In january 2018, researchers from Southhampton have enhanced the memristors. They ware able to store 128 discernable memory states per switch. The group of Themis Prodromakis evaluated different compositions of functional oxide materials.
The full article is available in this link: https://www.electronicsweekly.com/news/research-news/southampton-breaks-memristor-record-7bits-cell-2018-01/. Another report can be found hier: https://www.southampton.ac.uk/news/2018/01/memristors-breakthrough.page
We are already excited to see the papers and their presentation on ISCAS 2018.