The transfer of ions across cell membranes, e.g. the skin, due to the application of an electrical potential making the outer layer porous. Smart skin patches use iontophoresis to send drugs, nutrients, tattoos etc through the skin and advanced versions will record performance, permit different doses by time of day, or deliver according to monitored need and employ RFID to report it unambiguously identifying the source thanks to printed electronics. Versions from Power Paper of Israel employ screen printed electrodes. It has licensed seven major companies to produce and sell these. Birch point has a similar product that is offered for license. Both will need printed electronics to penetrate mass markets.