Beyond the scalp
The invasive, neuromodulation, materials, and wet-lab frontier. Most of it happens inside a lab.
Scalp EEG is one small corner of the field. The largest market is neuromodulation, the most dramatic results are intracortical, and the hardest unsolved problems are materials and packaging. This phase is a guide to that territory, with projects that mostly require a lab and a mentor.
Everything before this phase could be done in a dorm room. This phase cannot, and it should not be. Stimulating tissue, fabricating microelectrodes, and recording from animals belong in a lab with a mentor, an IRB or IACUC protocol, and a safety officer. The projects here are written for the student who has climbed the research ladder from Phase 1 and is now trusted with real equipment.
If you are not there yet, read the explainers anyway. Understanding neuromodulation mechanisms, stimulation safety, the foreign body response, and the industry landscape is what makes you useful in an interview at any of the companies thirty minutes from campus.
There is no “ready when” that ends this phase, because this is where the field itself currently ends.
Projects
Choose one. Do a second if hooked.Project A: Electrode fabrication
PEDOT:PSS coatings that drop a microelectrode's impedance tenfold, electroplating, impedance spectroscopy, carbon fibre microelectrodes, and flexible polyimide arrays in the nanofab. The materials spine, hands on, in a lab.
ProjectlabProject B: Build a lab a rig
An Open Ephys compatible headstage, a behaviour box, an optogenetics LED driver, a Bpod-style state machine. Labs are full of unbuilt instruments, and building one is how an undergraduate becomes indispensable.
ProjectProject C: Other windows on the brain
A DIY fNIRS prefrontal band, which is a pulse oximeter pointed at the cortex, and in-ear EEG on a custom earpiece, the frontier for sleep and consumer wearables. Two modalities almost nobody builds as a student.
ProjectProject D: Stimulation, studied properly
Design a charge-balanced current-source stimulator, drive electrodes in a saline bath, measure the voltage waveform and the electrochemistry, and understand the Shannon limit. Everything about stimulating tissue except the tissue.
ProjectProject E: Intracortical data
Human motor cortex recordings from published BCI studies, downloaded free. Spike sorting, local field potentials, and a decoder on the real thing. The end of the road that started with a cockroach leg.
Explainers
Theory that attaches to what you just built. Read after doing.Neuromodulation, mechanisms and evidence
Deep brain stimulation, spinal cord stimulation, vagus nerve stimulation, cochlear and retinal implants, focused ultrasound, TMS, and tDCS. What each does to tissue, what the evidence says, and the honest state of "we do not fully know why it works."
ExplainerStimulation safety and electrochemistry
Charge density, the water window, the Shannon limit, charge balance, and why stimulation electrodes corrode. The chemistry at the interface when you push current the other way.
ExplainerElectrode materials and the foreign body response
What the brain does to a thing pushed into it, why recordings degrade over years, and the materials strategies (softer, smaller, coated, dissolving) being tried against it. The central engineering problem of chronic implants.
ExplainerPackaging, power, and telemetry
Sealing electronics against body fluid for decades, getting a hundred channels through the seal, powering an implant without wires, and sending the data out. The unglamorous problems that decide whether a brain implant is a product.
ExplainerThe Utah Array, a history
From a Utah bioengineering lab in the late 1980s to the electrode in nearly every human intracortical BCI study, with the company, the regulatory path, and the limits that the next generation is trying to pass. Local history that happens to be the field's history.
ExplainerThe industry landscape
Who is building what, from implanted BCIs to neuromodulation giants to consumer headbands to research hardware, what each hires for, and how to read the field's news without being fooled. Dated, and meant to be re-checked.
Ready for Phase 7 when
Checks save on this deviceWhat an interviewer would ask
If you can answer these, you are done here- Why does a recording from a Utah Array degrade over years, and what are the leading approaches to fixing it?
- What is the Shannon limit and what does it not tell you?
- Compare DBS, spinal cord stimulation, and vagus nerve stimulation: mechanism, indication, and market.
- How would you design a hermetic feedthrough for a hundred channels? What has stopped people?