I show you here a cuff type electrode that was self-sizing, meaning the internal diameter of the cuff could adapt to being placed on a nerve with a larger or smaller outside diameter1,2. When unrolled it was a flat structure and when that was released it naturally curled around itself and a nerve. Pressures around the electrode were believed to cause the structure to adapt to a nerve of smaller diameter and when implanted on a nerve with a diameter larger than the natural diameter of the cuff the spiral cuff could adapt.
1Gregory G. Naples, “Implantable Spiral Cuff Electrode for Electrical Stimulation of Peripheral Nerve” MS Thesis CWRU Department of Biomedical Engineering, 1987
2Donald G. Atzberger, “Tissue Response to Implanted Self-Sizing Spiral Cuff, MS Thesis, CWRU, Departments of Chemical Engineering and Biomedical Engineering, 1998.