Development and Design of Portable Sleep Electroencephalogram Monitoring System / 生物医学工程学杂志

The growing rate of public health problem for increasing number of people afflicted with poor sleep quality suggests the importance of developing portable sleep electroencephalogram (EEG) monitoring systems. The system could record the overnight EEG signal, classify sleep stages automatically, and grade the sleep quality. We in our laboratory collected the signals in an easy way using a single channel with three electrodes which were placed in frontal position in case of the electrode drop-off during sleep. For a test, either silver disc electrodes or disposable medical electrocardiographic electrodes were used. Sleep EEG recorded by the two types of electrodes was compared to each other so as to find out which type was more suitable. Two algorithms were used for sleep EEG processing, i. e. amplitude-integrated EEG (aEEG) algorithm and sample entropy algorithm. Results showed that both algorithms could perform sleep stage classification and quality evaluation automatically. The present designed system could be used to monitor overnight sleep and provide quantitative evaluation.

Mathematical model of bursting spike train and its spectrum features / 生物医学工程学杂志

Bursting is an important firing mode of neurons. To propose a stochastic model of bursting spike train, the interspike interval (ISI) characteristics of single-spiking train and bursting spike train were analyzed and compared. In contrast with the exponential distribution of ISI in single-spiking train, normal distribution is supposed to be the ISI model of bursting spike train. Simulated neural spike trains were produced to investigate the spectrum features of the ISI model. The results showed that: (1) bursting spike train with normally distributed ISI held a low-pass spectrum while the spectrum of single-spiking train was flat; (2) the coefficient of variation of ISI in bursting train decided the bandwidth of its low-pass spectrum. Then neural activities from anesthetized rodent were used to check the validity of the model. 10 simultaneously recorded bursting spike trains and 10 single-spiking trains were selected during anesthesia and after pure-oxygen-washout period respectively. The spectrograms of these neural spike trains were analyzed and the results were matched with our mathematical model. It is believed that the bursting spike train model established in this paper will help to theoretically study the statistical characters of neural spike train and to add mathematical foundation in neural coding schemes.

An overview of the studies on combined electric and acoustic stimulation of auditory system / 生物医学工程学杂志

This paper discusses the technology of combined electric and acoustic stimulation (EAS) of the auditory system, which is a new therapy for the patients suffering from severe to profound high- and mid-frequency hearing loss but still having their low-frequency hearing. EAS uses hearing aid and cochlear implant technology together in the same ear. The hearing aid acoustically amplifies at low-frequencies, while the cochlear implant electrically stimulates at mid- and high-frequencies. The inner ear processes acoustic and electric stimuli simultaneously. This technique can provide substantial benefit in speech understanding for individuals with severe high-frequency hearing loss and can maintain their residual lower-frequency acoustic hearing. The study of EAS would significantly enhance the conventional cochlear implant therapy and benefit the patients afflicted with severe to profound hearing loss.

Advances in the study of virtual channels of cochlear implant / 生物医学工程学杂志

This paper discusses virtual channels of cochlear implant, which is produced by simultaneous or sequential activation of adjacent cochlear implant electrodes. Virtual channels create and transfer more available spectral pitch information with the limited number of fixed electrodes, which can be recognized as pitch percepts intermediate to those produced by each electrode separately. This technique not only utilizes the interaction of electrodes but also increases the number of place-pitch steps available to cochlear implant listeners. Virtual channels could be used to realize speech recognition in noisy environment, in enjoying music, and in understanding Chinese language. The study of virtual channels would significantly enhance the traditional cochlear implant therapy and benefit people suffering severe to profound hearing loss.

Study on the effect of spectral details encoding in speech processing on Mandarin recognition for cochlear implants users with speech maskers / 生物医学工程学杂志

The modern multi-channel cochlear implant devices produce good speech recognition scores in quiet. However, the ability of most implant users to understand speech with the speech maskers remains quite poor. The goal of this study is to investigate the effect of spectral details encoding in speech processing on Mandarin recognition based on various acoustic models. The improvement of the strategies that encoded spectral details was observed for speech recognition with speech maskers. We also proposed the implementation methods to improve the strategy and stimulate further investigation.

The application of amplitude-integrated EEG in the cerebral function monitoring of neonates / 生物医学工程学杂志

Amplitude-integrated electroencephalogram (aEEG) which is a simplified form of standard EEG has been increasingly used in neonates. The aEEG method is easy to apply and to interpret and the simplicity of the method makes it feasible for "round the clock" recording. The present paper briefly introduces the signal acquisition, data analysis and clinical applications of aEEG. Then we propose a number of possible research directions in light of the domestic research in this field, in the future.

Development of the technique for measuring soft tissue balance in knee replacement / 生物医学工程学杂志

Osteoarthritis is one of the most common joint diseases in the world, and the prevalence rate of osteoarthritis increases with the increase of age. Artificial knee replacement surgery has become one of the major measures to treat the severe pathological changes in the knee. The bone mechanical axis realigning and the soft tissue balance are the two key problems in the artificial knee arthroplasty. In this paper is introduced the development of the technique for measuring the soft tissue balance in knee replacement. And it is concluded that such technique would be continuosly improved in light of the development in the sensor technique and computer aided surgery technique. The soft tissue balance in knee arthroplasty can prolong the life of the artificial knee.

Estimation of Percentage of Electrogastrogram Slow Wave Rhythm / 航天医学与医学工程

Objective To improve the estimation and the percentage of electrogastrogram(EGG)slow wave rhythm with power spectrum estimation and calculation rule set.Methods Chirp Z-transformation was introduced for estimation power spectrum of EGG,which can obtain both high frequency resolution and accurate estimation of power;while the power proportion of main frequency components in each segment was used to substitute for conventional method in time domain.Results The variance of proposed method was about one-eighth of that of conventional method.Incorporating the power proportion of main frequency components,the proposed method gave better results especially for those EGG signals in which abnormal frequencies appeared frequently.Conclusion As compared with the conventional method,the proposed method is less affected by segmentation process in estimating the percentage of EGG slow wave rhythm,which may promote future clinical applications.

Comparison of the clinic results of speech processing strategies and latest advances on cochlear implant / 生物医学工程学杂志

Cochlear implant (CI) is a neural prosthetic device used to provide the sensation of sound to those who are profoundly deaf by delivering electrical stimulus to auditory nerve directly . It is becoming one of the main research frontiers in the area of otology and rehabilitation engineering . This symposium proposes an introduction about the new achievements of cochlear implant research , which consists of the following parts: the structure of CI, new speech processing strategies, comparison of the clinical results of speech processing strategies and the hotspots of the research.