In this podcast episode, MRS Bulletin’s Stephen Riffle interviews Jennifer Gelinas, an assistant professor in the Department of Neurology and Institute for Genomic Medicine at Columbia University Irving Medical Center, and Dion Khodagholy, an associate professor in the Department of Electrical Engineering at Columbia University, about their ionic communication system for implantable devices. The system involves building a capacitor using water ions and biomolecules. With the placement of two conducting electrodes in the body and introduction of an alternating current, the tissue between the electrode will act as an electrolyte medium. Together, these two electrodes and their electrolyte medium form a capacitor that is capable of generating a detectable electrical field. The ionic communication device is fabricated with materials that have already been shown to be safe in the body, such as gold and a semiconducting plastic—poly(3,4-ethylenedioxythiophene)–polystyrenesulfonate or PEDOT:PSS. This work was published in a recent issue of Science Advances (doi:10.1126/sciadv.abm7851).