Woo-Bin Jung carefully programmed a tiny silicon chip in a Cambridge lab, its surface no bigger than a fingernail, to write 64 unique strands of DNA—each a precise sequence of genetic code—using nothing but water and controlled electric currents. This wasn’t chemistry in the traditional sense; it was biology choreographed by electronics. At the Harvard John A. Paulson School of Engineering and Applied Sciences, Donhee Ham and his team have reimagined how DNA is made, breaking a critical bottleneck in synthetic biology. For decades, custom DNA has been produced using phosphoramidite chemistry—a process reliant on toxic solvents and centralized factories. Now, for the first time, researchers have demonstrated a water-based alternative that synthesizes 64 distinct DNA sequences in parallel, each up to 39 nucleotides long, using a silicon chip embedded with 64 ring-shaped electrode pairs. This leap—four times more sequences than previously possible with enzymatic methods—opens the door to decentralized, safer, and more sustainable DNA production. The chip works by precisely controlling pH at microscopic sites: in each synthesis cycle, electric current is driven through an inner electrode ring to generate protons, locally lowering pH to trigger enzymatic addition of a nucleotide. Simultaneously, the outer ring absorbs stray protons, preventing unwanted reactions nearby. Cycle after cycle, this electrochemical precision builds custom DNA strands, one nucleotide at a time. The technology’s roots lie in neuroscience—Jeffrey Abbott originally designed the chip to record from thousands of neurons. But Ham’s team realized the same current control could manipulate molecules, not just cells. They repurposed the chip’s architecture, replacing neuron-facing electrodes with ring pairs optimized for pH localization. The result is a bridge between microelectronics and molecular biology. Beyond immediate applications in diagnostics and synthetic biology, the team encoded a 169-byte message into the synthesized DNA—proof that this system could one day contribute to DNA data storage, a technology capable of preserving exabytes of information in a single gram of DNA. While massive scale remains a challenge, the environmental promise of water-based synthesis grows more compelling as demand for DNA rises. This isn’t just a lab curiosity—it’s a blueprint for a greener bioeconomy.