Core temperature, the temperature of humans' brain and organs, is one of the most important signs of the human body. Abnormalities can be detected in early time by monitoring the fluctuation of core temperature. Nowadays core thermometer using the Zero-Heat-Flux method is widely used in clinical settings, but it was still unwearable during its considerable power consumption.In order to noninvasively measure core temperature under ambulatory conditions, we have been developing a wearable core thermometer based on the Zero-Heat-Flux method. From the results obtained by simultaneous measurement using a commercial deep-body thermometer (CTM-205, TERUMO), it was confirmed that the prototype had nearly the same accuracy, and its power consumption was reduced to about 1/4 since the aluminum shell and the surrounding skin surface were covered by insulating materials. It could be considered to use in the future for protecting people from heatstroke and other heat diseases in their daily life.

Although the pulse transit time is generally used for blood pressure estimation without a cuff, a method of estimating blood pressure only from photoplethysmography based on the relationship between pulse waveform and blood pressure has been studied. This can resolve the inconvenience such as measurement with an electrocardiogram and allow more continuous and simpler blood pressure measurement.Previous studies have proposed methods of machine learning by extracting features such as wave height and time difference.At this time, the waveform of the pulse wave is different, because the blood vessel shape changes by the contact condition between the sensor and the fingertip.However, the previous studies have not been sufficiently verified how the contact condition of the sensor affects the Reflected Green Light and Infrared Photoplethysmography.In this paper, we analyzed the effect of the contact condition of the sensor on the feature quantity used for the blood pressure estimation.

We aim to develop a thermal uroflowmeter which employs non-contact thermal sensors. This thermosensitive uroflowmeter is able to install in an existing toilet. However, the sensitivity of the heat-sensitive surface of the thermosensitive uroflowmeter is not uniform. In this study, we propose a correction method to make the sensitivity of the heat sensitive surface uniform.

This work was partly supported by JSPS KAKENHI Grant Number JP19141662.

Daily monitoring of core-body temperature and its rhythm (biological clock) is important for understanding the ovulation cycle of women, early detection of various diseases and health promotion. However, it is difficult to measure them easily and accurately. One reliable measurement is continuous measurement of rectal temperature, but it is not practical in daily life. Ingestible core-body temperature sensors have been released overseas. However, it is dangerous due to use of a button battery. Therefore, we have proposed an ingestible thermometer that stores energy by gastric acid power generation. This approach without button batteries realizes safe, compact, low environmental load, long-term storage, and inexpensive devices. Here, we report on prototyping the device for proof of concept, and on an in-vivo experiment. As a result, the inner body temperature of a dog was successfully measured by taking it. This result suggests the feasibility of a safe and secure ingestible thermometer.

The detection of fever and disability of body temperature regulation are needed in medical and care facilities. However, this measurement is burden using commercially available devices. To resolve this drawback, we investigated a method for estimating the body temperature in bed using a sensor unit over the bed-mattress which has a resistance-sensitive pressure sensor, a thermistor, and an insulating material. After detecting the contact of subject's body surface and the sensor unit by the pressure sensor, the body temperature can be estimated from the increase rate of the thermistor output for 30 seconds. From the results of simultaneous recordings by the bed-installed system and a conventional axillary thermometer in two healthy subjects (22 yrs.), the body temperature could be successfully obtained within the error range of 0.4 degrees and the additional investigation in elderly is also showing comparable accuracy, demonstrating the usefulness for the early diagnosis of fever.

Body temperature is important biological information in early detection of heat stroke and physical condition management for a spinal cord injury person. It is common to use body surface temperature to measure body temperature. However, the body surface temperature changes depending on the environmental temperature and the state of blood flow. On the other hand, the deep body temperature can accurately grasp the subject's body temperature regardless of the environmental temperature or the state of blood flow. We have developed a wearable deep body temperature monitor using the dual heat flow method. In this study, the measurement accuracy was verified using the developed monitor and a commercially available deep body thermometer using the zero-heat-flow method. As a result of the experiment, it became clear that the developed monitor has higher measurement accuracy than the commercially available deep body temperature monitor when the lower environmental temperature.

The purpose of this study is to investigate the calibration method for calculating core body temperature using ear canal temperature. The calibration method based on the dual-heat-flux was derived from the surface temperature in ear canal and temperature difference between space and surface in ear canal and the ambient temperature of near ear. Firstly, vitro experiment to investigate the accuracy of the calibration method was performed using a cylindrical black body furnace just like the inner ear. Secondly, vivo experiment to validate the calibration method for calculating of core body temperature while performing 3 ambient temperatures (18, 28, 38 °C) condition in 10 subjects. The result showed that difference between calculated black body temperature and measured black body temperature as a reference was -0.003 ± 0.035 °C. Vivo experiment, the same tendencies were observed; very small difference between calculated core body temperature and tympanic temperature.

Functional optical coherence tomography (fOCT) is a method to three-dimensionally visualize neural activation and brain function with micro-scale spatial resolution. The fOCT has been applied to functional imaging in retinal research and is expected for clinical application in retinal diseases. However, there are few reports where fOCT was applied to the cortex. This is because the cortical tissue is high scattering medium as compared with retinal tissue and stable detection of fOCT signal is difficult due to physiological noises, e.g. heartbeat and respiration. In this study, we realized high-accurate fOCT by employing Fourier imaging, which analyzes temporal modulation of fOCT signal elicited by periodic stimulation and extracts only signal component at the stimulus frequency. The proposed method was demonstrated by three-dimensional visualization of neural activation in rat somatosensory cortex (barrel cortex) and functional structure (orientation column) in cat early visual cortex.

A communication support device using functional Near-infrared-spectroscopy (fNIRS) for Amyotrophic Lateral Sclerosis(ALS) patients has been studied. For example, a difference between brain signals in response to a cognitive task such as mental arithmetic and those in the resting state was used to distinguish Yes and No. However, the accuracy was not high enough to be used in practical and an improvement of task paradigm has been desired. In this study, we developed a new cognitive task utilizing a feature of auditory attention. After fNIRS measurements in 16 healthy subjects, we found a significant difference mainly in the left frontal pole between a music attention condition and a speech attention condition. Moreover, by using support vector machine, we achieved about 80 % of the identification rate in average among four subjects. These result showed that our task has a potential to improve the accuracy of the communication device for ALS patients.

[Background] In Raman microspectroscopy, non-labeled molecular tissue imaging is achieved. However, it is usually difficult to mathematically decompose observed spectra into the signals from individual molecules, even when we simply distinguish lipids from proteins.[Objective] In this study, we aimed to achieve Raman spectroscopic measurement to obtain lipid-only distribution using delipidation technique for sample preconditioning.[Methods] Molecular vibrational images of a 20-μm frozen section of porcine peripheral nerve tissue were measured using spontaneous Raman microspectroscopy, before and after delipidation using ethanol solutions, and the distribution of ethanol soluble fraction was obtained by image subtraction. [Results] The subtracted spectral image did not contain 1000cm^-1 peak of Phenylalanine, which is typical in protein spectra, but showed Raman shifts typically found in lipids, such as 1305cm^-1, 1450cm^-1 and 1650cm^-1.[Conclusions] Our approach achieved lipid-only non-labeled imaging of biological samples. This method can be used with the conventional mathematical technique of spectral decomposition.

Diffuse correlation spectroscopy (DCS) is an optical technique to noninvasively measure the blood flow of deeper tissues such as muscle layers. This study aimed to capture blood flow changes with finer time resolution by improving the sampling frequency of DCS measurement from conventional rate of 1 Hz to 100 Hz. We acquired blood flow data from the forearm of a healthy participant during rest and dynamic handgrip exercise. The DCS signals measured at 100 Hz detected the pulsatile blood flow fluctuations during both of rest and exercise states, possibly depending on the phase of the pulse wave and the change of the intramuscular pressure. The peak-to-peak amplitudes of the blood flow increased during exercise relative to rest, suggesting the exercise-related increase of the blood supply to the muscle. These results suggested that DCS measurements with high temporal resolution contribute to more accurately determine the hemodynamics of tissues.

Heart rate measurement is stressful for the subject because most of the measuring devices need to bring sensors into contact with body. In addition, remote heart rate measurement is necessary in such case as Judo, in which wearing a rigid object is prohibited. Therefore, we are conducting research to accurately measure the heart rate of a moving human from several meters. In this study, we photographed the palm of right hand with a web camera (Logicool Qcam Pro 9000) and examined about the measurement of the heart rate by the change of the pixel value. The palm was fixed on a stand so as not to move, and the distance between the camera and the palm was about 5 cm. In order to increase accuracy, an arithmetic mean of 480 × 480 pixels was taken. As a result, periodic fluctuations synchronized with the heartbeat was observed in the G component.

Cardiac pulse measurement from video images is promising, because of non-invasive access of physiological parameters with an unconstraint manner. Though averaged heartbeats measurements have been demonstrated by many researchers by using this method called photoplethysmography imaging (PPG imaging), next problem should be achieving instantaneous pulse interval measurement for non-invasive pulse rate variability. In this study, PPG imaging waveform from uncompressed and compressed video formats were compared for assuming remote site monitoring. Facial video images from six subjects were discussed. The results show that a non-negligible high-frequency noise component were superimposed on PPG waveform from compressed videos by H.264 standard. A usually used H.264 parameter Constant Rate Factor (CRF) 23 also gave PPG waveform with noises. H.264 videos by not greater than CRF value three gave equivalent waveform with waveform from uncompressed video. Our findings indicate that video compression mode should be discussed for precise measurement of PPG imaging.

The aim of this study is to examine the variability of the pulse rate (PR) derived from imaging photoplethysmogram (iPPG) and the face skin temperature using the developed prototype system with a built-in RGB and thermal camera module during cold pressure task (10 °C). PR was detected from the peak frequency of iPPG, which is produced by the variability of green component of 30 Hz sampled RGB image on the forehead area. Nose area temperature was calculated as the average of 50 pixels among the face thermal image. The results in 5 subjects showed that mean blood pressure and PR were increased 5.22 mmHg and 6.44 bpm. The nose skin temperature was decreased 0.95 °C. The standard error of each indices were 1.80 mmHg, 2.42 bpm, 0.29 °C, respectively. In conclusion, these findings suggest that the developed prototype system might be practical measurement for stress monitoring.

Respiratory rate can be measured in a variety of ways such as nasal temperature, breath sounds, and chest and abdominal movements. However, many instruments used in clinical practice today are of the type that attach sensors to the body. Therefore, when a screening test for sleep apnea syndrome (SAS) is performed at home, for example, the subject may not sleep well because the sensor is attached, and there is a concern that no symptoms appear. Further, especially in the case of a child, there is a possibility that the sensor or the wiring is disconnected or entangled due to turning over. Therefore, in this research, we aim to develop a device that can measure the respiratory rate of patients without contact. This time, using an infrared camera, we measured the temperature change of the body surface or blanket due to respiration, and examined whether the respiration rate could be measured.

To improve QOL of chronic dialysis patients, period of dialysis treatment should be as short as possible. Effect of dialysis is evaluated by blood tests before and after treatment. Because the efficacy cannot be evaluated until the end of dialysis, development of real-time monitoring system of multi-components in dialysate drainage is required to determine appropriate dialysis period.In this study, we tried to predict concentration of urea, uric acid, and creatinine in each aqueous single component solution using FT-IR spectrometer. From the results of the multiple regression analysis with all combinations of ten commercially available LED wavelength, we determined the most appropriate wavelengths combination in order to realize an easy-to-use optical monitoring system using LED. Accuracy of the concentration prediction was evaluated by the standard error of prediction, and the correlation coefficient between actual and predicted concentration. As a result, we confirmed high accuracy in three components concentration prediction.

Injuries of peripheral nerves during surgery should be avoided to prevent a poor prognosis. Nevertheless, it is difficult to recognize peripheral nerves. Therefore, a system to identify nerves during surgery is required. We had developed a coherent Raman scattering rigid endoscope to visualize nerves without staining. By using coherent Raman scattering, substances are visualized selectively without staining based on information of molecular vibration. We had successfully visualized nerves in the rabbit prostate fascia, but it had been necessary to reduce the present exposure time of several minutes to several seconds. Last year we reported that improving the signal-to-noise ratio using deep learning shortens the exposure time. In the conference, we show the results of ensemble learning to achieve significantly higher accuracy comparing with the previous learning results.

An objective biomarker has not been established for attention deficit hyperactive disorder (ADHD). In a previous study, the hypoactivation pattern was found in the right prefrontal cortex during a Go/Nogo task in ADHD children compared with a control group, using functional Near-infrared spectroscopy(fNIRS). The Go/Nogo task is often used for measuring prefrontal activity, and is expected to be applied to examination of adult ADHD. However, it was suggested that the Go/Nogo task for children is too easy for adults to induce significant brain activity. Therefore, we improved the Go/Nogo task to measure prefrontal activation in adults, aiming at development of application for adult ADHD. In our fNIRS experiment, thirty healthy adults underwent the improved Go/Nogo task with three stimuli and a conventional Go/Nogo task with two stimuli. The statistical analysis revealed that the improved Go/Nogo task induced more significant activation in the right middle frontal gyrus than the conventional task.

Photo-aging caused by ultraviolet not only accelerates aging of the skin, but also predisposes to skin cancer precursor symptoms. To evaluate photo-aging, various modalities are being used, such as histopathological diagnosis, optical coherence tomography, ultrasound examination (B-mode imaging). However, they have disadvantages in terms of invasiveness, penetration depth and tissue specificity, respectively. To overcome these defects, photoacoustic imaging (PAI), a novel modality, was used in this work. This modality can portray differences of tissue characteristics non-invasively. To verify the feasibility of quantitative skin aging evaluation with photoacoustic technique, signals from sectioned human skin (cheek and buttock; females from 28 to 95 years old) were measured with photoacoustic microscopy. The effects of photo-aging progress on the signal intensity were investigated. The results demonstrated that the PA signal from the dermis increases with aging progress. These analyses demonstrate the feasibility of quantitative skin aging evaluation with a PA imaging system.

Endogenous gas analysis such as gastric and intestinal gas potentially offers a fast and convenient noninvasive diagnostic method for a variety of diseases. However, the sampling and sample preparation step are error prone and must be optimized to ensure the reliability of the results. For this Purpose, a miniature photoacoustic system was developed to perform gas sampling using a smart endoscope. Endogenous gases generally contain a variety of thousands of possible volatile organic compounds. An array of modulated laser diodes and its controller were developed and coupled via an optical fiber bundle a photoacoustic sensor head, because interferences of other compounds can be reduced by using several laser wavelengths.A mixture of CO2 and N2 gases was measured using a triple-wavelength optical source (450, 1420, 1540 nm) to detect the various compounds. In this report, we describe details of the structure of the proposed system and its capabilities.

We have developed an optical technique to measure the turbidity of random media such as animal tissue and blood. In this technique, we can estimate the reduced scattering coefficient us'of the scattering medium from the reflectance R(d) as a function of the source-detector distance d. It was applied to the noninvasive evaluation of the blood turbidity in the subcutaneous vein in an adult forearm. The validity of this technique was verified with the blood vessel with abut 5 mm diameter. Here, we attempted to apply this technique to much thinner blood vessel such as the capillaries. We constructed the model phantom of the capillary and measured the reflectance R(d) using a CCD camera. The estimated reduced scattering coefficient us'was lower than the given value. However, the change in the estimated us'corresponding to that in the given us'was confirmed. This result suggested the applicability of the proposed technique to human capillaries.

The blood vessel network can be visualized in the near-infrared transillumination imaging. This technique is safe and convenient, but the image is seriously blurred by the light scattering in the body tissue. If we can estimate the depth of the blood vessels under the skin surface, we can eliminate the blur by the deconvolution with the point spread function (PSF) of the blur. In addition, we can reconstruct the 3D trans-body image using the estimated depth. First, we generated many blurred images in different conditions using the PSF derived from the diffusion approximation of transport equation. In the analysis of these images, we found that the Jackson contrast of an absorber image and the spread of the blur are the major parameters which sensitively vary with the depth of an absorber. Then, we construct the database which can output the depth when we provide the contrast and the spread of the blur. After the confirmation in simulation, we applied this technique to the real data in experiment. The accuracy of the depth estimation was satisfactory. Using the estimated depth, we could reconstruct the 3D structure, as well.

The near-infrared (NIR) light has relatively low attenuation through animal tissue, and has been used for transillumination imaging of a human body. It is a safe and convenient technique in medical applications, but the image is seriously blurred by the strong light scattering. When we see the blurred image, we can imagine the blurless image from our experience. Therefore, if we can train the neural network with enough number of training data, we can obtain the blurless image through the trained neural network. The validity of this idea was examined using the network for deep learning. For the network we used the fully convolutional network (FCN) of the U-net. The performance of the neural network is largely dependent on the number of training data. We generated the blurred image of blood vessel by the convolution of a point spread function which we originally derived from the diffusion approximation of the transport equation. The validity of the proposed technique was confirmed after the training with 5000 blurred images of different shapes, depths and diameters of the blood vessel. By increasing the training data to 7500 images,the performance was significantly improved.

Using the near-infrared (NIR) light within the wavelength range of the biological window, we can visualize the subcutaneous blood vessel and the hemoglobin distribution. If we can arrange the directions of light source and image sensor appropriately, we can expect to map the blood vessel or the hemoglobin distribution all over our body. To realize this goal, we introduced a human-cooperating robot-arm system to our NIR transillumination system. First, we attach a stereoscopic camera on the robot-arm and measure the 3 dimensional coordinates of the irregular surface shape of a subject. Then we replace the stereoscopic camera by the NIR light source and CMOS camera for transillumination imaging. The robot arm places the light source and the camera at the appropriate position and orientation, and captures transillumination images. It repeats the same operation while changing the position to scan all the surface of the subject. The images are stored to reconstruct the 3 dimensional transillumination image of the subject body. In a preliminary study, the operation of the first part was confirmed with a human adult arm.

Using near-infrared (NIR) light, we can visualize the internal structure of an animal body. With relatively thin part of human adult body such as a hand and a foot, we can obtain transillumination images. The distribution of hemoglobin density is typically imaged in the NIR transillumination images. This technique has been commonly used with a still image or an off-line moving image, because it generally requires long exposure time and large image processing capacity. To make the real-time operation possible, we have developed a hardware oriented system with a high sensitivity camera. It can take moving image at 3 different wavelengths (730, 810, 850 nm) in the speed of 10 fps. Using this system, we can visualize the temporal change of the spatial distribution of tissue oxygen saturation. The validity of this system was confirmed in the transillumination imaging of oxygenation change in a hand by stopping the blood circulation at the wrist. In the application to different kinds of physical and psychological stimuli, the usefulness of the developed system was verified.

Using near-infrared (NIR) light, we have developed a noninvasive technique to measure the blood turbidity caused by the lipid in blood plasma. This technique is based on the diffusion approximation of transport equation. It has been known that this approximation is valid for the scattering-dominant condition such as human tissue around the blood vessel. However, the applicability to human blood has been in doubt, because the scattering and absorption coefficients of blood are in an equivalent order in the NIR wavelengths. In addition, the estimated scattering coefficient is inevitably contaminated by the strong scattering from the surrounding tissue around the blood vessel. To solve these problems, we made the Monte Carlo (MC) simulation of photon propagation in random medium. The validity of the simulation was confirmed in comparison with the simulation by the finite element method (FEM). In the MC simulation, the applicability of our proposed technique to human blood was verified. It was shown in simulation that we can effectively suppress the large influence from the peripheral tissue on the estimation of scattering coefficient of blood in the subcutaneous blood vessel.

We have developed a technique to estimate the scattering coefficient of a turbid medium from the spatial distribution of backscattered light on the surface of the medium. Using this technique with a nearinfrared light, we can expect to evaluate the turbidity of the blood plasma noninvasively. The developed technique is based on the diffusion approximation of the transport equation. This approximation is valid in the scattering dominant case such as the general body tissue, but the validity is in doubt in the blood case. To examine the validity of this technique, we have conducted the experiment. A model phantom was made which simulates the body tissue and the blood. The light with 800 nm wavelength is directed on the phantom surface, and the intensity of the backscattered light was measured at the same surface by a photomultiplier tube. A mechanical chopper and a lock-in amplifier were used to increase the signal to noise ratio of the measurement. The estimated scattering coefficient followed well with the given change in turbidity both in the tissue and blood cases. For practical use, we need to improve the sensitivity of the scattering estimation more.

NIRS instrument for brain function measurement has been used as an auxiliary diagnostic device for mental diseases. Stationary NIRS systems are high-performance, but very expensive, and it takes time to prepare for inspection of mounting the optical fiber probe on the head. Therefore, we have developed a headband-type NIRS device for a simple and inexpensive measurement of brain activities. In this study, we developed a new Android Tablet software for controlling NIRS devices and displaying waveforms, and measured the oxygen saturation (SpO2) in arterial blood in the cerebral cortex. The developed application included functions for controlling the NIRS device, drawing measured waveforms, saving and comparing waveforms, and visually presenting verbal fluency tasks. In addition, using the light source wavelength used for the pulse oximeter, the simultaneous measurement of the NIRS signal and the arterial blood oxygen saturation in the cerebral cortex were examined experimentally.

Working memory has slave systems called the phonological loop and the visual space sketch pad. In sequential memory tasks, in which working memory should play a role, memory performance is reduced by shortening the intervals between memory item presentations. To clarify how the working memory concerns the sequential memory, we recorded magnetoencephalograms from 29 subjects performing two sequential memory tasks with either long or short intervals (hereafter, slow and fast conditions, respectively). Amplitude of beta-band rhythm (14–29 Hz) was time-averaged during memory maintenance period. The averaged amplitude were compared between conditions in each 68 brain area. In inferior temporal gyrus (memory area) and lateral occipital cortex (visual area), the averaged amplitude of the fast condition was significantly larger than that of the slow condition. This result suggests that short interval of fast condition makes it difficult to recruit phonological loop, and recruits visual space sketch pad dominantly.

Recently, biomagnetic measurement has attracted attention. there are many high-sensitivity magnetometers for biomagnetic measurement. However, most are specialized for low-frequency minute signals such as magnetocardiography (10pT ~100Hz) and have not been developed for higher frequency. We focused on Optically-Pumped Atomic Magnetometer (OPAM) to measure high-frequency signals. OPAM is a sensor that utilizes the optical pumping phenomenon in which the valence spin is polarized when light of a specific wavelength is incident on an alkali metal atom. OPAM has traditionally been studied under precision fixing, vibration isolation and strict magnetic shielding. We developed OPAM measurement system that modularized optical system in order to improve the adaptability to the living body. In this study, we report that we applied PLL (Phase-Locked Loop) to OPAM module and achieved minimum resolution of 0.992~1.359 pT/Hz^1/2 for 20-450 kHz.

In this study, we conducted a study on tonometry using acoustic radiation pressure. We created a device using a parametric speaker, and thought that it would be possible to measure intraocular pressure by measuring the frequency of the surface vibration by applying acoustic radiation pressure to an object. In the measurement, the object was set to a water balloon, and the vibration of the surface was measurement by observing the reflection of an irradiated laser beam using a high-speed camera. And the data was subjected to Fourier transform to measure the eigenfrequency. Then the relationship between the eigenfrequency and the pressure in the water balloon was discussed.

We are working to visualize 3D human blood vessel using ultrasound for an active drug delivery. The purpose of this study is improving the structural analysis method of blood vessel network (BVN) of human liver by applying three-dimensional extension to investigate BVN deformation. For the structural analysis in a BVN, bifurcation points were extracted using point cloud. And for the extension, the connected part was clarified using the position of the probe recorded by a position sensor. In the proposed method, since more accurate structure of BVNs was obtained, a wider liver BVNs from the right lobe to the left lobe could be obtained, where the maximum total path length was about 1200 mm in the largest BVN. Furthermore, we evaluated the deformation of BVNs quantitatively under the specific conditions as changing the subject's posture or breathing state.

Ventriloquism effect is the illusion in which sound source localization is captured by concurrent visual information. Though recent studies suggest that audio-visual illusion is associated with cross-frequency coupling (CFC) at superior temporal area, the causal relationship between the ventriloquism effect and the CFC remains unclear. Here, we manipulated transcranial random noise stimulation (tRNS) to the superior temporal area of the participants, who were asked to indicate the direction of the perceived voice. The voice was presented from either of 21 speakers located from -30 to 30 degrees with/without the video of lip movement at 0 degree, where 0 degree indicates the front. During tRNS, the ventriloquism effect was reduced with the smaller localization error and standard deviation as compared with the sham condition. The results suggest that tRNS disturbs the CFC at the superior temporal area and that the ventriloquism effect is caused by the CFC.

In recent years, Brain-Computer Interface (BCI) has been catching much attention. EEG has been bringing remarkable results on the communication with those patients with ALS, locked-in syndrome and rehabilitation against patients with cerebrovascular disease. However, wet electrodes used on EEG set on the patient's head directly and it could cause mental dissatisfaction on him. A solution to this problem is to use pasteless dry electrodes but tend to have higher noise and costly. Fabricating a dry electrode of any shape in a short time at low cost by using an SLA type 3D printer with high spatial resolution, the purpose of the study is to measure EEG without conductive gel, and we consider appropriate electrode shape. Using the fabricated electrode, we measure the change of alpha-wave that predominates while the eyes are closed.

For early detection of the slight muscle injury, we present a sensing method based on electrical impedance distribution of musculoskeletal tissue. The system collects potential data for various excitation conditions by using multiple electrodes surrounding the target object and discriminates the muscle state by machine learning. We optimize the sensing efficiency by selecting excitation conditions based on the correlation analysis of the normal and injured muscle. We utilize the simulated data for optimizing the parameters of discriminator without using measurement data for the injured state. Furthermore, we propose an environment-invariant detection method by considering implementation error of the electrode position. We investigated the effective excitation conditions and discrimination ratio by using a musculoskeletal phantom for various injured conditions. As a result, it was found that the proposed system has 100 % discrimination ratio using 7 out of 120 excitation conditions and reduced measurement time from 38.4 s to 224 ms.

To develop a simple and accurate measurement technique of intramuscular fat, we present a new sensing method based on the change in the electrical impedance by muscle stretch. The system obtains the electrical gain characteristics of the muscle tissue for various stretch conditions, and identifies the parameters by fitting the transfer function of the equivalent circuit to the obtained data. Then, the amount of intramuscular fat is estimated by the multiple regression model using the parameters. For the feasibility evaluation, we investigated the estimation error by using a phantom that mimics the electromechanical properties of muscle and fat. As a result, we found that the proposed system is capable of estimating the fat amount with 2.7 % error. Because the estimation error of the sensing method without muscle stretch conditions was 5.6 %, the use of muscle stretch was found to be effective for reducing the estimation error.

There are needs for the development of continuous and long-term measurement techniques for heart condition of drivers, because traffic accidents caused by heart disease of drivers are prevented. Heartbeat is an index of heart condition. Typical heartbeat measuring devices hinder driving because the sensors are in contact with the body. On the other hand, the coupling capacitance electrode can be measured non-contact, there are few obstacles to driving. This system measures the heartbeat by using the characteristic that the coupling capacitance changes due to the deformation or displacement of the dielectric. Since the change in the coupling capacitance is very small, the change is amplified using a resonance circuit. There is a problem that the meaning of the output waveform is not clear. Therefore, we analyze the waveform in non-contact heartbeat measurement using coupled capacitive electrodes. As a result, it was found that the output waveform meant the heartbeat.

Heartbeat measurement using a Doppler radar is applied widely for vital signs monitoring in a home healthcare. However, when the Doppler radar measures chest surface movement containing both cardiac and breathing signals with body movement. Extracting cardiac information from superimposed signals is a remaining challenge. This paper proposes a novel method named the Convolutional Reconstructed- Singular Spectrum Analysis (CR-SSA). This algorithm includes two processes: a signal decomposition by singular spectrum analysis and a reconstruction by convolution with decomposed signal related cardiac information. This method was compared with a band-pass filter on a dataset of 134 samples with large noise from 212 samples collected from an experiment. As a result, the number of subjects with heart rate errors of less than 3 bpm and 5 bpm increased from 9 to 19 and 25 to 36, respectively. The results imply the potential to use for heartbeat estimation under respiration and body movement.

In recent years, traffic accidents due to health are increasing. So, continuously and long-term measurement technologies of heart rate and breathing are desired to develop for during driving. We are proposing a method to measure heart rate and respiration using a coupling capacitance electrode. In this study, we considered the measurable range and the directivity when the shape of electrode is changed. We compared the output amplitudes of the heartbeat signal at the changing the diameter of the electrode. As a result, it was found that there is a correlation between the diameter of the electrode and the measurable distance. In addition, we considered the electrode shape so that it can be control the capacitive coupling by surrounding the coupled capacitive electrode with ground electrodes. As a result, it was found that it is possible to have the directionality of sensitivity on the coupled capacitive electrodes.

In ablation treatment for atrial fibrillation, whole-heart mapping is used for estimating the excitation of cardiac tissue. However, verification of the estimation accuracy is insufficient. In this study, we constructed a simultaneous measurement system of optical measurement of membrane potential and electrode measurement of extracellular potential, and performed experiments using isolated rabbit heart. Using a cardiac support net, 15 Ag-AgCl electrodes were attached to the heart. Three high-speed cameras were located around the heart specimen at 120 degree intervals for optical measurement. Tachyarrhythmias were induced by electrical stimulation. Simultaneous measurement was done for 2 seconds by external trigger device. As a result, it was confirmed that the error of excitation passage timing in both measurements was about 2 ms. From the above results, it is considered that the constructed system realized simultaneous measurement, and this system can be used for verifying the accuracy of whole-heart mapping.

In the leg vein valve disorder makes deep vein thrombosis, sometimes pulmonary embolism. Therefore, we evaluated the character of the leg vein using bio-impedance. By Foster and the study of Schwan et al., the electric conductivity of the blood is known to be bigger than adipose tissue. The electric current can measure the change of the local blood volume and tissue structure by bio impedance method. The range of frequency of bio-impedance changes between 100~1000Hz. So we decide the 1kHz frequency for measuring of bio-impedance of leg. We attached an electrode on a great saphenous vein, to evaluate leg vein changed by the height of leg. When the change in bio-impedance by raising the leg, the bio-impedance of leg was lower than previous position.

Elderly with cardiac failure increase in nursing home. Especially, taking a bath sometimes poses a risk for subjects with chronic cardio- pulmonary disorders, due to the thermal effect and water pressure on his/her body. Therefore, we propose a new electrocardiogram (ECG) monitoring system with only floating on surface of hot water in bathtub to detect abnormal cardiac rhythm. The sensor unit has two electrodes, circuit for elimination of body motion artifact and signal amplification, and microprocessor with Wi-Fi module. Using the electrodes installed in the bottom of unit touching the water, the ECG signal can be obtained from the potential differences between two electrodes. The data is transfer to a cloud server through Wi-Fi and thus can be browsed using a web browser. In five healthy adults (22-years-old), the ECG signal could be successfully measured, showing the usefulness for supporting the bath in the nursing home.

During over-night measurements using capacitively coupled electrodes, the amplitudes of the observed signals were often influenced by perspiration. This study aims to employ the phenomenon as a method for assessing perspiration. As a preliminary stage, this study investigated a quantitative relationship between the amplitude of the signal and the quantity of the saline, which was used instead of sweat to increase reproducibility. For the same purpose, an ECG simulator was used. Several types of clothes, such as 100% cotton, were used as insulator. The results for different clothes showed similar piecewise-linear relationships, suggesting that this method could be the basic principle of perspiration assessment using capacitively coupled electrodes.

To elucidate the mechanisms underlying drug effects, it is crucial to measure local pharmacokinetics within organs. At clinical site, multiple drugs are simultaneously used for treatment of a variety of diseases. In this case, the pharmacokinetics would be complicated because of drug-drug interaction. To precisely determine the drug dynamics, it is necessary to develop a sensing system that can track different compounds in real-time. In this study, we utilized a diamond microsensor and established a dual-drug monitoring system based on electrochemical method. Initially we analyzed current-voltage properties of two antibiotics, vancomycin and ceftriaxone in PBS. Both drugs showed reduction currents in response to negative potential. Second, we analyzed PBS containing both antibiotics. From the current data, we constructed an analytical algorithm by machine learning method. This algorithm permitted us to quantify vancomycin and ceftriaxone simultaneously in real-time. The method described here would be valuable to optimize multi-drug therapeutic regimens.

In this study, we reported on a shear stress measurement sensor in MRI (Magnetic-resonance-imaging) by pressure transmission. Our sensor consists of the contact portion, the sensing portion, and connecting pipes. The contact portion was fabricated by pouring PDMS (polydimethylsiloxane) into a jig made with 3D printer. The sensing portion was assembled with an absolute pressure sensor, a jig made with 3D printer, and an O-ring for preventing fluid leakage, and was connected to the contact portion with Teflon connecting pipes. The pressure of the contact portion changed by the deformation of the fluid-filled part is transmitted to the sensing portion through the connecting pipes, and this pressure change was measured as shear stress. We evaluated the sensitivity of the x-axis and y-axis sensors. Then we took MRI images with and without fabricated sensor in MRI to confirm the compatibility with MRI.

The purpose of this study is to propose a novel method to estimate natural frequency using a myotonometer with the aid of a system identification technique. A myotonometer is an instrument that measures muscle hardness based on an indentation method. The myotonometer applies a mechanical rectangular pulse to an object and records the acceleration of the indenter. This method showed the dependency of the natural frequency on the rectangular pulse width. Our proposed method extracted the acceleration that was not affected by the rectangular pulse. The extracted acceleration was regarded as an output of a system from the mechanical pulse to the acceleration. The system was identified, and then the natural frequency was calculated. We applied the method to edtimate the natural frequency of a gel-like object mimicking human soft tissue. The proposed method provided a smaller standard deviation of the natural frequency than the built-in program of the myotonometer.

While force sensors usually use strain gauges, we use magnetic Hall effect sensors to get three dimensional unknown forces. In this study, we have three unknowns and nine of outputs. Therefore, this is an overdetermine problem with redundant outputs. The best method to calculate the unknowns was introduced.

In developing endovascular treatment devices, understanding their physical property is one of the most important points. We have been developed film-type sensor for force measurement, applied to the field of biomechanics. In previous study, contact pressure distributions between balloon catheter and model vessel were measured, and the contact pressures were significantly lower than balloon inflation pressure because vessel wall was soft and deformable. In this study, influence of elastic modulus of model vessel on the contact pressure was investigated. The film sensor was constructed by a couple of patterned electrodes and pressure-sensitive layer. Straight vessel models with 7mm diameter were fabricated by polyvinyl alcohol (PVA) hydrogel. The film-type sensor was inserted to the model vessel, and contact pressure between balloon and model vessel was measured. As a result, the contact pressures were significantly lower than the balloon inflation pressures, and related elastic modulus of model vessels.

The flexion of finger could be one cause of error on blood pressure (BP) derived from finger based on the volume-oscillometric method (VOM). We aimed to investigate the effect of fingers flexion on the BP derived from finger. In three healthy subjects, the experiment was conducted simultaneous BP measurement at the finger and arm during three finger bending conditions (angle: 0 to 10(A), 20 to 30(B), 40 to 50(C)). The set of three conditions was repeated twice. The standard deviation of the difference between the mean BP derived from finger using prototype system and mean BP measured by sphygmomanometer (HEM-907) as a reference: angle A was 11.96 mmHg, B was 6.95 mmHg, and C was 8.46 mmHg. The angle B is a natural flexion of the finger without artificial motion or strength. Therefore, the B might be suitable angle of finger for BP measurement based on the VOM.

The progress of the ultrasound diagnostic device enables to diagnose fetal diseases. It is reported that the postnatal disability can be prevented by treating these disease during fetal period. Though it is required to measure the fetus biological information after the treatment, the measurement is difficult because the fetus is inside the mother. In this study, we proposed a biological information measurement method based on pressure measurement by analyzing the ultrasound Doppler images of pressure sensing module containing microbubbles. Additionally, we evaluated the feasibility of the pressure measurement method by simulating a pressure sensing module being placed under pressure by changing the inner pressure of a tube enclosing microbubbles. The result shows that the number of pixels in the high brightness area increases linearly with the increase of the pressure in the range of 0 kPa to 20 kPa.