Highly Conformable Conducting Polymer Electrodes for In Vivo Recordings

Electronic devices that interface with living tissue have become a necessity in clinics to improve diagnosis and treatments. Devices such as cardiac pacemakers and cochlear implants stimulate and monitor electrically active cells, restoring lost function and improving quality of life. On a more fundamental level, most breakthroughs in our understanding of the basic mechanisms of information processing in the brain have been obtained by means of recordings from implantable electrodes. [ 1–3 ] Materials science is playing a pivotal role in this fi eld. For example, state-of-the-art implantable electrodes are microfabricated devices that contain high-density arrays of metal sites on a silicon shank (silicon probes). [ 4 ] Still, as neuroscience continues to advance and more options for electrical intervention become a reality for patients (ocular implants, deep-brain stimulation for epilepsy and Parkinson’s disease), [ 5 ] there is a tremendous need for developing advanced materials solutions for the biotic/abiotic interface. One such example is the necessity to develop electrodes that can conform to the curvilinear shapes of organs (e.g., the surface of the brain or its sulci) and form high-quality electrical contacts. Such surface electrodes are needed for electrocorticography (ECoG), which is increasingly used for functional mapping of cognitive processes before certain types of brain surgery (e.g., tumors) or for diagnosis purposes (e.g., epilepsy). [ 6 ] Placed on the somatosensory cortex, surface electrode arrays are also being used in brain-machine interfaces, an assistive technology for people with severe motor disabilities. [ 7 ] In contrary to silicon probes that penetrate the brain and cause tissue damage, these arrays are placed on the surface of the brain and are hence less invasive.