synthesis are being collected at http://diyhpl.us/wiki/dna/synthesis/notes/, and earlier discussion logs are archived at http://gnusha.org/logs/2015-07-13.log.