Aortic Valve Stenosis (AS) has been associated with aneurysm, and dissection of the ascending aorta. In this study, we tested the hypothesis that impinging jet blood flow due to AS is suggested to disrupt endothelial integrity, contributing to the formation of the aortic diseases. After cultured vascular endothelial cells (ECs) were exposed to impinging jet flow using a custom-made flow circuit, cell-cell junction proteins, VE-cadherin and PECAM-1 were fluorescently stained. As a result, detachment of ECs and a decrease in PECAM-1 expression were observed only in the area where higher wall shear stress and dynamic pressure exerted, while VE-cadherin expression was not changed. These results suggest that EC cell-cell adhesion, known to be important in endothelial integrity, is affected by the mechanical environment caused by impinging jet flow.

Therapeutic properties of mesenchymal stem cells (MSCs) are known to have close relations with the stemness, but micromechanical environment to make the stemness retain has not been established so far. On the other hand, MSCs in vivo are reported to localize near and/or on the blood vessels, which has us infer a hidden effect of curvature of the tubular scaffolds on functional modulation in MSCs. In this study, to reveal the curvature-dependent modulation in stemness of MSCs, behaviors of them were analyzed on curvature-graded tubular scaffold. MSCs were seeded on a tapered glass tube coated with fibronectin. MSCs were aligned in parallel to the tube axis in the region thinner than radius of 50 um, while at random in the region thicker than 50 um. Interestingly, MSCs tended to accumulate around the tip of tube, suggesting a potential sensitivity for the curved microenvironments.

Embryonic body (EB) formation has become a routine step in differentiation of stem cells. EB size influences the efficiency of differentiation induction. To induce differentiation with high reproducibility in mass-production, it's very important to exclude irregular EBs at an early stage. In this paper, we propose a system that cultivates many EBs at one time and predicts EBs quality by machine learning. EBs were cultured by TASCL, and time-lapse image of each well was took every 30 minutes. Then, we input 6 images up to 3 hours after seeding as one training data to the three-dimensional convolutional neural network (3DCNN) and predicted whether EBs were formed 1 day after seeding. As a result, the accuracy was 96.5% in the test data. Furthermore, we predicted EB diameter 3 days after seeding by inputting 12 images up to 6 hours after seeding into 3DCNN. As a result, the prediction error was ±7.1μm.

Cell culture requires scaffolds for cell adhesion and growth. In this study, effects of scaffold material surfaces having different cell adhesion on cell behavior were quantitatively evaluated. Effects of comb-shaped coating on cell migration and pattern width were analyzed by employing different scaffold materials. Hydroxyapatite (high biocompatibility and cell adhesion) and fluorinated diamond-like carbon (high biocompatibility and hydrophobicity) were employed as scaffold materials. Pattern widths (HA:FDLC) of 200 um:150 um, 150 um:200 um, 500 um:500 um, and 9 mm:9 mm were applied, and mouse fibroblasts (NIH-3T3) were incorporated. A medium containing 0.1% fetal calf serum was used for suppressing cell growth. A real-time cell culture observation system was employed for observing cell behavior, and time-lapse photography (photographed after every five minutes) was conducted for forty-eight hours. Results indicate that changing the pattern width or scaffold material causes variations in cell migration properties. The scaffold surface structure also affects cell migration.

This work describes the usefulness of nanofibers of natural materials as bio-inks for 3D Bio Printer. We prepared hydrogel sheets of alginate mixed with cellulose or silk nanofibers for cell culture. After culturing for several days, the proliferation rate of cells was analyzed by MTT assay. As a result, we confirmed that nanofibers would promote cell growth within alginate hydrogel. Next we fabricated 3D hydrogel structures using 3D Bio Printer with low concentration alginate solution mixed with nanofibers. We succeeded in fabricating 3D hydrogel structures with low concentration alginate solution mixed with nanofibers, however, were not able to fabricate these structures with only low concentration alginate solution. Thus, we concluded that these nanofibers would be suitable as the substrate for cell culture and the ingredient of bio-inks for 3D Bio Printer.

Endothelial cells form important barriers which play vital roles in the regulation of exchange of substances between the blood and surrounding tissues in many organs. In vitro models employing endothelial cell sheets may provide useful information on the formation and functioning of important in vivo barriers such as the blood brain barrier. In this study, we sought to investigate the influence of cell adhesion restriction on self-organization of endothelial cells into barrier layers and to evaluate their properties. Using microstructured mesh substrates (mesh line width: lessh than 5 micro meters, aperture size: more than 100 micro meters), we show that endothelial cells can self-organize into cell sheets with highly marked expression of VE-cadherin and improved barrier properties.

Closed culture system is required to prevent culture medium spill in gravity experiments such as centrifuge- and clinorotation- culture. Here, we have developed a special chamber made of PDMS (polydimethylsiloxane), a highly gas permeable material. This chamber is composed of PDMS lid and base on a coverslip. Specifically, unpolymerized PDMS was poured into the lid- and base-molds, and was cured at 60°C for 1 hour, then, the cured PDMS was removed from the molds. Next, the base and cover glasses (18 × 18 mm) were irradiated with an excimer lamp (EXCIMER: USHIO Inc.) for 4 minutes and the strong adhesion was achieved. We have already confirmed that cells were successfully cultured in this chamber without any medium spill, and are going to use this chamber to elucidate the mechanism of gravitational cell responses.

Bone marrow aspiration is a part of the procedure for bone marrow examination for blood disease tests. A bone marrow aspiration needle was punctured to lumbar bone and bone marrow fluid was collected using a syringe. Insufficient skills sometimes leads damage of surrounding tissues, however unskilled novices have to learn proper puncture force, timing and speed by OJT. For these reasons, training in a simulated environment for bone marrow aspiration is required. In this study, we developed a training system for bone marrow aspiration and verified whether the system promote the operator's proficiency. Our system shows optimal puncture force by visual feedback of puncture force's waveform during training. The system was tested by 10 non-medical professionals.

In pericardiocentesis, the heart with a cardiac tamponade is punctured from outside the body into the pericardial space.This is a technique to collect and drain pericardial effusion to release pressure on the heart.However, the pericardium and heart are not visible at the time of puncture, and the heart remains beating, so it is necessary to perform puncture with appropriate control of needle insertion without excessive puncture to the myocardium. It is a high technique.The purpose of this study is to develop a pericardial puncture training system that can accurately measure simulated pericardium penetration timing and puncture force and that can be used repeatedly. Pericardial puncture was performed on the simulated pericardium of the beating heart simulator to measure the puncture force.We report the use of the system by one cardiologist and the quantitative evaluation as a training device.

In the field of plastic surgery, delicate procedures for anastomosis of small nerves and blood vessels are required. To improve microsurgical technique, training in an environment simulating actual surgery is necessary, but there is no system with sufficient performance yet. We have developed an AR-based microsurgery training system that enables stereoscopic viewing of microsurgery procedures while watching a surgical image of a veteran doctor as a teacher image. To simultaneously solve the problem of low resolution and the problem of time delay between the actual procedure and the viewed video, a new input device using two cameras was developed. The developed system was evaluated by a plastic surgeon.

This study was designed to investigate association between certificate examination for biomedical engineering (class2) (MEc2) and national exams for clinical engineer (CE) and medical technologist (MT). We retrospectively collected 450 students entered in NUHW from 2011 to 2015. Odds ratio (OR) and 95% confidence intervals (CI) was calculated using logistic regression models. Receiver operating characteristic (ROC) curve was employed to identify the optimal cut-off values of MEc2 score in determination of risk to fail the national exams. Compared to first try passer of MEc2, re-try passer and failure were associated with increased risk to fail the CE exam ([OR:8.53,95%CI:2.82-25.81] and [OR:39.93,95%CI:12.27-129.95], respectively). Moreover, re-try passer and failure were associated with increased risk to fail the MT exam ([OR:9.29,95%CI:4.17-20.67] and [OR:14.82,95%CI:5.92-37.15], respectively). The optimal cut-off scores for MEc2 were 70 (to CE exam) and 75 (to MT exam). MEc2 is an effective predictor of risk to fail the national exams.

Poly(lactic acid)(PLA) is a typical biodegradable resin, which is decomposed into water and carbon dioxide by hydrolysis in the body. In recent years, 3D printers of the FFF (Fused Filament Fabrication) system have attracted attention for processing poly(lactic acid). It is known that the strength of a structure formed by an FFF 3D printer differs depending on the nozzle scanning direction. However, knowledge considering the decrease in strength due to immersion is not sufficient. The purpose of this study is to evaluate the strength of test pieces immersed in saline or ultra-pure water. The immersion periods were 30, 60 and 90 days. The strength of the test pieces was evaluated by a four-point bending test. The maximum bending stress of P. 30 days after immersion was significantly reduced when immersed in saline compared to the non-immersed test piece of preparation, but did not decrease with ultra-pure water.

In brain function measurement by NIRS, NIRS-SPM, which displays brain active region by obtaining correspondence between brain and head position, has been attention. However a magnetic sensor used to acquire head position is expensive, we propose an inexpensive head position measuring way by a 3D laser scanner (DAVID).A blue line laser is irradiated on three directions of 45 degrees left, front, and 45 degrees right of face, and the images are composited. Then, the coordinates of the four points (Nz, AL, AR, Cz) and of the twelve points below the NIRS probe are obtained with Autodesk 3ds Max. The measured inter-probe distance (30 mm) were compared with that measured by the caliper. The difference between them was 2.3 mm on average. The brain activity area for the behavior suppression task was over 9 mm square from fMRI measurement, thus this method is applicable to NIRS-SPM analysis.

Laser induced thermal therapy (LITT) is a new therapy for brain tumors based on optics and heat transfer.A heating region is determined by light propagation and heat transfer in LITT.Both physical phenomena can be represented by parabolic partial differential equation. A temperature distribution in living tissue can be predicted by solving the equation.A subject is to be carried heat away by blood flow in LITT. Generally speaking, it is known that increased blood perfusion decreases temperature in living tissue (JOMA 100.5-6 (1988): 655-667). It is easily assumed that laser irradiation is going to bring a localized temperature increasing. However, it is too difficult to grasp the temperature distribution in living tissue because of a lack of information about blood flow by localized heating, In this study, it is reported that a difference of the temperature distribution due to a difference of blood perfusion using opto-thermal numerical simulation.

A mathematical model of brain's physiological condition was constructed in consideration of the inter relation of intracranial pressure, cerebral blood flow, brain temperature, and cerebral metabolism. This model is necessary for designing and verifying the automatic control system of brain's physiological condition which is being developed to evolve the brain resuscitation.In this paper, the constructed model was analyzed using the almost normal parameters in order to verify the adequacy to use it as a substitute for patients. As the parameters used in this analysis were obtained from more than 10 papers and a few mechanisms of regulating brain's physiological condition were not considered yet in the model, the several analyzed values were inescapably different from the measured value in the previous papers. However the analysis result totally showed no contradiction from the viewpoint of anatomy and physiology. Therefore this model can qualitatively represent normal brain's physiological condition at least.

We often search for a specific target by sight from in many alternatives. According to Hick's law, the search time is logarithmically proportional to the number of alternatives. However, its mechanism has under clarified. We hypothesized that human gaze migration networks in visual search have small-world phenomena. Then, the searcher would be able to find the target in short time. In order to verify the hypothesis, firstly, we extracted tremors and saccades from gaze migration data of the visual search experiment. Using them, secondly, we designed several gaze-point-networks. When the ratio of tremors and saccades was close to that of the experiment, the gaze-point-network showed relatively large small-world characteristics from two network parameters; high clustering and short distance coefficients. A future work is to investigate whether the gaze migration model moves on the network in short time. To this end, the peripheral visual fields would be needed in the model.

A new Hill-type model of skeletal muscle referred to as the SL/ST model is proposedbased on recent physiological findings obtained from frog semitendinosus muscles. The model has two modes: a sliding filament mode (SL mode) and a stretch-evoked force enhancement mode (ST mode). Since the outline of the model has been published as a short note in Adv Biomed Eng. (2019), the detail is presented in the present report.

Reverse total shoulder arthroplasty (RTSA), which was introduced in 2014, is a new shoulder prosthesis. We investigated the joint reaction forces of the three usual types (Medial Glenoid/Medial Humerus, Lateral Glenoid/Medial Humerus, Medial Glenoid/ lateral Humerus). During a passive movement of scapular abduction, the highest joint reaction force was observed with the Medial Glenoid/Lateral Humerus model. Now we are investigating the forces during other active movements.

The mechanism underlying WPW syndrome features accessory conduction between the atrium and ventricle. We recently visualized the histological morphology of the accessory pathway using a three-dimensional image reconstruction technique. However, the morphological and electrophysiological details of an accessory pathway are unclear. Here, we performed computer simulations of anterograde and retrograde accessory pathway conduction using a simplified wall model. We investigated the relationships among the bundle size of the accessory pathway, intercellular conductivity, and accessory conduction. We found that increasing the intercellular conductivity of the atria and ventricle promotes such conduction. By contrast, we found that increasing intercellular conductivity of the accessory pathway prevents accessory conduction. Source-sink theory may explain the first points; an electrotonic effect may explain the second one. Our findings provide new insights into the morphological and electrophysiological details of the accessory pathway.

Since large number of variables and complex numerical expressions are included in biological function models, its simulation programs often include errors. To avoid such errors, usage of mathematical model described by description language such as CellML to generate simulation programs automatically is considered. Jacobian matrix is often used for model analysis such as bifurcation analysis and equilibrium point analysis. Jacobian matrix usually have many elements, which often leads to errors in its calculation program. To address this problem, we proposed a system that automatically generates Jacobian matrix calculation program by using a biological function model described by CellML. To visualize the dynamics of cell models, we propose a visualization method which displays Jacobian matrix elements as a heat map sequence. By the method, we realized that the relationships between model variables can be visualized efficiently.

Force velocity relation (FVR) is known to be one of the basic characteristics of the ventricular myocyte where the muscle contraction force decreases according to the increase in muscle shortening velocity. The left ventricle (LV) twists during contraction and untwists with sarcomere length (SL) change from isovolumic relaxation time (IVRT). Although the effect of the SL change on the hemodynamic is not clear, we can analyze the effect by using the mathematical model. In this study, we used a circulation model that can reproduce SL change during IVRT. The model consists of Negroni & Lascano2008 cardiac contraction model, blood vessel model, LV physical model, and SL model derived from reported data by Rodriguez. The results suggested that SL change during IVRT contributed in the shortening of IVRT by rapid decrease in force due to FVR.

Background: In acute heart failure (AHF), evaluation of cardiac pumping function, i.e., cardiac output curve (S), and stressed blood volume (V) is essential for hemodynamic management. However, these measurements require an invasive right heart catheterization. In this study, we developed a less invasive method which predicts S and V by using positive end-expiratory pressure (PEEP).Methods: Circulation equilibrium framework determines hemodynamics by S and V. In four mongrel dogs, we measured central venous pressure and cardiac output under various PEEP conditions. We predicted S and V from these hemodynamic variables with or without AHF by using circulatory equilibrium framework.Results: Predicted S (R2 = 0.86, RMSE 5.5 ml/min/kg, PE 32%) and V (R2 = 0.63, RMSE 5.3 ml/kg, PE 25%) were matched well with those measured regardless of AHF.Conclusion: Our proposed method could predict S and V less invasively and may contribute to the safety management of AHF.

Bicuspid aortic valve disease is a common congenital valvular disease. There are several variations in valve morphology and its relationship with ascending aortic dilation is not clear. In this study, we newly developed a pulsatile circulatory system to investigate flow in ascending aorta using 4D-MRI. The simulator consists of the silicone-made left ventricle, aortic valve chamber, aortic arch, compliance tank, and reservoir. The aortic valve model was fabricated using bovine aorta and pericardium and installed in the valve chamber. Pulsatile pressure and flow were pneumatically generated and controlled by peripheral resistive unit. A tricuspid aortic valve model was investigated by 4D-MRI. In the ascending aorta, straight flow was observed in early-systole and physiological clockwise-twisted flow was observed in late-systole respectively. Therefore, the pulsatile circulatory system developed in this study can be useful for revealing the relationship between bicuspid valve morphology and flow pattern in ascending aorta.

Cardiac chambers are often represented by a time-varying elastance model in hemodynamic simulation. However, myocardium also has viscosity in the real world. To evaluate the effects of viscosity of myocardium on hemodynamics, a computational models of cardiovascular system was developed with a time-varying visco-elastance chamber model based on the Kelvin-Voigt viscoelasticity model and a modified 3-element Windkessel vascular model. To simulate a failed heart, the left ventricular end-systolic elastance (Ees) was varied from 3.0 to 1.5 mmHg/ml. An addition of viscosity on the left ventricular elasticity increased the stressed blood volume (SBV) to maintain mean arterial pressure and decreased the left ventricular ejection fraction (LVEF). The impacts of viscosity on SBV and LVEF in the failed heart with Ees of 1.5 mmHg/ml were larger than those in the normal heart with Ees of 3.0 mmHg/ml. The left ventricular viscosity may largely affect hemodynamics of heart failure.

Various types of biosignal time series often exhibit long-range correlation. Since the autocorrelation function has a one-to-one relation with the power spectrum, the long-range correlated behavior can be evaluated using the power spectrum. In the long-range correlated time series, the estimated power spectrum takes the form of S(f)~f^(-beta), where f is as the frequency. Thus, the long-range correlation is characterized by the scaling index beta. In addition to such long-range correlated behavior, crossover phenomena of two regions having different scaling indices have been observed in biosignal time series. In this study, we propose a general mathematical model to reproduce the long-range correlation and the crossover phenomenon. In our approach, the autoregressive fractional integral moving average (ARFIMA) (1, d, 0) model is modified using a fractional difference operator. In our presentation, we will discuss the mathematical properties of our model and its application to biosignal time series analysis.

Much kind different dialyzer are used appropriately by the state of the patient.The one of performance evaluations about the dialyzer is a creatinine clearance(CL).CL depends on the effective film area.This research has been performed a verification experiment using 2 kinds of effective film areas (NV-15U and NV-13UL : TORAY INDUCTRIES INC.) about CL.The results of CL are 182.5[mL/min] at NV-15U and 180.0[mL/min] at NV-13UL.The price is the difference in the 1%.However, NV-15U is 1.2 times NV-13UL about the effective film area. Then, we thought there are other factors about the relation between the CL and the effective film area.The CL is influence of the flow velocity as well as the effective film area in other joint research.Therefore, it is suggested that the result of this verification experiment depends on influence by the flow velocity.

For valvular insufficiency associated with annulo aortic ectasia, a new technique has been devised to repair the annulus dilatation by suturing the commissures of the valve. This study aimed to develop a finite element analysis methodology for the technique.The hyperelastic Ogden model was applied for constructing a finite element model of the aortic root, and the material properties of ePTFE suture were obtained by uniaxial tensile test. A suture model was placed around the commissure from the outside of the aortic wall. We compared two procedures; 1) shrink each commissure in the radial direction of the aorta, and 2) shrink commissures circumferentially.As a result, the incomplete closure area decreased 0.181 cm2 to 0.005 cm2 in the 1), and to 0.001 cm2 in the 2). In this study, we constructed a basic methodology of finite element analysis that can reproduce and quantitatively evaluate the annuloplasty procedures.

The left anterior descending coronary artery (LAD) compliance and hemodynamics changes after coronary artery bypass grafting and percutaneous coronary intervention are unclear. We have been developing a mock circulatory system for reproducing coronary hemodynamics including microcirculation. In this study, we newly developed the controlling mechanism of coronary vascular resistance. The simulator consists of roller pomp, silicone-made LAD and microvascular model, check valve and compliance tubing. We developed the linear motion mechanism for the reproduction of fluctuation of peripheral coronary artery resistance following ventricular contraction. As a result of the synchronization of two types of actuators, we obtained physiological coronary hemodynamics with 130/80(96) mmHg of the pressure and 370 ml/min of the mean flow rate. The simulated pressure waveform showed characteristic bimodal and large diastolic peak. For more sophisticated simulation, we are preparing the reproduction of interaction between coronary and systemic circulation and improving the controlling mechanism of coronary vascular resistance.

The leg varix are disorder of the valve of vein, and pulmonary thrombosis. The risk factor of the varix standing work, obesity, and familial history, women parous woman, and age. Approximately 2 times women have as much as men have. We prognosed venous characteristics by using ultrasound. We investigated 17 items of 40 people to examine the relations of the varix risk factor. We made the physical model and equation which is composed of 6 parameters. These 6 parameters were calculated by least-sqares method according to ultrasound image. We studied cluster analysis 17 risk factor items and these 6 parameters. The result of cluster analysis lead to the 4 major clusters. Age, a familial history, sex are same cluster and 5 indexes are also same cluster. Thus, the venous cross section change seems to be a relationship with varix in future.

Rotating a crank by legs is the popular way to transform manpower to rotative power, as used for bicycles. Thus ergometers or pedaling wheelchairs are used for the elderly or patients who have weakened muscles because it is useful for their training or rehabilitations. Then, how to design the crank or saddle lengths for these users? We confirmed it by musculoskeletal model simulations. The lower limb and crank were modeled as a four-bar linkage, fixing an ankle joint. Hip and knee joints were driven by the six muscles around thigh. We compared four types of subjects; the healthy people, quadriceps weakened, hamstrings weakened and all the muscles weakened. As a result, in all the cases, the high saddle was the best to extend the knee at bottom dead center. The optimal crank length was longer by weakened quadriceps and was shorter by weakened hamstrings.

Although pendulum-test is a simple and objective method to estimate spasticity by the use of the waveform of knee-joint pendulum motion, it isn't easy to unify lower-leg support situation at the beginning of its measurement without heavy burden on the subject. Large amount of fluctuation therefore exists in initial part of most waveform. We measured knee-joint angular velocity waveforms under the initial hip-joint positions of different angle as the first step to clarify its behavior. In each case, a damped oscillation was observed which constructed by 2~3 saw-tooth like spikes, and the higher the angle of the initial position was, the larger its amplitude became. Inverse simulation of the measured waveform showed that, the larger the initial angle of the hip-joint was, the larger the residual became. Present problem is to develop some way to be able to remove such an influence, reserving the present lower-leg support situation.

In knee-joint angular acceleration waveforms measured for pendulum-test of seated subject, some measurement errors may be caused by lower-leg supporting force remained after its start (residual force). Authors had corrected them temporally by approximating its damping pattern with a straight line. In this panel, we derived a better damping pattern from residual force measured on the way of the pendulum test. The residual forces in each of two normal subjects were measured 5 times under 3 initial knee-joint angles by a load sensor attached to palm for the lower-leg supporting. Normalization of measured damping patterns showed that it could be approximated by a quadratic function -a₁ t²-a₂ t+1, where a₁, a₂ were constants, the values of which might differ every measurement. Building such quadratic function in the inverse simulator for estimating spasticity, it is expected to be able to correct the influence of the residual force.

In pendulum-test of seated subjects, measured waveforms had frequently included much distortion due to the lower-leg supporting force remained after its release. The authors had tried to correct it by approximating the damping pattern of the force with a linear one. In this study, we used a more accurate damping pattern of quadratic curve in place of the linear pattern. The former pattern was derived from variation of lower-leg supporting pressure measured on the way of the pendulum-test. The results of inverse simulation to waveforms measured from two healthy subjects and two spastic patients showed that its accuracy was improved more highly than in the case of the linear pattern and there existed considerable difference between estimations of spasticity obtained under two patterns. A future work is to grope for possibility of practical use.

We have considered about control method of functional electrical stimulation (FES) based on equilibrium point hypothesis which said that human controls their equilibrium point and stiffness. Specifically, we proposed concepts of electrical agonist-antagonist muscles ratio (EAA ratio: an index of equilibrium point) and electrical agonist-antagonist muscles sum (EAA sum: an index of stiffness), in which agonist-antagonist muscles are controlled cooperatively. We have modeled a human joint movement and the model variables are controlled by EAA sum (joint stiffness). On the other hand, force length relation of human muscles is variable, because they have non-linear characteristic. Therefore, we have to clear how these models are dependent on posture when we use these. In this research, we cleared the relationship between joint angle and stiffness controlled by EAA sum.As the result, this relationship was not constant. Thus, we suggest that the model has to be corrected by posture.

In this experiment, two agar phantoms (70 mm 180 mm) with electrical conductivity of 6.61 m/s (muscle) and 0.99 m/s (fat) were used to construct a two-layered model (10 mm fat layer) assuming biological tissues. As the distance D between the current electrodes (40-100 mm, 4 conditions), the potential electrodes were placed at the inner 10 mm of the current electrode. Z was measured under six conditions in which the phantom thickness x was varied from 10 mm to 60 mm at 10 mm intervals. Z for x at the distance D between the electrodes was approximated as the sum of the exponential functions and constants. X, where the estimated value of Z is 105% of this constant value, was defined as the distance to reach the current, L. As a result of this experiment, L showed a linear correlation with D.

The deterioration of skin barrier function causes symptoms such as allergy as various chemical substances may enter human body. We think it is very useful to quantitatively evaluate the stratum corneum thickness and the water content of stratum corneum as the skin barrier function in domains such as dermatology, nursing science and the cosmetics development. We studied the new model regarded as the parallel model of the resistor and the capacitor applied the stratum corneum thickness of the skin stripped model measured the confocal laser scanning microscopy and the water content of stratum corneum of the skin stripped model measured the confocal raman microscopy. We found the stratum corneum thickness with the impedance has strong correlation with the stratum corneum thickness with the confocal laser scanning microscopy, and the water content of stratum corneum with the impedance has strong correlation with the stratum corneum thickness with the confocal raman microscopy.

Conventional models of human motor control can-not always possible to provide a clear understanding of the mechanism for controlling nonlinear dynamics of the musculoskeletal systems. In this study, we propose a model that combines the feedback linearization of the musculoskeletal system with an intermittent controller. This model can compatibly realize the nonlinear control of the musculoskeletal system and the simple motion planning in the workspace based on the minimum jerk criterion. Here, we show an example of a musculoskeletal model with a single joint.

Visualization of force is important in evaluation of manipulation procedures with precision motions and adjustments of slight forces. In recent years, force myography (FMG) measurement has been proposed as a method for measuring muscle activity. FMG focuses on the muscle bulge during motion. A typical FMG measurement could be conducted from contact pressure sensors attached to the body. In this study, a forearm-mounted FMG device consisting 16 pressure sensors was developed, and applied to pinch force estimations. As an experiment, the relationship between the contact pressure detected by each sensor and the pinch force measured by load cell was investigated during pinching motions. Pinch force estimation was realized by using the sensor signals correlating with the pinching motion. The visualization of forces exerted in medical procedures such as catheter feeding and vascular puncture can be realized by incorporating the FMG measurement into hand motion analysis.

The conditioning for athletes depends on their self-management or the experiences of their coaches. We focused on circadian rhythm which is related to physical and mental condition. The conventional method for estimating circadian rhythm is not suitable for daily measurement because of the measurement for more than 24 hours and restricting exercise in the daytime. Hence, we developed an algorithm for estimating circadian rhythm by using Electrocardiogram (ECG) during sleep. We evaluated the effectivity of this algorithm as compared with circadian rhythm measured by core temperature as the reference data. Both were related to strong positive correlation in data without first-night effect. Further the average of the error time (difference in the lowest time calculated by deep forehead temperature and ECG) was only 20 minutes. As the results, we succeeded in estimation of the time and heart rate value to reach the lowest point in circadian rhythm in normal sleep.

In this study, we report the features strongly related between electrocardiogram (ECG) and blood pressure pulse wave measured by the fabricated wearable device. The device consists of MEMS 3-axis force sensors, an electrocardiograph, a signal processing board and a fixed band. This device can measure blood pressure by the force sensors which are placed on the surface of the skin over a blood vessel. In the experiment, blood pressure was varied by breath-holding while simultaneously measuring blood pressure pulse wave and ECG. Then, features extracted from blood pressure pulse wave, its differential waveform, acceleration pulse wave and ECG were compared. The correlation coefficient between pulse pressure of blood pressure pulse wave and P wave amplitude associated with hypertension was 0.976. Also, the correlation coefficient between Augmentation Index of blood pressure pulse wave and ST segment elevation of ECG which is used for diagnosis of myocardial infarction was 0.915.

It has been demonstrated that sleep plays an important role for preventing dementia and other types of other diseases. Therefore, the sleep evaluation is important to find sleep-related problems and to improve sleep quality. In this study, to achieve an accurate and easy evaluation of the sleep quality, we developed a sleep stages classification method based on heart rate variability (HRV). Here, we focus on respiratory sinus arrhythmia (RSA) and propose a novel method to accurately detect the cycle length of periodic breathing. Our method analyzes periodically averaged HRV patten and can estimate the breathing cycle with higher resolution than that of conventional Fourier-transform-based methods. We applied our method to HRV during sleep and calculate RSA-related periodicity and amplitude parameters. Using these features together with conventional HRV parameters, we trained random forest to classify REM and non-REM sleep stages. Our result demonstrated that RSA-related features can improve the classification accuracy.

The majority of marathon deaths are caused by sudden cardiac arrest (SCA), which occur in approximately 1 in 57,000 runners. Although prompt resuscitation, including early use of AED, improves survival, the deployment of enough trained medical staff and AEDs is difficult due to increased cost. Moreover, most victims of exercise-related SCA have no premonitory symptoms. Therefore, we tried to use a novel approach to prevent sudden cardiac deaths (SCD) using monitoring system. As a result, 19 out of 20 runners had reasonable measurement results and sufficient monitoring without complications related to this trial was possible. However, many investigations and improvements, such as improving cost-effectiveness, reducing noise, and automating the monitoring system, are needed for practical application of these devices for athletes. As a next step, we would establish a novel strategy to reduce SCDs in athletes using next generation devices, which includes an alarm system with early application of AED.

For the diagnosis of respiratory diseases, measurement of breathing movement such as respiration rate and respiratory waveform is important. Measurement of breathing movement is also important in the evaluation of autonomic nervous system functions such as stress evaluation. As a respiration measurement method, there are a thermistor method, an inductance method, and etc. However, these methods have disadvantages such as weakness in mounting of sensors. In the previous study, we have investigated the change pattern of the chest wall was different between chest breathing and abdominal breathing using gyroscope sensors. In this study, we examined the measurement of respiratory movements during wear clothing using a 6-axis sensor (3-axis acceleration, 3-axis gyroscope). As a results, it was suggested that the respiratory waveform could be measured even if the 6-axis sensor was worn on the clothes. In addition, a signal similar to BCG was superimposed on the obtained respiratory waveform.

Respiration measurement provides us with the assessment of the autonomic nervous system (ANS) because of the interaction between respiratory system and ANS. Therefore, the purpose of this research was to develop wearable device measuring impedance to monitor respiration. Ten healthy subjects wore smart-wear and attached oronasal airflow. The oronasal airflow connected the conventional biopotential measurement device. In the experiment, each subject measured impedance for 1 minute during sitting. Also, they performed 2 respiration conditions (respiration rate (RR): 15 times/min and 30 times/min) to confirm whether the developed device can measure the variation of the respiration pattern. The RR was calculated by peak detection, and we compared that the signals measured by both devices. In both conditions, 8 out of 10 had the same RR on both devices. These results showed that the developed smart-wear can measure RR and respiration patterns.

Medical biometric information is required to be measured in a resting state or under constrained constraints. However, adverse effects on the measurement results caused by the environment at the time of measurement are implicitly accepted. A smart device that integrates these sensors with little wearing feeling into one device and can obtain biological information (pulse, electrocardiogram, body temperature distribution, body movement) that could not be measured at the same time from one clothes. Smart Textile can not only obtain measurement results without disturbance that releases the limitations of existing wearable devices, but also acquire biological information in all situations such as sleep, eating, exercise, etc.The ultimate goal is to acquire the big data of the whole living time by using the smart textile created by this research, and to develop new medical equipment and health care devices based on this information.

In Japan, pneumonia is the third leading cause of death, most of which is concentrated in the elderly, and pneumonia is the leading cause of death in the elderly. It is said that more than half of pneumonia is caused by aspiration pneumonia caused by aspiration. Aspiration is not only a cause of pneumonia but also a cause of death due to suffocation, and is increasing.In this study, we propose a non-invasive screening diagnostic system using multidimensional signals obtained from the neck. We report on the developed multi-dimensional biological signal acquisition device and signal processing method.

In order to prevent the need for nursing care in elderly, it is necessary to early detect the decrease of activity. In this study, we propose a new evaluation method for the risk for reduced activity by analyzing posture change from sitting-up to walking. Five sensor units which have three axes accelerometer and gyro-sensor, are attached to the subject's head, trunk, sacrum, thigh, and calf, respectively, to obtain sagittal, frontal, and twist angle changes through the appropriate digital filter. From the results of simulated data by a physical therapist, the characteristics of angle changes in each body part to complete the posture changes, could be observed at the same phase in active subject's data, whereas their characteristics could be observed sequentially in activity-decreased elderly. It is demonstrated that the present method can be useful for the early diagnosis of risk requiring the nursing care.

Evaluation of motor function is important in rehabilitation. In our previous studies, a method for estimating the timing of gait events (Heel-off, Toe-off, Initial-contact, Foot-flat) using an inertial measurement unit attached to the foot was developed. This algorithm detects gait events based on the zero-cross point or threshold of the angular velocity of the foot. However, the threshold value might need to be adjusted for each subject, which was not practical. In this study, the method using semantic segmentation model by convolutional neural network was proposed in order to develop an automatic detection method for gait events. In the walking of healthy subjects, the model was trained using the gait events measured using pressure sensors attached to a shoe as teacher data. It was shown that the gait events could be detected with generally good accuracy. In the future, it is necessary to verify the method with the hemiplegic walking.

Hemiplegia reduce the ability to walk independently and may lead to falls. Thus, fall risk assessment is important for precautionary measure. As the evaluation index of fall risk, asymmetry ratio of step time (ASY_step), standard deviation of step time (SD_step), and coefficient of variation of the root mean square waist acceleration (RMS_CV) are reported. However, since the standard deviation of each index is large, it is difficult to evaluate the risk with a single index. In this study, gaits for 10 hemiplegic and healthy subjects were measured using inertial sensors and relationships between ASY_step, SD_step, and RMS_CV were examined. As a result, there was no difference in RMS_CV between hemiplegic and healthy subjects. Although some subjects had ASY_step within the range of fallers, they had SD_step within the range of non-fallers. Since there are various causes of falls reflected in each index, it is necessary to evaluate using multiple indices.

Firefighters are highly exposed to hyperthermia condition because firefighter suit with high heat insulation property cannot dissipate heat generated from body by firefighting activities. One of the methods to predict heat stress is to monitor esophageal temperature increase directly, however, it's almost impossible to adapt such invasive method to firefighting activities. Thereupon, we developed heat transfer mathematical model to estimate core temperature increase using non-invasive sensor in order to monitor heat stress. Sensor unit is designed to estimate heat generation by accelerometer and heat dissipation by thermometer inside firefighter suit using heat conduction model. 16 firefighters wearing firefighter protective equipment and sensor units placed inside firefighter suit walked on the treadmill in 25 degree and 40 %RH environments, and walking speed was increased by 1.5 km/h every 9 minutes after 10-minute resting state. As a result, estimated core temperature was highly correlated with measured esophageal temperature at 0.97 correlation factor.