アモルファス磁歪ワイヤのＳＩ効果加速度センサーによる脳活動時系列計測

Abstract

A time series reflecting human brain activities was detected by using a sensitive micro-acceleration · inclined-angle sensor composed of a CoSiB magnetostrictive amorphous wire connected to a CMOS IC circuit with a resolution of about 0.1 Gal and 0.2°. A small sensor head using a glass specimen of 0.16 mm thick, 3 mm wide, and 15 mm long to which were attached a CoSiB amorphous wire of 20 μm diameter and 5 mm length and an inertia mass of 0.1 g was fixed to the center of a subject’s forehead.The detected waveforms of the sensor output for subjects with both eyelids closed differ from the microvibration would be classified into the following four kinds of states:(1) An almost flat waveform indicates that the subject is in a resting state or a sleeping state.(2) Passively stressful states such as recalling sad memories, being obliged to perform an unpleasant task, or performing a mental calculation generate a large stepwise wave with some irregular pulsing waves.(3) Actively stressful states such as finding a good idea and focusing on inventing something are indicated by high-frequency pulsing waves.(4) Pleasant states such as recalling happy memories of childhood or thinking about a favorite hobby are indicated by rhythmical waves without pulses.These signals reflecting a subject’s mental and emotional states (which we call a mechano-encephalogram) are considered to be due to micro-deformation and acceleration of the measurement position with some movement of eyeball muscles, arrector pili muscles and muscles corrugator supercilii. Microvibrations of small amplitude were also detected.