alternative circuit fabrication
Silver, inkjet, graphite, latex, etc. Take my commentary with a grain of salt, I am not an expert in chemistry.
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.
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.
- Instant inkjet circuits: lab-based inkjet printing to support rapid prototyping of UbiComp devices
- RFID Tag and RF Structures on a Paper Substrate Using Inkjet-Printing Technology
- Ink-jet fabrication of electronic components
- Preparation of solid silver nanoparticles for inkjet printed flexible electronics with high conductivity
Graphite is moderately conductive (you can draw crappy circuits with a pencil), very cheap, easily acquired, and the basis of many conductive glues.