Implantable brain electrophysiology electrodes are valuable tools in both fundamental and applied neuroscience due to their ability to record neural activity with high spatiotemporal resolution from shallow and deep brain regions. Their use has been hindered, however, by the challenges in achieving chronically stable operations. Furthermore, implantable depth neural electrodes can only carry out limited data sampling within predefined anatomical regions, making it challenging to perform large-area brain mapping. Minimizing inflammatory responses and associated gliosis formation, and improving the durability and stability of the electrode insulation layers are critical to achieve long-term stable neural recording and stimulation. Combining electrophysiological measurements with simultaneous whole-brain imaging techniques, such as magnetic resonance imaging (MRI), provides a useful solution to alleviate the challenge in scalability of implantable depth electrodes. In recent years, various carbon-based materials have been used to fabricate flexible neural depth electrodes with reduced inflammatory responses and MRI-compatible electrodes, which allows structural and functional MRI mapping of the whole brain without obstructing any brain regions around the electrodes. Here, we conducted a systematic comparative evaluation on the electrochemical properties, mechanical properties, and MRI compatibility of different kinds of carbon-based fiber materials, including carbon nanotube fibers, graphene fibers, and carbon fibers. We also developed a strategy to improve the stability of the electrode insulation without sacrificing the flexibility of the implantable depth electrodes by sandwiching an inorganic barrier layer inside the polymer insulation film. These studies provide us with important insights into choosing the most suitable materials for next-generation implantable depth electrodes with unique capabilities for applications in both fundamental and translational neuroscience research.

Lightweight strong aerogels have many applications, but they suffer from the trade‐off between key mechanical properties, and it remains challenging to realize superelastic aerogels simultaneously possessing high strength and excellent structural recovery. Herein, a strategy to overcome such a problem by designing a carbon nanotube (CNT)‐based aerogel consisting of flexible‐rigid core‐shell structure, which achieve a combination of excellent properties including superelasticity (complete recovery at 90%), high strength (over 12 MPa at 90%) and wide tunability (from 101 kPa to 4.5 MPa at 50% strain), is presented. It is found that the outer rigid but brittle amorphous carbon shells crosslink the CNT cores and crack into orderly distributed segments during the first compression cycle, while the flexible CNT cores ensure the integrity of the overall skeleton and tolerance to large deformation. This designed CNT composite sponges exhibit overall superior mechanical properties than previously reported foams/aerogels, and due to such unique crack‐induced superelasticity mechanism, potential applications such as pressure sensors with wide‐range tailored sensitivity and high‐performance energy absorbers have been developed. This flexible‐rigid core‐shell synergia may provide further insight for tunable high‐strength aerogel design and innovative applications.