We studied the brain activity (alpha and beta rhythms) with various motor imagery tasks for improvement of BCI usability using 14 EEG electrodes in five healthy subjects. For this purpose, we estimated two-class and four-class classification accuracy on the EEG signals with four motor imagery tasks derived from each type motor imagery (three classical motor imagery and one proposed mental strategy) tasks using t-test and SVM. The proposed mental strategy was imagery writing Kanji (Japanese characters). It has the possibility of both sensorimotor cortex and the visual cortex activation. Therefore, we expected to extract the distinct activity different from the activation with classical motor imagery tasks. In the two-class classification results, the classification accuracy was 73.7% on average in all combination of derived motor imagery task. Moreover, we demonstrated that four-class classification accuracy was 40.1% and the proposed task had possibility of the visual cortex activation dominantly. In experimental results, we proposed the new way for improvement of BCI application usability.
In this paper, Tube-shaped neural probe which has 8 recording areas and 3 optical emitting points using with optogenetics technique for neural circuit analysis has been developed. Outer diameter of tube is 360 µm, the recording areas and the optical emitting points arranged in a depth direction. The optical emitting points make it possible to stimulate neurons in various depth areas respectively. We demonstrated the recording and stimulating of neurons in vivo experiment. As the result, the probe got light induced neural activities at all the optical emitting points.
The auditory steady state response (ASSR) is elicited by repetitive presentation of auditory stimuli. Recently, the ASSR is used in EEG-based Brain-Computer Interface (BCI) paradigm. In this study, we have demonstrated efficacy of the Non-Harmonic Analysis (NHA) compared with the Discrete Fourier Transform (DFT) for ASSR-based BCI communication. The NHA is not much influenced by the analysis window length.
In social communication, Emotions are very important, and it has human intellectual activities and deep relations. And recent developments in noninvasive neuroimaging technologies have allowed for research on brain function. In this study, we investigated a potential of classification of listener's emotions using brain activity. Brain activity was measured using near-infrared spectroscopy (NIRS). We determined the classification of emotions (calm, anger, sadness and happiness). . As a results, accuracy was about 85%. So, the results suggested the potential for discriminating multiple emotions on a communication system using brain activity.
Fatigue behavior of polymethyl methacrylate (PMMA) was studied by using polymer electrostatic actuator connected with polymer specimen. A concentrated force was applied at the notch tip introduced at the side of the specimen when the actuator moved in a circumferential direction. The fatigue test was performed under resonant frequency and two specimens broke down by cyclic loading. The decrease in stiffness of the specimen by crack generating and progressing resulted in the deflection of the specimen and stoppage of the actuator's drive by misalignment of the comb-electrode.
Thermal conductivity λ of gases was measured by a steady state method using a microbridge-type MEMS sensor fabricated on a Si substrate. The sensor consisted of a hot wire with two adjacent thermocouples (TCs) on the surface of a SiO2 microbridge. Due to the small heat capacity of the microbridge, the temperature after heating increased much faster to a saturated vale ΔT than the onset time of natural convection, enabling the ΔT to be used for steady-state analysis. In moving gases, the difference of the ΔT between the upstream and the downstream TCs was proportionally increased with the flow velocity. In static gases, this difference intrinsically became zero, and the heat flow QP from the hot wire to base SiO2/Si pad areas was calculated using the input heating power Q to yield a constant ΔT for a set of gases with known λ. Once QP was obtained, the λ of unknown gases was found to be easily estimated with errors of less than 1% by measuring the Q to yield the same ΔT.