Yoshiaki Saitoh

Development of a Communication Support Device Controlled by Eye Movements and Voluntary Eye Blink

A communication interface controlled by eye movements and voluntary eye blink has been developed for disabled individuals who have motor paralysis and therefore cannot speak. Horizontal and vertical electro-oculograms were measured using two surface electrodes referring to an earlobe electrode. Four directional cursor movements and one selection were realized by logically combining the detected two channel signals. Virtual input experiments were conducted on a virtual screen keyboard. Its usability and accuracy were improved using our proposed method.

Development of communication supporting device controlled by eye movements and voluntary eye blink

A communication interface controlled by eye movements and voluntary eye blink has been developed for disabled individuals who have motor paralysis and therefore cannot speak. Horizontal and vertical electro-oculograms were measured using two surface electrodes referring to an earlobe electrode. Four directional cursor movements and one selection were realized by logically combining the detected two channel signals. Virtual input experiments were conducted on a virtual screen keyboard. Its usability and accuracy were improved using our proposed method.

A re-entrant type resonant cavity applicator for deep-seated hyperthermia treatment

A heating method using a re-entrant-type resonant cavity applicator for deep-seated hyperthermia treatment and its computer simulation are described. In this heating method, a human body is placed in the inner gap of the cavity and is heated by standing-wave electromagnetic fields. From the results of computer simulations using a disk phantom, it is shown that a deep and local tumor may be heated effectively without generating any hot spots or edge effects as in the case of an RF capacitive heating method.<<ETX>>

Analysis of a hyperthermic treatment using a reentrant resonant cavity applicator for a heterogeneous model with blood flow

Hyperthermic treatment using a reentrant resonant cavity applicator is investigated. By solving time-dependent electromagnetic field-heat transfer equations for a heterogeneous model, temperature distributions in various organs are obtained. Calculated results show that it is indispensable to consider the blood flow to predict accurate temperature distributions during a hyperthermic treatment. Also, it is found that the necessity of measuring the electrical and thermal properties of the abdominal fat accurately as well as optimizing the heating system to avoid the concentration of electromagnetic energy around the abdominal fat-muscle interface.

Optimal Pacemaker Sensing with Respect to Amplitude and Slew Rate of Intracardiac Electrograms: Theoretical Analysis by Computer Simulation

The optimal amplitude and slew rate of intracardiac electrograms for pacemaker sensing Here examined on a theoretical basis by computer simulation. The simulation was based on the concept that it is the voltage at the position of the pacing electrode in an electrical field of a moving electrical dipole. By changing the distance between the electrode and the myocardium and the moving velocity of the electrical dipole, simulated ECGs with arbitrary amplitudes and slew rates were generated by the computer and fed to a bandpass filter. This filter was equivalent to those assembled in some models of permanent pacemakers and had a center pass‐band frequency of 50 Hz and a Q of 1.0. The outputs of the filter were measured. The results showed that, for pacemaker sensing, simulated intracardiac electrograms with high amplitude should have high slew rates and those with low amplitudes should have low slew rates, although the absolute values depend on the characteristics of the bandpass filter and the sensing threshold of the pacemaker.

A muscle fatigue index based on the relationship between preceding background activity, and myotatic reflex response (MRR)

An index of muscular fatigue was developed using the myotatic reflex response (MRR). The MRR of masseter muscles is evoked by periodical mechanical chin tapping during clenching. The MRR waveform is composed of somewhat synchronized action potentials of muscle fibers. The authors estimate the change of the MRR waveform due to fatigue using the instantaneous frequency pattern (IFP) with the Hilbert transform. As a result, the features of IFP were different from the monotonic changes that have been observed by the conventional fatigue indices. That is, a plateau IFP was observed ahead of considerable fatigue, whereas the IFP showed a monopeak pattern during the other phase of an exercise. Also, the relationship between the preceding background mean power frequency and the instantaneous frequency around the first part of the MRR waveform was nonlinear during the whole process of fatigue. These features may allow the authors to estimate the degree of fatigue at each time instant.<<ETX>>

Analysis and development of a radio-frequency rectangular resonant cavity applicator with multiple antennas for a hyperthermic treatment

An analysis of a resonant cavity applicator for radio-frequency hyperthermic treatment has been carried out. A rectangular cavity applicator with multiple antennas is found to be suitable to heat deep-seated cancer tumors. The experimental results with a dielectric phantom have shown the possibility of selective heating for deep-seated tumors and the validity of the calculations.

Artifact elimination using fuzzy rule based adaptive nonlinear filter

Myoelectric (ME) signals during dynamic movement suffer from artifact noise caused by mechanical friction between electrodes and the skin. The frequency components of artifact noise are similar to those of ME signals. Thus it is difficult to reject artifact noise using linear filters. the authors have proposed a nonlinear artifact elimination method that consists of an inverse autoregressive (AR) filter, a nonlinear filter, and the AR filter. To improve the performance they installed adaptive filters so as to track time-varying signals. However, fuzzy rules were employed for fine control of the nonlinear parameter. As a result, the authors achieved a better artifact elimination performance. The fuzzy rule based adaptive nonlinear filter will be useful in sport, science and rehabilitation.<<ETX>>

Implantable defibrillator with high-output pacing function after defibrillation

An experimental implantable defibrillator with a temporary pacing function was developed. The pacing function was activated after defibrillation to work as a high-output ventricular-demand pacemaker. The developed system was tested in animal experiments involving anesthesized and mechanically ventilated mongrel dogs. In the animal experiments, fibrillation was electrically induced, and the automatic defibrillation and pacing function were confirmed. After defibrillation, it was possible to continue the fixed-rate pacing for more than three minutes. >

Isochronal map of chest wall vibration with cardiokymography

Mapping analysis of cardiokymography is helpful in clarifying the relationship between vibratory pattern and recording sites, but needs a highly stable recording technique. We have therefore studied the stability of recording cardiokymograms, and present here a new method for creating stable maps which enables diagnosis of chest-wall vibration abnormalities. Cardiokymograms were recorded on 16 points of the chest wall located at regular intervals horizontally and vertically. The time interval between a R-wave peak of the electrocardiograms and an E-point of the cardiokymograms were measured for all the 16 records. Isochronal maps in 23 healthy subjects were classified into four types. The map of a patient with myocardial infarction was quite different from any one of the four normal patterns and seemed to show a paradoxical movement of the chest wall.