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Kernel Flow
Photo: Han Y. Ban et al. (Kernel), J. Biomed. Opt. 2022 · CC BY 4.0 (opens commons.wikimedia.org)

Kernel Flow

by KernelUS

DeployStage 4 of 5

Sold to research groups; used in studies of thinking and brain aging.

Updated 3 Jul 2025Checked 25 Sep0 updates this week

Milestones

Next · Adopted in research and clinical studies
  1. Kernel Flow unveiled2020Complete.
  2. Technical paper published2022Complete.
  3. Adopted in research and clinical studiesNowCurrent milestone.

Most important updates

  • 3 Jul 2025
  • 20 Feb 2025
  • 30 Jul 2024
  • 2022
  • 9 Jul 2020

Current obstacles

  • Slow, indirect signalIt measures blood flow, which lags brain activity by seconds, and only reaches the brain's outer layer.

Physics limits

  • Light only reaches the outer brainNear-infrared light scatters heavily in scalp, skull and brain, so it samples only the outer cortex, about 1-2 cm below the scalp, never deep structures.
  • Blood is slower than thoughtBlood-flow changes lag neural activity by a few seconds and peak around 5 s, so the method can never follow millisecond-scale brain events.
  • Scattering blurs positionBecause photons bounce randomly, spatial detail is limited to roughly a centimetre, far coarser than MRI.

How it works

3 parts
An older light-based (fNIRS) cap on a model head: emitters and detectors on the scalp track blood oxygen, the principle behind Kernel Flow
An older light-based (fNIRS) cap on a model head: emitters and detectors on the scalp track blood oxygen, the principle behind Kernel FlowPhoto: Walej · CC BY-SA 4.0 (opens commons.wikimedia.org)
Pulse

Lasers flash into the head

Sources send near-infrared light pulses lasting trillionths of a second through the scalp and skull.

Time

Clock every returning photon

Detectors time each photon; ones that arrive later travelled deeper, which separates brain signals from scalp signals.

Map

Blood oxygen tracks activity

Changes in light absorption show oxygen-rich and oxygen-poor blood across the outer brain, which rise and fall with local activity.

Papers & demos

1 item
  1. 2022paper
    Kernel Flow: a high channel count scalable time-domain fNIRS system (J Biomed Optics) (opens doi.org)Technical description of the headset and how well it works.

Update log

5 updates

Thu 3 Jul 2025

  • Minor: PaperResearch

Thu 20 Feb 2025

  • Minor: PaperResearch

Tue 30 Jul 2024

  • Minor: PaperResearch

2022

  • Minor: PaperResearch

Thu 9 Jul 2020

  • Minor: PressFunding

About Kernel

The team behind Kernel Flow

Kernel

Kernel Flow brain-scanning headset

Los Angeles company founded by Bryan Johnson that makes headsets to measure the brain without surgery. Kernel Flow shines light through the scalp (fNIRS) to track blood-oxygen changes across the brain, in a wearable form.

kernel.com (opens kernel.com)Company profile →

Founded
201610 yrs
Headquarters
United States
Status
Private
Valuation
private
Works in
NeurotechNon-invasive
Coverage
1 program · 5 updateslatest 3 Jul 2025checked 25 Sep
People
Bryan Johnson (opens en.wikipedia.org)Founder
Primer