We have been developing a new pH measurement device by integrated pH-sensitive field-effect transistor (pH-FET) sensor into microfluidic device made from polydimethylsiloxane (PDMS). The device has many advantages such as small size, short response time, low consumption of sample solution, and internal transparency. In the previous report, we calibrated the device and measured around the neutral pH range then the device showed low measurement error. Though the measurement of pH with wide range eagerly desired, the device has not adapted for acidic or alkalic range yet. In this paper, we investigated the expansion of the linear range on the pH measurement device. The device showed high linearity in the range of pH 1 to 10. The correlation factor of the linear approximation of six standard solutions was 0.9985. The measurement error of these standard solutions was -0.0083±0.085. The device would be applied for many fields soon.

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In this study, we investigated histological evaluation of the titanium mesh electrode that was used for a transcutaneous communication system using intrabody communication . The internal communication unit wearing the titanium mesh electrodes were placed on the internal wall of thoracic cavity, and after 4 weeks, the explanted titanium mesh electrodes were prepared using hematoxylin and eosin stain, and investigated by light microscopy. From the results, the porosities of the titanium mesh electrode were filled with connective tissue and inflammatory cells. Occasionally macrophages or foreign body giant cells were observed, mostly lying on one side of the titanium fibers. Stress inside the titanium mesh electrode by movement of the internal communication unit would cause the inflammatory response and it would retard healing tissue inside the titanium mesh electrode.

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Experiments were conducted to investigate dissection ability and lifetime of spark electrodes as water jet generator. Performance of generator was evaluated pressure measurement with piezoelectric pressure transducer. 0.3 mm diameter Piano wire and 400-power diluted saline was used as opposite electrode and reactor of underwater discharge, respectively. Present experiments tried to explain on following: Relationship between counts of spark and pressure of jet with 3.5 mm of electrode gap, and pressure and measuring position with electrode after 50-75 counts of spark. Pressure was almost stable with 3.5 mm of gap until 80 counts. Hence, we can estimate that dissection ability of jet can be kept in the range of 40-180 counts. In relationship between pressure and measuring position, measured pressure at 2 mm from nozzle tip was higher than at nearer position. We anticipate that multistep jet was produced, and pressure is higher at an interaction point of several jets.

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The purpose of this study is development a blood collection assistant system for accident prevention. In the previous studies, a vein detection system by using absorbance of the hemoglobin and a needle puncture system by using the peak detection of puncture force and blood detection by electrode were developed and integrated. In this study, needle posture control following to arm posture was performed by using posture markers. As the results, the error of position adjustment was acceptable range. However the control of angle and direction was desired the improvement.

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As evaluation of disease progression or prediction of prognosis of patients with polycystic kidney disease (PKD), measurement of total kidney volume (TKV) has widely been accepted clinically. To establish automatic TKV measuring method with accuracy in PKD, we developed a segmentation algorithm of renal region. The coronal section of MRI T1 weighted images were used for the present study to capture the irregular boundary of polycystic kidney which often contacts with liver due to nephromegaly. Since biphasic luminance value of cysts and renal parenchyma was distributed, the GraphCut algorithm was utilized to discriminate renal region from the other organs. Then, the likelihood of pixels in foreground and background were calculated using Gaussian Mixture Model (GMM), and the GraphCut was performed. Segmentation results were evaluated by precision and recall, and compared with the method of the previous studies applying the region growing method and the level set method. The proposed procedure indicated high recall and precision compared to the previous studies.

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To suppress the scattering of light in a transillumination image, a new imaging technique using time-reverse technique with phase conjugate light has been reported. We have proposed the possibility of biological transillumination imaging using digital phase conjugate light generated with a spatial light modulator. In experiment, we attempted to restore the incident light image from the light passed through a scattering layer. This result indicates that the incident light can be restored by the digital phase conjugate light.

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For the diagnosis of postprandial hyperlipidemia, it is necessary to measure the temporal change of the serum triglyceride level by sampling the blood frequently. To solve this problem, we have developed an optical technique to evaluate the scattering property of the blood serum noninvasively. The scattering coefficient can be measured by the spatially resolved measurement of backscattered light with the diffusion approximation for light propagation. However, this approximation is not necessarily valid for the blood. In this study, we can estimate the scattering coefficient accurately even with the human blood (μ_a =0.5 /mm).

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In three-dimensional (3D) optical imaging of a living body with near-infrared light, image deterioration caused by scattering effect is a fundamental and serious problem. To solve this problem, we have newly developed a technique to reconstruct a CT image from tranillumination images with scattering suppression. In an experiment, the effectiveness of the developed technique was verified. The cause of the reconstruction error was found to be not from the technique itself but from the artefact of the experiment.

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The depth-dependent point spread function (PSF) is useful to improve the transillumination image blurred by the strong scattering in body tissue. We have proposed a technique to estimate the depth of an absorber by the PSF convolution of the images in different wavelengths. To evaluate the effectiveness of this technique, experiments were conducted. An absorber was placed at 2 mm depth in a scattering medium with 40 mm thickness. The proposed technique was applied to the images at 760 nm and 800 nm wavelengths. A correlation peak was observed near the given depth of the absorber. In these analyses, the feasibility of the proposed technique was verified.

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Sleep disordered breathing (SDB) has been identified as mortality risk factor in patients with cardiovascular disease. Although the severity of SDB is quantified primarily by the apnea-hypopnea index (AHI), the average number of apneas and hypopneas per hour of sleep, it is not clear whether the AHI is a reliable index to evaluate an increased mortality risk associated with SDB in cardiovascular disease patients. To address this problem, we analyzed polysomnogram (PSG) data including nasal flow and pulse oximetry (SpO2) level signals, and studied the association between characteristics of the PSG data and mortality in cardiovascular disease patients (n=112) with central sleep apnea due to Cheyne-Stokes breathing pattern. Compared to airflow-related parameters such as AHI, SpO2 level-related parameters, such as cumulative time rate with desaturation episodes, was stronger predictors of all-cause mortality. This result suggests that characteristics of SpO2 level drop related with SDB provide more important information to predict the mortality risk in cardiovascular disease patients than conventional AHI.

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Recently, falling accidents become serious problem by population ageing in Japan. 40 percent of elderly parsons who was taken to hospital are limited daily life by hospitalization. "Foot trajectory" is a most common case of falling accident. The reason is that elderly persons can’t recognize height of the foot in walking. For this reason, having them recognize height of the foot is valid for fall prevention. Besides, raising high the foot can prevent muscle weakness. In this study, we discuss a method of detecting height of the foot by acceleration sensors of smartphone. In addition, we place a smartphone around the wrist as useful body site. We experiment whether time waveform of acceleration can distinguish three walking patterns. (Three walking patterns are "Natural", "High step", "Long step".) The result showed that the time waveform can distinguish three walking patterns by amplitude and instantaneous value of "foot flat".

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This paper proposes a premium service for elderly people suffering from dementia. The service does not require new infrastructure, and is accessed by commonly available smartphones. One of the key advantages of this system is that it uses a very small sensor and low energy Bluetooth (BLE) technology which makes it both small and energy efficient. An application installed on smartphones will allow for city dwelling dementia sufferers to be tracked for the purpose of assisting them. The authors conducted a social experiment in Aichi Prefecture, Obu City (Japan) on November 29 (10AM to 11AM), 2014. There were forty participants who searched for sensor carrying elderly people suffering from dementia. The results of this social experiment confirm that this technology will help to find elderly people with dementia, and also provided some additional findings as well: 1) During times of rainfall, the detection range of the sensor decreased from 10m to 5m 2) detection from the rear had more narrow coverage that from the front, because of the interference of the human body blocking the transmitted signal, and 3) then the smartphone was operated within an automobile, it could not reliably catch the transmissions from the sensor.

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Posterior parietal cortex (PPC) is considered related to the formation of intention. The intention specifies the goal of a movement and the type of a movement. It has been reported in [Wang et al., PLOS ONE, 2011] that EEG signals extracted from PPC can be used to decode intended movement direction before actual movement. However, visual cue was used for users in the experiment. This raises a doubt about visual evoked potential (VEP) mixed into extracted EEG signals. It is not clear whether the extracted EEG signals were related to intentions. In this study, we conducted not only an experiment with visual cue but also an experiment with tactile cue. EEG components that could be related to PPC were extracted by using independent component analysis. Event-related potential (ERP) waveforms similar to the ones reported by Wang et al. were observed in the experiment with visual cue. On the other hand, ERP waveforms obtained in the experiment with tactile cue were totally different from the one with visual cue. These results suggest that VEP was included in the EEG signals extracted from PPC in the experiment with visual cue.

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The auditory mismatch negativity (MMN) is a component of event-related potential (ERP) that corresponds to a response to an odd sound stimulus among a sequence of uniform stimuli. Auditory MMN is considered as an index of automatic context-dependent information processing and auditory sensory memory, and previous clinical studies reported deficit of MMN in schizophrenia patients. To further understand the difference in auditory signal processing between healthy controls and schizophrenia patients, we utilized the EEG/MEG data analysis tool of SPM8, the generalized functional neuroimaging software, to localize cortical sources for the auditory MMN response. The advantage of using SPM8 in the analysis of MMN-ERP is that the reconstructed sources are represented in the normalized brain coordinates and thus it is available to statistically compare the volumetric cortical activities between participants. This paper describes how to process EEG data that were measured from conventional commercial system (Biosemi .bdf file) in the SPM8 to extract MMN responses, localize regional brain activities, and perform voxel-based statistical analysis between participant groups.

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In this study, we estimated the propagation configuration of epileptiform discharges in the ictal period from electrocorticogram of intractable epilepsy. We calculated the average value of the top 1% of the maximum cross correlation values of each channel-to-channel of the electrocorticogram. In the early stages of seizure, the value was rapidly rising when epileptiform discharges propagated throughout the brain. However, it was rapidly reduced in about 10 seconds despite the epileptiform activities continued, that is, the epileptiform activities were independently going on in each part of the brain. In the seizure termination, it increased again. The result indicates that each part of the brain synchronized towards the seizure termination. The results of the connectivity analysis show that the propagation configuration differed greatly between the onset of seizure and at the seizure termination.

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The steady-state visual evoked potential (SSVEP) is used for input signals of brain computer interfaces (BCIs). The SSVEP is generated by flushing visual stimulus. There are two types of stimulus for SSVEP. One is flushing visual stimuli and the other is flipping checkerboard patterns. In comparison with flushing visual stimulus, flipping checkerboard patterns have two advantages. Firstly, flipping checkerboard patterns activate SSVEP with weak energy of light. Secondary, there are little difference of SSVEP's features by each persons.
However, there are few studies described relationship between SSVEP and property of flipping checkerboard patterns. In this study, I pay my attention to the size of the grid in the checkerboard and the length on the side in the checkerboard.
As results, we obtained strongest power of SSVEP when the size of the grid in the checkerboard is 0.14 [cm] and the length on the side in checkerboard is 4.5 [cm]. In these experiments, distance between the checkerboard and subjects' eye is 60 [cm]. From these results, there are suitable size of the grid and length on the side in checkerboard.

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Recently, many researches on brain science have been reported. However, brain function related to decision-making have not been well-known. The purpose of this study is to reveal the brain function related to decision-making by EEG. We analyze EEG data by time-frequency analysis called ERD / ERS.
In this paper, we investigate EEG during the period of preparation to exercise press-button movements. We perform two tasks over 6 subjects. One task called the No-Go-Cue experiment. Subjects press a button when Direction-Cue is shown. The other task called the Go-Cue experiment. Subjects are shown Direction-Cue in monitor and prepare movements until Go-Cue is presented. Subjects press a button when Go-Cue is sounded. Direction-Cue is shown the direction of press-button by right or left arrow. Go-Cue by beep sound is shown timing to start press-button movements. We forcus on power of alpha band (8-12Hz). As results, two features were observed. 1) ERS occur when Direction-Cue showed. 2) ERD have occurred in the term between Direction-Cue and Go-Cue. First feature is estimated a response of direction-making related to movements. Second feature is estimated a response of movement planning.

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Recently, various brain function have been elucidated. However, the function related to decision making of movements is not clear.Therefore, we have examined relation between EEG signals and movement. Movement-related cortial potential (MRCP) is one of EEG signals related to movements. The MRCP in self-pace movements is properly understood. However, the MRCP in the other movements is not understood. The aim of this paper is to get finding of the MRCP in the experiment using Direction-Cue and Go-Cue. Direction-Cue is shown by right and left arrow on display. Go-Cue is shown by beep tone.This study focus on preliminary step of movements.
As results, we got two features over the 6 subjects. Firstly, negative potential be observed approximately 1 second after presenting Direction-Cue. Secondly, spike wave on bipolar be observed after presenting Go-Cue.

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We have developed an unsupervised multi-class classification algorithm of Steady-State Visual Evoked Potential (SSVEP)-based-BCI. Our previously proposed algorithm detects the frequency that gives maximum peak-to-baseline amplitude of the spectrum power among the frequency bands corresponding to the flicker light stimuli at the three electrodes arranged in occipital area, and majority voting among these electrodes determines the final output of the classifier. To further increase the accuracy, we examined whether (1) a feature that incorporates the peak-to-baseline amplitude of the spectrum power at the harmonic frequencies of the flicker frequency in addition to those at the fundamental frequency, and/or (2) a winner-take-all fashion of classification algorithm (classification based on the feature at a single electrode showing the maximum peak-to-baseline amplitude among three electrodes), could improve the accuracy of the classifier. The best accuracy (79.2%, N=32) was obtained when we incorporated the peak-to-baseline amplitude at the first and the second harmonics into features and selected the frequency at which the peak-to-baseline amplitude showed the largest value among the stimuli frequencies and electrodes. With this improved feature selection and classification algorithm, we could significantly improve the accuracy of the classifier compared to our previous algorithm (68.8%, p<0.001).

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To study relationship between surgical incision of bladder outlet and urine flow dynamics, a model of intra-urethral shape with BOO and the post-surgical models, incised at 6 o'clock or 5 and 7 o'clock direction of the bladder outlet, were generated. For each model, internal flow during micturition was calculated. Then the intra-urethral flow was visualized and transition of fluid energy was calculated. Then by difference between methods of incision for bladder outlet, changes in urine flow states have different property. And also amount of loss of energy were different by location in the urethra. Different changes in the shape of the urethra between models of two methods made different influences to urine flow dynamics. Therefore it is suggested that mechanism of beneficial change in urine transport efficiency would be different depend on how to change shapes of urethra.

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Fresh porcine spinal cords (N = 5) were obtained at a local abattoir, and intact nerve roots were excised using a surgical scalpel and fine forceps with a special caution. In total, 77 fiber bundles with a dimension of 30 mm in length and 0.5 mm in diameter were isolated from the excised nerve roots. By conducting a series of uniaxial stretching tests at three different velocities, 0.1, 1, and 10 mm/s, we revealed that mechanical properties of fiber bundles were relatively insensitive to strain rates under such a sub-impulsive loading condition. On average, elastic moduli, linear portion of stress-strain curve, resulted in 3.8, 3.3, and 4.5 MPa for 0.1, 1, and 10 mm/s, respectively. In addition, strain at failure was found to be almost constant, ∼0.15, irrespective of a 100-fold increase in the applied loading rate, while axial strains were distributed non-uniformly along fiber direction.

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The purpose of this study is to develop a system for measuring muscle hardness using an ultrasound imaging device. The system was applied to measuring muscle hardness before and after stretching. An ultrasound probe holder that has three force sensors was constructed. The holder could measure the force of the probe on the skin while acquiring an ultrasound image. Two images were obtained with and without a compression force of 1 kgf. Subjects were instructed to stand on a stretching board. Stretching was performed three times, and images were obtained again. The thickness of the muscle was measured from the image, and the strain was calculated. The Young's modulus of the muscle was calculated from the stress and strain. The Young's modulus decreased after stretching. It was concluded that the developed system could be applied to measuring muscle hardness.

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A human tongue can be deformed largely owing to the incompressibility of muscle fascicles. A tongue consists of muscle fascicles and muscle activations cause large deformations of a tongue such as protrusion and licking. Physics-based simulations of tongue deformation using mathematical models are useful to find out the mechanisms of oral cavity functions. The purpose of this study is to simulate large deformations of a tongue by using the muscle fascicle models. The authors propose a muscle fascicle model which generates contraction force and deforms with preserving its volume. The muscle fascicle interacts with other fascicles to restrain overlap of their occupying volume. A tongue muscle model is constructed by arranging some muscle fascicle models. In the simulation experiment, contraction forces were applied to each muscle fascicle model and simulated contraction of tongue muscle. As the result of simulations, the muscle model contracted in response to the value of input with preserving its volume and deformations of tongue muscle could be represented by interaction between each muscle fascicles.

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This study presents the effect on walking of improvement in standing posture of healthy young students. Most of them do not have a habit of playing sports or walking in their daily life. After long periods of computer work or sitting on a chair, they complained of lower back pain and a stiff neck. They have weak abdominal and back muscles and non-supple hip, knee joint movement. They have a habit to walk with a heavy bag on one side and also their posture is affected by the head being tilted forward every day due to prolonged smartphone use. They themselves explore the factors of their individual unbalanced standing posture, and in order to understand how to make correct posture, they do muscle strengthening, and movement to improve strength and flexibility of the joints for three months. After this period, most of their standing posture improved, and also their walking balance improved. Before this exercise, their walking balances were out of 1/f fluctuation, which is a stable index of human body. After this exercise, their muscle mass increased due to a diet of higher protein and reduced fat and carbohydrates. Then their walking balances were close to 1/f fluctuation. Their standing posture and walking balance improved after changing their daily life style. It is important to get good standing posture and walking balance while young students for preventive medicine.

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We have proposed a method to manipulate a thin catheter (less than 0.5 mm in diameter) using acoustic radiation force to achieve treatment in the human body. In this paper, we discuss the theory of acoustic radiation force acting on the catheter from basis of experimental results, which are the ratio of estimated forces from acoustic pressure and actually bending force on the catheter calculated by cantilever theory. The results show that the ratio versus ka (product of wavenumber k and radius of the catheter a) has minimum points, and it suggests that there is an optimal acoustical frequency for manipulating the thin catheter.

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Autoregressive (AR) models have been used in heart rate variability (HRV) analysis. In the conventional AR model, a Gaussian noise with a homogeneous variance are assumed to be the driving stochastic force. If this assumption is reasonable for the observed HRV time series, the HRV dynamics is fully characterized by its power spectrum. However, reasonability of the assumption has not been systematically examined. To address this problem, we studied variance heterogeneity, called heteroscedasticity, of HRV using a generalized autoregressive conditional heteroscedasticity (GARCH) model. In this study, we analyzed 24 hour HRV time series measured in healthy subjects (n = 122) and in congestive heart failure (CHF) patients (n = 108), and estimate the parameters of the GARCH model from the observed time series. In both healthy and CHF groups, variance heterogeneity of the HRV time series was observed. Furthermore, we found a statistically significant difference on the estimated parameters of the GARCH model between healthy and CHF groups.

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The study presented here relates a tissue hardness (stiffness) measurement system, or more precisely for example, external labor transducer for monitoring of gravidae, including possible cases of fetal and maternal combined signal transducer. As a theory of measurement, suction cup is applied on subject body surface where the tissue hardness thereon or shallow depth, is to be measured. Unlike conventional “pushing” type measurement, our method is to apply negative pressure (sucking) thereon by suction cup. Response of the body surface to this negative pressure is measured for external labor for example. The advantage of this method is that the suction cup can hold it on body surface for itself, to allow belt-less labor (and fetal signal by the way) transducer, for easier operation.

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Urine is excreted at core temperature, 37 °C. Noncontact matrix temperature sensors simultaneously measuring the temperature of 16 areas were utilized to estimate the volume of urine in a toilet. Two temperature sensors were installed face to face under the toilet seat. In this preliminary study, water at 37 °C was dropped at various flow volumes, flow rates and drop positions.The integrated value of the 3/2 power of the temperature change for the 16 areas increased with the flow volume and remained constant with the increase in flow rate.

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Hyperthermia is one of cancer thermotherapies and there are several ways of heating. Among them, we have researched the Soft-heating method. In this method, we insert heating elements and apply a high frequency magnetic field to them by an excitation coil placed outside the body. With this method, we can cure tumors without overheating them.
We have applied the LC booster method to the excitation system, which makes it possible to generate a high current by utilizing the magnetic coupling between two coils. In this method, we connect a primary coil with a power source, and use the excitation coil as a secondary coil. This makes the load on a power source lower and enables the excitation coil to move freely. This study presents the design of a primary coil and examines the effect of the change in the relative distance between the two coils on the excitation current.

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The purpose of this study is to develop a wearable sized sweating rate meter. It is known that thermal sweating rate reflects deep body temperature and dehydration. Therefore, continuous sweat measurement with a small sudorometer is expected to contribute to the prevention of heat stroke. The distinctive features of developed device are wearable size, eliminated capsules and packaged functional elements such as an air pump and two humidity sensors on it. Sweating rate is determined by the conventional method that uses the humidity difference between ambient air and the air moistened by sweat. The fabricated device has functional elements and flow channel on flexible substrate. It was evaluated that the device could quantify the sweating rate within precision of 15 percent by measuring water in place of sweat. Also, increases in thermal sweating rate on forearm after passive heat stress were successfully measured with the developed device in all subjects.

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The depression of skin barrier function causes that it is easy to take into various chemical substances, so that it causes allergy. It is very useful to quantitatively evaluate the state of the skin barrier in domains such as dermatology, nursing science and the cosmetics development. Therefore the authors developed a portable impedance measuring device for evaluation of skin barrier function. This device can be operated by single hand because of compact and lightweight. After the head contacts the skin, the parameters, such as susceptance B and admittance Y in two kinds of frequencies, are measured and calculated in approximately three seconds. The equivalent impedance circuitry, that represents some kinds of keratin-removing skins by tape stripping method, consisted of parallel RC circuits. Using these circuits the precision of this device were confirmed that the errors were less than several percent. The correlation with these parameters and TEWL (transepidermal water loss), and the regression expressions for estimation of TEWL were examined. We found that an index of corneum barrier about the same as TEWL.

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