This work reports on the creation of an electroencephalogram (EEG) index and the discovery of a power ratio related to alpha band frequencies (8–13 Hz) that were experimentally found to have a high correlation with human mental fatigue. The EEG was measured from occipital lobe of the human brain by microfabricated dry candle-like microneedle electrodes (CMEs) that can avoid hairs and penetrate through the high-impedance stratum corneum. The newly identified EEG index exhibited higher correlations to mental fatigue states, which were rated subjectively via the visual analogue scale (VAS), than did heart rate variance, which is often used as the objective measure of fatigue levels. Interestingly, it was found that the index trend changed 10 min before the VAS did, which implies that the index could assess the onset of mental fatigue even before the subjects recognised it themselves. The identification of this EEG index, along with the ease of obtaining EEG measurements via CME, which is due to the fact that the CME does not require any skin preparation or conductive gels and can acquire EEGs from hair-covered parts of the scalp, can be expected to promote practical fatigue assessment applications that use EEGs.

References

1. 1)
  - 10. Lal, S.K.L., Craig, A.: ‘Psychophysiological effects associated with drowsiness: driver fatigue and electroencephalography’, Int. J. Psychophysiol., 2000, 35, (1), p. 39.
2. 2)
  - 19. Hayashi, H.: ‘Shinpaku Hendou no Rinsyou Ouyou: Seiriteki Igi, Byoutai Hyouka, Yogo Yosoku (Clinical Application of Heart Rate Variance: Physiological Significance, Diagnosis, Prognosis Prediction)’ (Igaku Syoin, 1999).
3. 3)
  - 13. Arai, M., Nishinaka, Y., Miki, N.: ‘Electroencephalogram measurement using polymer-based dry microneedle electrode’, Jpn. J. Appl. Phys., 2015, 54, (6S1), p. 06FP14 (doi: 10.7567/JJAP.54.06FP14).
4. 4)
  - 18. Japan Society of Fatigue Science: ‘Guideline of anti fatigue evaluation’ (Japan Society of Fatigue Science, 2011). Available at http://www.hirougakkai.com/guideline.pdf, accessed 22 February 2016].
5. 5)
  - 20. Fukuyo, H.: ‘Change of the R-R intervals of heart beat for mental stress and physical stress’, Shinshinkenkoukagaku, 2012, 8, (2), pp. 130–142.
6. 6)
  - 5. Stern, J.M.: ‘Atlas of EEG patterns’ (Lippincott Williams & Wilkins, 2005).
7. 7)
  - 8. Craig, A., Tran, Y., Wijesuriya, N., et al: ‘Regional brain wave activity changes associated with fatigue’, Psychophysiology, 2012, 49, (4), pp. 574–582 (doi: 10.1111/j.1469-8986.2011.01329.x).
8. 8)
  - 22. Sotooka, T.: ‘Uchida-Kraepelin Seishin Test: Kiso Text, 9th ed. (Uchida-Kraepelin Mental Test: Fundamental Text, 9th ed.)’ (Kinmei Insatu, 1973).
9. 9)
  - 3. Tanaka, M., Ishii, A., Watanabe, Y.: ‘Effects of mental fatigue on brain activity and cognitive performance: a magnetoencephalography study’, Anat. Physiol., 2015, s4, pp 1–5 (doi: 10.4172/2161-0940.S4-002).
10. 10)
  - 15. Nishinaka, Y., Jun, R., Prihandana, G.S., et al: ‘Fabrication of polymer microneedle electrodes coated with nanoporous parylene’, Jpn. J. Appl. Phys., 2013, 52, (6S), p. 06GL10 (doi: 10.7567/JJAP.52.06GL10).
11. 11)
  - 9. Grandjean, E.: ‘Fatigue in industry’, Br. J. Ind. Med., 1979, 36, (3), pp. 175–186.
12. 12)
  - 14. Arai, M., Kudo, Y., Miki, N., et al: ‘Polymer-based candle-shaped microneedle electrodes for electroencephalography on hairy skin’, Jpn. J. Appl. Phys., 2016, 55, (6S1), p. 06GP16 (doi: 10.7567/JJAP.55.06GP16).
13. 13)
  - 16. Wang, L.-F., Liu, J.-Q., Yan, X.-X., et al: ‘A MEMS-based pyramid micro-needle electrode for long-term EEG measurement’, Microsyst. Technol., 2013, 19, (2), pp. 269–276 (doi: 10.1007/s00542-012-1638-2).
14. 14)
  - 7. Ray, W.J., Cole, H.W.: ‘EEG alpha activity reflects attentional demands, and beta activity reflects emotional and cognitive processes’, Science, 1985, 228, (4700), pp. 750–752 (doi: 10.1126/science.3992243).
15. 15)
  - 2. Kurakake, H., Inoue, M., Watanabe, K.: ‘Abunai! ‘Mansei Hirou’ (Be careful! ‘Chronical fatigue syndrom’)’ (Nihon Housou Syuppan Kyoukai, 2004).
16. 16)
  - 17. Sanei, S., Chambers, J.A.: ‘EEG signal processing’ (Wiley, 2008).
17. 17)
  - 4. Teplan, M.: ‘Fundamentals of EEG measurement’, Meas. Sci. Rev., 2002, 2, (2), pp 5–7.
18. 18)
  - 1. Fukuda, K.: ‘The chronic fatigue syndrome: a comprehensive approach to its definition and study’, Ann. Intern. Med., 1994, 121, (12), p. 953 (doi: 10.7326/0003-4819-121-12-199412150-00009).
19. 19)
  - 6. Shimizu, N., Saito, T., Hukumoto, K.: ‘Research of the mental fatigue reduction effect color-light environment control’, Res. Rep. Nagaoka Univ. Technol., 2003, 25, pp. 87–91.
20. 20)
  - 21. Kurakaki, H.: ‘Establishment of subjective fatigue diagnostic method and guide production of chronical fatigue diagnosis for patients complained chronical fatigue with autonomic dysfunction’, Ministry of Health, Labour and Welfare, 2013.
21. 21)
  - 8. Jap, B.T., Lala, S., Fischerb, P., et al: ‘Using EEG spectral components to assess algorithms for detecting fatigue’, Expert Syst. Appl., 2009, 36, pp. 2352–2359 (doi: 10.1016/j.eswa.2007.12.043).
22. 22)
  - 12. Searle, A., Kirkup, L.: ‘A direct comparison of wet, dry and insulating bioelectric recording electrodes’, Physiol. Meas., 2000, 21, (2), pp. 271–283 (doi: 10.1088/0967-3334/21/2/307).

Fatigue assessment by electroencephalogram measured with candle-like dry microneedle electrodes

References

Related content