We have been developed a new transcutaneous communication system using human body as conductive medium. The transcutaneous communication system consists of an ASK modulator and its demodulator, electrodes, and carrier frequencies of 4MHz and 10 MHz are employed for full-duplex communication. Titanium mesh electrodes are used as a tissue induced electrode to acquire stable fixation between the electrode and tissue. The titanium mesh electrode has excellent characteristics as a scaffold, superior electrical performance. Animal experiments show that the transcutaneous communication system can communicate between everywhere on the surface of the body and everywhere inside the bodyb, and it is promising to be a next generation transcutaneous communication system.

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The annual statement from “Japanese society of Dialysis therapy” reports the number of patients on blood purification therapy, hemodialysis and peritoneal dialysis, was 309,946 and that of these induction was 38,165 in 2012. Renal replacement therapy (RRT) is composed of hemodialysis (HD), peritoneal dialysis and renal transplantation (RT). Patient under CKD stage 5, below eGFR 15ml/min/1.74m2, needs to prepare blood access in case of induction of blood purification therapy. It is well known the best modality of RRT is RT among the others, but the number of RT in Japan is very low compared in Europe and the United States.
There is no clinical evidence, but most widely HD therapy is 4.5 hour thrice-weekly in Japan. Recently it has been reported that frequent and long HD therapy improved the life prognosis of renal-failure patients as well as the deceased-donor RT. The frequent and long HD therapy means short-term home HD, long-term home HD and overnight HD. Increment of HD amount according hemodialysis product (HDP) probably leads to make activity of daily life on HD patients better. Here I want introduce the new modality of home HD.

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Safety designing is one of the most important tasks for medical technology development. However, the risks tend to arise unexpectedly and the safety designing is sometimes done just to avoid responsibility. "ANSHIN" designing is now started in collaboration of Kyoto University and Kyoto City University of Arts, where "Ethnography" the methodology of human-centered designing is used for medical-engineering development. The "ANSHIN" designing is also one of realization of NBM (Narrative Based Medicine) to cover the unexpected risks. These concepts will be explained taking an example of vitamin E-blended polyethylene development.

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Disorders of musculoskeletal disease, is directly linked inconvenience in daily life or the decrease of quality of life. Regarding the safety and quality of health care, public awareness increases, and expansion of the variation in medical content with the advancement of medical care or the complexity is concerned, therefore clinical practice guidelines began to be created. These guidelines have been used as a clinical handbook based on the evidence in order to explore a better solution for orthopedic surgeon in Japan. Now, I am going to touch on items related to prosthetic joint in clinical practice guidelines of osteoarthritis of the hip (2008) in this panel discussion. These are challenges to the prosthetic joint of interest for the clinician, and these measures are important. In addition, the current topics on joint prostheses also be mentioned.

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In this study, we focused on effects of protein and lipid molecules involved in the physiological environment of synovial joints on tribological behavior of materials used in articular surfaces of joint prostheses. Friction and wear of ultra-high molecular weight polyethylene, still the most popular bearing material for current artificial joint, and hydrogel artificial cartilage are evaluated experimentally in the various test lubricants prepared to have different compositions and effects of protein and lipid concentrations of the used lubricant are examined.Results indicated that the friction and wear of UHMWPE increased with increasing the protein concentration of protein concentration of test lubricants. The lipid concentration also had certain effects on the wear amount, although the its effect on the friction was limited. On the other hand, friction and wear of hydrogel were reduced by increasing protein and lipid concentrations.

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Since artificial joints are expected to function for a long period of time, animal and clinical studies cannot evaluate their durability. Instead, in-vitro mechanical tests have been employed, but they cannot fully reproduce in-vivo mechanical and biochemical environment. Thus, ensuring their clinical relevance is important. One way is to analyze failed implants and to develop in-vitro tests that can reproduce the failure. Since delamination at the rim of ultra-high molecular weight polyethylene (UHMWPE) components was often found in retrieval study of hip prostheses, we developed a novel delamination test that can reproduce clinically relevant delamination. This method was applied to evaluate the effect of various manufacturing processes on the delamination resistance. We also found lipid absorption in retrieved UHMWPE. Reproduction of the lipid absorption using squalene resulted in three to six times increase in wear of UHWMPE. This technique may enable us to reproduce more clinically relevant biochemical environment.

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The establishment of a prosthetic stem evaluation method is urgently needed, but there are no guidelines for quantitative evaluation. We have investigated problems with the initial fixation of a prosthetic stem using mechanical indices. In this study, the initial fixation of Stem A was investigated by comparison with Stem B as a control. Stem B is a representative stem frequently used in clinical cases. Displacement of Stem A was smaller than that of Stem B. No stress concentration was noted in Stem A. Although it is difficult to experimentally simulate bio-mechanical conditions, complex mechanical conditions could be reproduced using finite element analysis. Finite element analysis markedly saves time and labor compared to fatigue testing, which may increase the efficiency of evaluation.

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Introduction: The objective of this study was to explore the wear resistance of phospholipid polymer poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted cross-linked polyethylene (CLPE) acetabular liners against ceramic femoral heads. Methods: Four test groups i.e., untreated and PMPC-grafted CLPE liners against both cobalt-chromium-molybdenum (CCM) and zirconia toughened alumina (ZTA) ceramic heads, were tested according to ISO 14242-1 using a hip joint wear simulator. Results: After 10 million cycles (MC) of wear testing, the wear rates for the untreated CLPE liners were 4.5 mg/MC and 1.9 mg/MC against CCM and ZTA, respectively. And the wear rates for the PMPC-grafted CLPE liners were 1.4 mg/MC and 0.4 mg/MC against CCM and ZTA, respectively. For both femoral heads the wear rate for PMPC-grafted CLPE was statistically lower than the untreated CLPE. Discussion: The PMPC-grafted CLPE liners against ceramic femoral heads demonstrated reduced wear, and therefore may possess characteristics for optimizing in vivo performance.

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Many researches, such as wear resistance enhancement and metal surface modification for bone-implant bonding, have been conducted in order to improve the performance and function of artificial joint. In 2010, Nakashima Medical Co., Ltd. has launched Vitamin-E (dl-α-tocopherol) blended UHMWPE <BLEND-E> as knee joint bearing material that is expected superior durability. And then, as a hip joint bearing material, crosslinked Blend-E <BLEND-E XL> was placed on market in 2013. These materials have different properties in consideration of each biomechanics. In this paper, we would like to report about our development of biomaterials, especially of the Vitamin-E blended UHMWPEs, BLEND-E and BLEND-E XL.

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Although OXINIUM has many favourable characteristics, the biggest advantages of OXINIUM are as follows:

Lowest revision rate, based on data from the National Joint Registry in Australia.
No fracture and the lowest wear rate, the lowest wear rate, similar to ceramic and greater mechanical property, similar as metal
No risk of surface peeling, not a coating but gradient material
Best when paired with cross-linked polyethylene, no change of surface roughness in vivo

OXINIUM has many other advantage such as no phase transition, suitable for MRI, lower sensitivity for metal allergy, lower frictional coefficient, and so on.

These advantages will be introduced in the presentation to follow.

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We have been developing a total artificial heart (TAH) named the helical flow TAH (HFTAH) using helical flow pumps (HFPs). The HFTAH was designed to have a small size with enough performance, good durability and good anatomical fitting. The left and right HFPs were designed separately so that they could be applied also for bi-ventricular or single ventricular assist device. The elemental technologies are hydrodynamic levitation impeller, MPC polymer anti-thrombogenic coating and absolute pressure sensor. The HFTAH was implanted in goats and 100 days survival was obtained. With animal experiments, the problem that hydrodynamic bearing touched to the shaft and was worn by the sucking effect was occurred. As for the absolute pressure sensor, estimation of atrial pressure from its pulsatile amplitude has been investigated. We are expecting that the HFTAH would be an excellent total artificial heart as a next generation device.

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We have aimed to apply a cascade pump, which has a high ability to generate a pulsatile flow, to a total artificial heart. In a cascade pump, the pressure increases along the flow passage, and therefore the eccentric force occurs, which moves the rotating impeller from the outlet to the inlet. To reduce the force, we have developed a new cascade pump in which one flow from the inlet separates into four. This special structure enables the pressure distributions within the pump to be symmetric with respect to the X, Y, and Z axes. The pump performance test with bovine blood demonstrated 10 L/min against 170 mmHg at 3,200 rpm. Furthermore, we developed a system for measuring the eccentric force on the impeller. The eccentric force was 0.2 N on condition that the pump provided 9.3 L/min against 100 mmHg at 2,500 rpm.

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A total artificial heart which has single maglev motor with double centrifugal pumps has been developed. The maglev motor is set between a left pump and a right pump. The impellers of the left and right pumps are connected with a connecting rod passed through at the center of the motor. The impellers are levitated magnetically and rotated with identical rotating speed. The flow balance between the left and right pumps is achieved by shifting the levitated impeller in the axial direction. Zero power control is adapted for preload sensitive control. The maximum diameter and height of the pump are 76 mm and 61 mm, respectively. The pump indicates sufficient pump performance with the maximum flow rate of 20 L/min in usage condition. The flow rate is changed more than by 10 % of the flow rate of the pumps with an impeller position changing of 0.4 mm.

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We have developed a miniature axial flow pump Valvo Pump 2 that is intend to install the base of the ascending aorta. The new axial flow pump consists of a stator, an impeller in which four neodymium magnets are incorporated, and the impeller is directly driven by the stator. Rotation of the impeller is suspended by a passive magnet bearing in an axial direction, and by a hydrodynamic bearing in a radial direction. The magnetic passive bearing tolerates an axial load of 3.5 N, and the CFD analysis shows that the magnetic passive bearing can sustain the impeller in an axial direction. The hydrodynamic bearing is currently under development to obtain enough radial bearing capacity.Further studies are required, the new axial flow pump Valvo Pump 2 could be promising to be a new VAD.

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We have been developing several variations of circulatory assist systems based on nano or micro engineering technologies. One of the special features on the design of these new styles of circulatory assist devices will be a passive controllability according to the native signal transmission and hemodynamic response. In this study, we presented the design features and the research diversity for the development of passive-active circulatory support systems, such as artificial myocardial assist devices, circulatory valves, epi-cardial or vascular support systems.

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With the current development of the medical engineering technique, various ventricular assist devices have been developed and clinically applied, and several numbers of patients have socially recovered. However, the compactness, the lightness, the high-power and the durability will be the key for future advanced medicine since the ventricular assist device with higher performance and more safety is still desired. Now, it is necessary to reorganize the medical engineering techniques about ventricular assist device. With the reorganization, the individual characteristics of the ventricular assist devices and cardiopulmonary bypass pumps will be revealed which has been developed in the past, the present, or the future, that promotes the development of the research and clinical field including many medical devices. In this overview, we focused the geometry of the blood pump, and compared about the pump performance, the hemo-compatibility, the performance for the clinical use to reorganize the medical actuation technique.

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A centrifugal pump utilizes the outer pressure of a swirl and do not need any airfoil. A centrifugal pump produces a constant swirl to obtain a constant pressure without regard to flow rate. Recent implantable VADs are mostly centrifugal pumps with non-contact bearings. There are two types for non-contact bearings: one is magnetic bearing and the other is hydrodynamic bearing. The magnetic bearing is composed of stator coils and position sensors to maintain the rotor at a position. The hydrodynamic bearing utilizes locally high pressures generated by fluid squeezed into a wedge-shape channel or a step channel composed of relatively moving surfaces. These allow patients to be discharged to home or to jobs.

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Axial flow blood pumps are widely used for mechanical circulatory support including implantable left ventricular assist device and peripheral intra-aortic ventricular assist device. The miniaturization of the devices plays more and more important role in extending the treatable therapeutic options using these blood pumps. On the other hand, miniaturization will be accompanied with higher motor speed and lower energy efficiency, and blood compatibility of the devices must be taken special care in their developmental stage.

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A pneumatic ventricular assist device (PVAD) and a pneumatic total artificial heart (PTAH) system were developed. The size and weight of the driver with 2 battery pack are 250 x 110 x 210 mm and 4.3 kg, respectively. The PVAD with Nipro VAD blood pump using the driver achieved the mean pump flow ranging from 3.4 to 6.7 L/min and the mean electric power consumption ranging from 8.0 to 19.7 W in the overflow type circulation mock test. The PVAD was also examiend for 28 days in the chronic animal test using calf. The bypass flow and the electric power consumption were maintained at 4.1+/-0.4 L/min and 13.3+/-0.4 W, respectively. The PTAH using the 2 drive unit was evaluated in the acute animal test using calf. The mean pump flow ranging from 3.9 to 5.4 L/min and the mean electric power consumption ranging from 5.3 to 17.6 W were achieved.

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Roller tube pump, a type of positive displacement pump, is used for the blood purification treatments as a blood pump. Their structure is very simple. A rotor with some rollers rotates along blood tube. Blood is sucked in tube by restoring force of squeezed tube and pushed out by extrusion force of roller. The advantage of the roller pump is that it is excellent in terms of operability, safety, economic effectiveness and reliability. That is why roller pump is suit for blood pump in blood purification in the proper use

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Cascade pump has a rotating disk with circumferential vanes. Flow channel is constructed around the circumferential space of the rotating disk. The cascade pump has thin structure because the inlet and outlet ports are set on the same plane with the rotating disk. The gap between disk surface and casing should be less than 0.05 mm to prevent pressure loss through the gap in the cascade pump. The gap of the cascade pump produces higher hemolysis and thrombus in it. The disk surface gap is minimized with modifying the impeller to ring shape with a radial self-bearing motor to achieve better blood compatibility. Developed pump has maximum diameter of 59 mm and a thickness of 22 mm. Maximum flow rate and head pressure are 7 L/min and 330 mmHg, respectively. The hemolysis property is just two times of the commercial based blood pump and sufficient for mechanical circulatory support.

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The design requirements of the blood pump for implantable ventricular devices and total artificial heart are heavily affected by the anatomical limitation such as the intrathoracic space capacity and blood vessel layout. It is also necessary to modify the design of blood pumps for built-in use in the case of integrated pump lung system. Limitation occurs at the blood inflow position to the oxygenator whether the configuration of oxygenator was cylindrical or box shape. The design and structure of outflow port in the blood pump was decided according to the smoothness of the blood flow.Our research group tried to design the blood pumps specialized for built-in apparatus. In this study, we report a newly designed the multi-stage centrifugal pump named Sequential Flow Pump that two steps of pressurization is possible with one impeller.

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The application of MEG has been quickly expanded into both basic and clinical research fields. However, we now face several limits of SQUID-based systems. Firstly, the helmet-shaped sensor placement is fixed despite different size and shapes of the subject's heads. Moreover, for the wall thickness of the liquid helium container, sensors are located far from the scalp surface. Secondly, speedup of the signal processing is necessary for the demand of high signal frequency, i.e. 200-2,000 Hz, for multi-channel recordings, i.e., 300-1,000. Thirdly, the source estimation algorithm cannot catch up with the development of multichannel MEG systems. In this report, we show the recent development of the MEG application while we discussing an ideal MEG system with non-SQUID sensors in the near future.

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Magnetocardiography (MCG) is a noninvasive method to record weak magnetic fields generated around the heart using a non-contact sensor with high sensitivity. Clinical applications of MCG include evaluation of myocardial depolarizing/repolarizing processes, myocardial ischemia and pathophysiological diagnosis of arrhythmias. It is notable that MCG has also been applied to prenatal diagnosis of fetal cardiac diseases as extremely weak signals from a fetal heart can be detected using a SQUID system on the maternal abdomen without contact electrodes. For diagnosis of myocardial ischemia, MCG shows some advantages over conventional diagnostic modalities. MCG is superior in detecting tangential & vortex currents of myocardium to electrocardiography, making it possible to diagnose coronary artery disease even at rest with high sensitivity and specificity. In this paper, current status and future direction of clinical applications of MCG and limitations of the technology will be discussed.

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To shield magnetic noises, magnetically shielded rooms (MSRs) are used for biomagnetic measurements, etc. To evaluate the shielding factor SF, the magnetic noise is applied by coils. However, SFs depend on the size and position of the coils, so standard of JEITA EM-4502 evaluating SF for extremely low frequency region of less than 1 Hz without eddy current effects, in which the shielding factor SFo for the uniform magnetic field can be estimated by using coils within 10 % error, has been already published. Then, a standardization for low frequency region, e.g. 50 Hz, taking account of eddy current effects, is being discussed at present. In this paper, to establish standard methods for evaluating SF for low frequency region using coils, the effects of the eddy currents on SFs are investigated using a linear eddy current analysis of an actual MSR made of copper and permalloy plates.

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Optically pumped atomic magnetometers (OPAMs) using alkali metal vapors contained in glass cells have reached sensitivities comparable to and even surpassing those of SQUIDs. In recent years, OPAMs operating under spin-exchange relaxation-free conditions have reached sensitivities the sub-femto tesla range. OPAMs have the intrinsic advantage of not requiring cryogenic cooling. Therefore, OPAMs are currently expected to overtake SQUIDs. After describing principles of the OPAM, we introduce recent results of biomagnetic field measurements such as MCG and MEG. Finally, we describe the feasibility of atomic magnetometers as magnetic sensors for measuring MEG and MRI signals simultaneously.

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Currently, SQUID is the most sensitive of the magnetic sensor and is used for the measurement of biological fields. However, dissemination of the device to the medical field realistically is very strict due to the big size of the device, in terms of introduction and maintenance costs. In particular, a dewar for holding a low temperature is required in order to immersion in liquid helium for operating the SQUID element. The distance of the dewar from the head surface, and also the dewar surface from the SQUID element, act as restraint for accurate measurement. This paper proposes a sensor for the biomagnetic field measurement with magnetic tunnel junction (MTJ) devices. It can be operated at room temperature and is brought it into close contact with the head. We describe the necessary technical challenges toward its realization and the feasibility in the future.

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Recent experimental studies have shown the influence of instantaneous phase and amplitude of ongoing oscillations in electroencephalogram (EEG) and magnetoencephalogram (MEG) on the performance of a variety of cognitive tasks. Hence, it is important to estimate precisely the instantaneous phase and amplitude of the ongoing oscillations. Moreover, the ongoing oscillations are synchronized and/or reset by external stimuli. These phenomena are caused by phase shifts of the ongoing oscillations. Therefore, it is important to investigate the dynamics of the phase shifts. First, we develop a novel method that can be used to estimate the instantaneous phases and amplitudes of the ongoing oscillations with high accuracy by modeling the phase and amplitude as Markov random field (MRF) models. Second, we developed a novel method for detecting phase shifts of the ongoing oscillations in a single trial based on the above mentioned method. By using our method, we detected phase shifts of the alpha rhythm in flash EEG data. Moreover, we showed that phase shift relates to variability in reaction times.

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Bluetooth and Bluetooth Low Energy are wireless transmission scheme related to the IEEE 802.15.1 standard, and it is not developed only for medical and healthcare applications, but recently it has been widely used as a tool for connecting vital sensing devices to a smartphone. On the other hand, the IEEE 802.15 working group has released standards such as 802.15.6, 802.15.4j and 802.15 specialized for medical and healthcare applications. In this speech, I present the detail on recent WPAN (wireless personal area network) standardization activity for medical and healthcare applications in the IEEE 802 working group.

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Recenly wireless medical and helthcare has been receiving attention. In many cases, Bluetooth has been applied to these wireless medical and healthcare devices as a wireless communication scheme. There has been an increase in the number of cases that more reliable links are demannded and that multiple number of sensors are required to be linked in a network synchornously. In these cases, it is considered to install a Body Area Network (BAN). In this paper, BAN application to our wireless vital sensor 'Silmee' and its further discussions including international standardizations are considered.

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A 400MHz ultra-low-power wireless transceiver for Body Area Network has been successfully developed. This transceiver supports IEEE 802.15.6 compliant mode with data rate up to 455kbps for typical medical data monitoring such as blood pressure, body temperature and ECG, and a proprietary 3.6Mbps high-speed mode for the monitoring of multi-channel EEG and ECoG. The power consumptions of receiver and transmitter are 2.2mW and 2.3mW, respectively, and are an order of magnitude smaller than current products. This power reduction extends battery run-time of medical sensor node, and contributes to enhance work efficiency of medical staff and reduce form factor of the sensor node devices.

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The introduction of wireless communication to clinical settings is rapidly progressing. The use of wireless communication technology has enabled the hospital staff to gather and transmit information and increase efficiency by connecting to high tech medical devices, e.g. communicating with implanted medical devices. The use of medical devices outside hospitals has increased: Not only implanted devices like cardiac pacemakers but home use machines such as respirators are increasing. In such an environment, it is imperative to prevent electromagnetic interference with medical devices and to ensure the compatibility of wireless communications. Furthermore, taking measures to protect against the electromagnetic noise the various devices used in a hospital emit is important. In this paper, we show the current status of the above issues and how to manage them.

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There are many electromagnetic sources in medical environment. Not only electromagnetic compatibility (EMC) problems but also safety of human exposure to electromagnetic fields (EMF) is an important issue. Especially occupational exposure to extensive high EMF of MRI operators has become large concern because of very high intensity of EMF around MRI systems. There were many discussions on MRI operators during introducing EU Directive on occupation EMF exposure. In this presentation, the rationale of the international guidelines for human exposure to EMF, which issued by International Commission on Non-Ionizing Radiation Protection (ICNIRP), are introduced and recent activities on research and legislation on EMF safety are summarized.

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Medical devices have greatly contributed to the therapy and diagnosis in Japanese healthcare system. The medical device industry is one of the industrial areas which can develop global economic growth, based on the basic technologies that it is proud of in the world. Most medical device manufacturers in Japan have excellent basic technologies, but it is very hard to utilize their unique capacities and experiences in research and development of new products. We, industry, academia and government in Japan have a great responsibility for promoting to satisfy the clinical needs in the world by producing high quality devices.

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To apply outcomes from researches into clinical practices, translational researches have been done from the early part of this century. Our division is doing the researches as well to develop methods for evaluating safety and efficacy of new medical devices and clarify factors necessary for the evaluation, some of which are shown in this presentation.For example, our division plays a role as secretariats of working groups for developing guidelines for evaluating efficacy and safety of emerging medical devices. Currently, nineteen guidelines have been open to public and some of these have been already utilized for reviews of the medical devices for approving their marketing by PMDA.Standardization of technologies and evaluation methods for new medical devices is another important factor for developing the medical devices for clinical practices. To notify its importance to stakeholders, we are trying to put out summarized information on current activities on medical device standardization.

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Medical devices have to provide efficacy and the benefit must outweigh the risk. In design development phase, we should adequately evaluate effectiveness and safety with assuring quality. Since effectiveness and safety of medical device are affected by user technique and combined medical device and drug, it is necessary to fully understand the characteristics of medical device under development. Risk management (risk analysis, assessment and control) are conducted based on defined characteristics. Items needs risk control must be evaluated for the machinery and appliances. Although there is no direct relativeness, insurance coverage and marketing strategy (usability, indication of differentiation from other products, etc.) after marketing approval should be considered during selection of evaluation items and methods.Additionally, we should consider and take measures for ensuring reliability, appropriateness and adequacy during above mentioned process.

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In 2011, the Ministry of Health, Labour and Welfare started a national project to establish systematic infrastructure in several hospitals and universities for innovating the pharmaceutical and medical device development. Our institute was selected as only one institute for the development of medical devices. We are now driving several projects for medical device development especially in the cardiovascular field with many academic researchers and engineers. In these processes, a number of problems became clear, that is, it is difficult for them to judge what and how they should do at each specific developmental stage. It seems to be hard to get general and standard strategies for the development of medical devices because they are unique to each devices, which is one of the major reasons that developers with fewer experiences could not achieve successful development of medical devices. Here, we show key points to achieve successful development for academic researchers.

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In this lecture, the progress, the accomplishment, and the foresight of national programs
initiated by MEXT and MHLW will be introduced. The outcomes from the Translational
Research (TR) program started in FY 2007 and the subsequent program started in FY 2012
is remarkable, for example 22 IND trials registration (including 9 devices and 7
regenerating medicines), and 5 manufacturing and distribution approval (including 4 devices)
by the regulatory agency, from the MEXT program. Thereby, research and development based on
the Pharmaceutical Affairs Law became the common practice and the R&D pipeline in academic
sector has been established. Should the new funding agency to be in operation in FY 2015,
apply well-designed instructions and proposal forms for budget application, and rigorous
review procedure based on the regulatory science principle, along with the precise project
management, our country would become the most prominent innovation-oriented nation
in the world.

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Instruction and consultation about quality and safety view, from the initial stage of the development in order to create innovative medical devices.
This consultation system is mainly for University, Laboratories and venture companies who has very progressive idea or studies but the little experience about the regulation.

Instruction and consultation about quality and safety view, from the initial stage of the development in order to create innovative medical devices.

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In healthy subjects, blood pressure levels are 10-20% lower at night than in the day. This condition is called dipper change. The 24-hour ambulatory blood pressure monitoring allows detection of abnormal circadian blood pressure patterns, such as morning blood pressure surge and non-dipper change in patients with normal clinic blood pressure. Morning blood pressure surge is associated with an increased risk for hypertensive target organ damage, and with higher cardiovascular morbidity and mortality. We previously reported that repeated episodes of end-apneic arousal or hypoxia and consequent sleep fragmentation were associated with an elevation in nocturnal blood pressure, possibly leading to sustained hypertension and LV hypertrophy. However, the relationship between sleep quality and blood pressure changes during sleep has not been well described. This presentation will review a novel methodology for monitoring of nighttime blood pressure.

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This paper describes a method for estimating blood pressure by using just one pulse wave sensor. Generally, to be able to measure blood pressure, cuffs are required for applying pressure, blood pressure measurement is time and effort consuming, and continuous measurements cannot be performed. If we are able to measure blood pressure without the use of cuff, we can solve these problems. However, features that obtained by pulse wave sensor are highly vulnerable to noise generated by various factors. In this paper, we evaluated the features using Taguchi's signal-to-noise ratio, and we extracted the features that are robust against noises. The effectiveness of the proposed method confirmed through the experiment of blood pressure estimation.

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We developed a new cuff-less blood pressure measuring instrument using our phase shift technology. Using the new device we can continuously and noninvasively get information on the blood pressure per pulsation of the blood vessel. However the traditional medical device used in hospital or in our house is not able to measure continuously the blood pressure. Over the past many years, there have been numerous studies on cuff less blood pressure monitor, but a new medical device capable of detecting invasively blood pressure have not been developed. This study describes development of a new type of cuff-less blood pressure instrument which is designed to operate with an optical sensor.

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In general, it is necessary to tighten with a pressure manometer such as a cuff for measuring blood pressure (BP). There are, however, discomfort and botheration by tightening with a cuff and wearing the manometer device. We have felt that the device lacks in portability and comfortability for users, and the existing instrument is inadequate for BP monitoring at any time or full-time. In this study, it is intended to carry out BP monitoring using a photoplethysmography (PPG) in consideration of usability. When he/she estimates the BP by using biological signals of the circulatory system, the pulse wave and electrocardiogram are often used. We have tried to estimate BP using only and just the volume pulse wave in order to achieve a more simple measurement although it is common to use such two kinds of biological signals. That is why we have developed an attachment device on a smartphone for measuring PPG at a finger. In addition, we have built a client-server system to be able to estimate BP at that time from the pulse wave data sent from the smartphone. This system will enable users to be released from the constraints of time and place to BP monitoring.

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We have developed cuffless blood pressure monitoring system to prevent sudden death while driving. This system monitors driver's blood pressure only by gripping a steering wheel. The system measures ECG of the driver through metal electrodes installed on both sides of the steering wheel, and measures pulse wave from an optical sensor built in the steering wheel. We use a 525 nanometer green light-emitting diode which reduces surface reflection from human body and enhances the signal-to-noise ratio of the pulse wave. We extracted cardiovascular-related features by analyzing the pulse wave as well as calculating pulse transit time from ECG and the pulse wave. Then we estimated blood pressure using these features as explanatory variables. We modeled blood pressure estimation by multiple linear regression analysis using 1008 subjects' data composed of blood pressure measured by automatic sphygmomanometer, ECG, and pulse wave in a laboratory. Then we verified the accuracy of the model using our steering wheel sensor system, which indicates that the system has a potential to estimate blood pressure precisely only with a few problems.

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Since the response of the brain to a sensory input is dependent on the state of the brain that fluctuates spontaneously with time, it is very important to know the spontaneous activity of the brain for the stimulus-to-response property evaluation. Recently, green auto-fluorescence (GAF) emitted from mitochondrial flavoprotein has been proved to be correlated with the neuronal activity of the brain. The GAF imaging technique has been used for brain mapping. However, it has not been used for the spontaneous activity of the brain because its signal-to-noise ratio (S/N) is low. To improve S/N, we have optimized the fluorescent measurement system and introduced digital signal processing techniques. In this presentation, we will show that GAF of the brain has a component which is correlated with spontaneous electroencephalographic activity, and discuss utilization for the functional imaging of spontaneous brain activity.

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We are investigating a firing prolongation of the rat striatal neuron after the repetitive optogenetic stimulation observed in an acute striatal slice. In this report, we tested whether the prolongation could be observed in vivo. Wistar Thy-1.2 promoter ChannelRhodopsin-2 Venus Rats were anesthetized and placed in a stereotaxic frame. A wire tetrode was coupled with a 500 μm plastic optic fiber and inserted into the striatum of the rat anesthetized by urethane. We were able to observe the firing prolongation after repetitive photostimulation using the tetrode with the optical fiber.

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Advances in microfabrication technology have enabled the development of multi-contact electrodes with precise inter-contact spacing from tens to hundreds of micrometers. Using this technology, we can record multiple neural activities in the brain simultaneously. Based on the local field potentials (LFPs) recorded from each contact, it is possible to estimate the current source density (CSD), which is considered to reflect synaptic input. Analysis of both spike activities, reflecting the output of neurons, and CSD is a promising approach to examining the functional properties of the neuronal circuits underlying animals' behavior. However, the standard CSD method does not always reconstruct the actual CSD. A few methods have been proposed to overcome this problem, but these have not been tested using the LFPs of behaving animals. We present the preliminary results of a comparison between standard and new CSD approaches to the LFPs recorded from the prefrontal cortex of a behaving monkey.

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A Si opto-neural probe having multiple waveguides and metal cover have been developed for the first time. This neural probe consists of 16 recording sites, 3 optical waveguides, and metal waveguide cover for light leakage suppression. Electrochemical properties of the recording sites were carefully evaluated, and it was indicated that the Si opto-neural probe had appropriate characteristics for neuronal recording. The optical stimulation to the neurons expressing ChR2 were also demonstrated using the Si opto-neural probe. As a result, multisite optical stimulations were successfully achieved without light leakage from the optical waveguide because of the metal cover. From in vivo experiments, optically modulated local field potentials (LFPs) were also perfectly recorded using the Si opto-neural probe with three optical waveguides. In addition, current source density (CSD) analysis was performed to the recorded LFPs, leading to that light induced membrane current sank in locally stimulated area. The Si opto-neural probe with multiple optical waveguides and metal-cover is one of the most versatile tools for optogenetics.

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As multilevel physiological models is growing in size and complexity, it became more important to establish a platform enhancing model sharing and reuse. Toward this end, PhysioDesigner, a versatile platform for multilevel physiological modelling, has been developing. The version 1.0RC1 has been released on March 2014. Main features of PhysioDesigner are the following: explicit expression of model's hierarchical structure based on modules. Hybrid multilevel modelling incorporating SBML models. Large scale modelling using template/instance framework, integration of morphological data, and so on. In this presentation, focusing on a newly developed function, i.e. time series integration and visualization in 3 dimensional space, we introduce PhysioDesigner. With the new function, it is possible to integrate experimentally obtained or simulated time series data in modules, which can be used to constrain partially model's dynamics, or to drive mathematical model. Visualization function makes it easy to check a simulation results of models including morphological data.

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