Three ways into the brain
BCIs trade off signal quality against surgical risk. Penetrating arrays (Neuralink) read the most; surface arrays (Precision) sit on the brain; vascular devices (Synchron) avoid open-brain surgery entirely. The tracker compares all three.
There is no single "brain chip." The implants in this tracker take three very different routes into the brain, and the differences explain most of the debate about which approach wins.
Penetrating arrays insert tiny electrodes into brain tissue. Neuralink's N1 threads 64 fibers carrying 1,024 electrodes into the motor cortex, reading individual neurons at high resolution — the richest signal, but it requires opening the skull and placing hardware in the brain itself. Surface arrays instead lay a thin film on top of the cortex: Precision Neuroscience's Layer 7 also carries 1,024 electrodes but slides through a sub-millimeter slit and can be removed, trading some signal for reversibility, which helped it become the first such device with FDA clearance. Vascular devices avoid brain surgery altogether — Synchron's Stentrode is threaded up a blood vessel and reads through the vessel wall with far fewer channels, accepting a coarser signal for a much lower surgical bar.
More electrodes mean more potential bandwidth, which is why the tracker records channel counts. But channels are not the whole story: a safer, lower-resolution device that more patients will accept can reach the clinic faster than a higher-bandwidth one that requires riskier surgery. That tension — signal versus safety — is the real contest, and it is why we track patients implanted alongside electrode counts.