Ion exchange membranes are a key part of many electrochemical systems, from metal recovery and water treatment to fuel cells and flow batteries. Commercial membranes like Nafion can cost hundreds of dollars per square meter, which puts a lot of useful chemistry out of reach for small labs, startups, and DIY builders.

This project is the fully open-source design and process for a homogeneous ion exchange membrane you can make from inexpensive, off-the-shelf precursors. No specialized suppliers and no industrial equipment are required, and the goal is to drop the cost to a few dollars per square meter.

The membrane is one part of SEM TECH, a closed-loop electrochemical system built by Rowow LLC in Lake Wales, Florida, that recovers critical minerals, precious metals, and rare earths from ore, mine waste, and e-waste. Everything is released under CERN-OHL-S v2. Full build guide, license details, and support links are in the project details and links below.