There are many industries that require localised erosive or etching processes; such as electronics fabrication, decorative glassware, engraving jewellery or even ‘stonewashing’ your favourite bluejeans.
What many of them need is a way to control exactly where and how much etching takes place. Well, every time I visit the dentist I’m told the salutary tale of how the surfaces of my teeth are being eroded by bugs that create acid from my food (I also get the spiel about the latest recommended new-and-improved brushing/flossing technique, but that’s another story),
Today’s invention therefore is to apply a precise concentration of sugar solution to a well-defined region and then to add some enamel eating bacteria. After a specified time (at a particular temperature), their acidic output will have etched a tightly controlled region of the surface.
It’s not going to be a fast process, but it seems pretty low-cost and there may be scope for recycling the bugs as well as the acids they produce.