The two major approaches to DNA synthesis are chemical synthesis using phosphoramidite and enzymatic synthesis using Terminal deoxynucleotidyl Transferase (TdT). Chemical synthesis using phosphoramidite though a highly efficient technology is still relatively limited in the length of nucleotides they are able to synthesize (< 300 nucleotides in length). Enzymatic synthesis using TdT which is often used as an alternative to phosphoramidite, is a template-free method that works by affixing to an initiator and then initializing polymerization. However, this method is often less controlled compared to methods using phosphonamidite, which are able to add nucleotides in a more controlled step-wise manner.
By combining approaches of template-free DNA synthesis with current chemical approaches using microfluidic chips, this technology seeks to improve controllability of DNA synthesis while also allowing synthesis of larger oligonucleotides.