Authors:
Tiejun Miao
1
;
Shigeo Kaizu
2
;
Junji Kojima
3
and
Mayumi Oyama-Higa
4
Affiliations:
1
Chaos Technical Research Laboratory, Japan
;
2
Chaos Technology Research Laboratory, Japan
;
3
Rakuwakai Kyoto Music Therapy Research Laboratory, Rakuwakai Otowa Hospital, Japan
;
4
Osaka University, Japan
Keyword(s):
Plethysmograms, Largest Lyapunov Exponent, Nonlinear Analysis, HFLF Balance, Blood-vessel Balance.
Abstract:
The largest Lyapunov exponent (LLE) obtained through nonlinear analysis of plethysmograms contains information of the cerebral central system, which has been shown by mathematical model and experiments. Especially mental experiments have shown the significant relationship between LLE and mental status of an individual. The wave data are obtained by measuring changes in the blood flow of the capillary vessels of a fingertip, with an infrared sensor. Then the analogue format of the data is changed into digital format for calculation. Using “Lyspect” software, we next compute parameters including LLE, HF/LF, autonomic-nerve balance, and blood vessel age. These parameters, as functions of time, can be displayed in graphs. Notably, while the pulse wave is being measured, changes of LLE and HF/LF can be displayed in real time. Furthermore, the setup of measuring time and various parameters for calculation is available. The state at the time of the measurement can be studied by visualizatio
n. Additionally, the unsuitable wave data arising from the accuracy of the sensor and the external noise can be eliminated by the filter of Lyspect. Currently, a version of Lyspect that is installable on user-friendly smartphones is being developed, which will make even easier timely self-check of mental status.
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