Schematic2 (IMAGE) University of Massachusetts Amherst Caption A stable pH gradient is generated between a pair of biased graphene microelectrodes. Molecules (red particles) are focused into a narrow band—the focusing plane—between the microelectrodes upon the pH-gradient generation. The focused molecules are detected at high sensitivity by pre-placing specific recognizers (green particles) at the focusing plane. Credit UMass Amherst Usage Restrictions none 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.