Neural Noise

Wearable fNIRS for real-time cognitive fatigue tracking

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  • A wearable fNIRS sensor was reported to track cognitive fatigue in real time (Spectroscopy Online, 2025).1
  • The system provides real-time hemodynamic monitoring with a portable form factor suited to out-of-lab use.1 1

Weekly enrichment (2026-07-20)

  • The device was reported in a peer-reviewed study in MDPI Biosensors (2025, 15(2):92) and a Preprints.org preprint by Mauro Victorio, James Dieffenderfer, Tanner Songkakul, Josh Willeke, Alper Bozkurt, and Vladimir A. Pozdin (Florida International University, North Carolina State University, and Rose-Hulman Institute of Technology).2 3
  • It integrates the full functional near-infrared spectroscopy (fNIRS) system into a bandage-sized wireless unit worn on the forehead, using a 19 × 44 mm circuit board fixed with medical film dressing (3M Tegaderm) and streaming raw data over Bluetooth Low Energy to a smartphone or laptop.3
  • Power comes from a 3.7 V lithium-ion battery; a 500 mAh cell supports roughly 50 hours of continuous operation at a 10 Hz sampling rate, with a “DeepSleep” mode to extend battery life for intermittent use.3
  • Sensor fidelity was validated with arterial-occlusion and breath-holding tests, where it recorded the expected drops in oxygenated hemoglobin (HbO) and spikes in deoxygenated hemoglobin (HbR) followed by recovery, comparable to full-scale benchtop NIRS and fMRI benchmarks.2 3
  • During prefrontal-cortex arithmetic tasks, some participants showed increased oxygenation with cognitive effort while others decreased under higher workload; one participant’s signal shifted mid-study, which the authors interpret as progressing cognitive fatigue detectable without post-processing, supporting edge-computing use.2
  • The system detected very-low-frequency (VLF) changes in the hemoglobin signals related to mental-task performance, and the authors target unsupervised daily-life monitoring for applications in driving, military/aerospace cockpits, and classrooms.2 3
  • Broader evidence supports HbO as a fatigue biomarker: a systematic review and meta-analysis of fNIRS studies (Yan et al., Psychophysiology, 2024/2025; DOI 10.1111/psyp.14747) found significant prefrontal-cortex activation, particularly a rise in HbO, as a robust indicator of mental fatigue independent of the fatigue-induction type or pre-trial training.4
  • Machine-learning BCI work has used two-channel wearable fNIRS placed at F7/F8 (10-20 system) with user-tuned classifiers to detect cognitive-fatigue states at about 70.91 ± 13.67% accuracy, underscoring both the promise and the need for per-subject calibration in real-world deployment.5

Footnotes

  1. https://news.google.com/rss/articles/CBMioAFBVV95cUxQdkQ4S2p1S0k2SGdIRkRhdXByak9GVmhLWGhfVHN1aHJ4Y0xpVGxScEZueGVuZ1ZCRkpJUUczbTVqVFZIU1lTeGlST08xcGpzSTFEa1FPb1hVYVpENF9rLTY0QU9YdmUwal9nNjUybW1BcVRLY0VsdmxvbmVHYTZ3WnlKS0pNZWw2aE1qUzFhM1hTVmszTHpNTFkzSFFacXZV?oc=5 ↩ ↩2 ↩3

  2. https://www.spectroscopyonline.com/view/wearable-fnirs-sensor-tracks-cognitive-fatigue-in-real-time ↩ ↩2 ↩3 ↩4

  3. https://www.mdpi.com/2079-6374/15/2/92 ↩ ↩2 ↩3 ↩4 ↩5

  4. https://doi.org/10.1111/psyp.14747 ↩

  5. https://www.mdpi.com/1424-8220/22/11/4010 ↩

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