Cation- and anion-selective hydrogels (IMAGE) University of Oxford Caption Cation- and anion-selective hydrogels are the ionic equivalents of p- and n-type electronic semiconductors. Image credit: Yujia Zhang. Credit Yujia Zhang Usage Restrictions These images are for editorial purposes for the purpose of this press release ONLY and MUST be credited. They MUST NOT be sold on to third parties. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.