hardware / software / wetware

alternative circuit fabrication

Silver, inkjet, graphite, latex, etc. Take my commentary with a grain of salt, I am not an expert in chemistry.

why bother?

Etching PCBs at home involves unpleasant chemicals and is not entirely environmentally friendly, while commercially manufactured boards are either cheap and have slow shipping, or cost too much. Milling PCBs is faster, but is noisy, messy, and the machines seem pricey in both initial cost and upkeep (drill bits etc.). An inkjet-printed board could have a turnaround time of less than twenty minutes (5 for printing, 15 for sintering), for pennies per unit and low upfront costs. Additionally, the light weight, flexibility, and other properties of paper and plastic films allow interesting new design approaches and applications.

silver nanoparticles

Inkjet circuit fabrication via depositing silver. This is done either by printing precursors (e.g. silver nitrate and ascorbic acid) onto the substrate, or by directly printing the silver nanoparticles (which may have some coating to prevent oxidation). The former has less risk of clogging the nozzles, while the latter doesn't leave any precursors embedded in the end product and is simpler. A sintering step is commonly used to fuse the nanoparticles, greatly increasing conductivity, which may be as simple as using an oven, or may be done via various chemical processes.

graphite powder

Graphite is moderately conductive (you can draw crappy circuits with a pencil), very cheap, easily acquired, and the basis of many conductive glues.