著者

Kiyoyuki Chinzei Akinobu Shimizu Kensaku Mori Kanako Harada Hideaki Takeda Makoto Hashizume Mayumi Ishizuka Nobumasa Kato Ryuzo Kawamori Shunei Kyo Kyosuke Nagata Takashi Yamane Ichiro Sakuma Kazuhiko Ohe Mamoru Mitsuishi

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.7, pp.118-123, 2018 (Released:2018-05-24)

参考文献数

3

被引用文献数

30

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AI-based medical and healthcare devices and systems have unique characteristics including 1) plasticity causing changes in system performance through learning, and need of creating new concepts about the timing of learning and assignment of responsibilities for risk management; 2) unpredictability of system behavior in response to unknown inputs due to the black box characteristics precluding deductive output prediction; and 3) need of assuring the characteristics of datasets to be used for learning and evaluation. The Subcommittee on Artificial Intelligence and its Applications in Medical Field of the Science Board, the Pharmaceuticals and Medical Devices Agency (PMDA), Tokyo, Japan, examined “new elements specific to AI” not included in conventional technologies, thereby clarifying the characteristics and risks of AI-based technologies. This paper summarizes the characteristics and clinical positioning of AI medical systems and their applications from the viewpoint of regulatory science, and presents the issues related to the characteristics and reliability of data sets in machine learning.

著者

降矢 典雄 大田黒 紘之 酒本 勝之

出版者

Japanese Society for Medical and Biological Engineering

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.52, pp.O-317-O-318, 2014

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This study is aimed at investigating possibility of Impedance CT applying two-dimensional analysis. Two-dimensional Electrical Impedance CT has two advantages. This analysis method can estimate internal conductivity distribution faster and the number of required electrodes is fewer compared to three-dimensional analysis. It is suitable for using clinical application. At first, we tried to apply easy filter using the ratio of the potential distribution. However the result of the analysis had the image with noise and indicated not so correct conductivity distribution. The results depend on the relationship between conductivities and positions of the object of different conductivity and tissue around it. It was found that the problem caused by the difference of dimensions occurred. Therefore we need to apply new filter to eliminate the influence of the difference of dimensions. By using a new filter based on Neural Network, it was suggested that the correct conductivity distribution can be obtained.

著者

日本学術会議医用生体工学研究連絡委員会医療技術開発学研究連絡委員会

出版者

Japanese Society for Medical and Biological Engineering

雑誌

BME : bio medical engineering (ISSN:09137556)

巻号頁・発行日

vol.11, no.7, pp.71-83, 1997-07-10

参考文献数

2

被引用文献数

2

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今世紀における科学技術の発展は目覚ましく, 医学・医療の分野においても, X線CT(Computerized Tomography)やMRI(Magnetic Resonance Imaging, NMR CT)など各種医療機器の開発によって客観的計測・診断技術や制御・治療技術あるいは情報処理技術が提供され著しく高度化された. 医師にとっては「見えなかったものを見る」, 「聞こえなかったものを聞く」, 「手の届かなかったところに手を伸ばす」という夢が現実のものとなり, 診断や治療技術はかつてないほど急激に進歩しつつある. 医用生体工学はこうした医学と工学の接点に位置する学問で, 工学の医学への応用にとどまらず, "科学技術と, 人間を含む生物との共生"という考え方を広め, かつそれを可能にする技術の開発を目指している. 医用生体工学は比較的若い学問分野であるがこの数十年間, 大学や研究機関のエム・イー関連学科や講座の研究者あるいは日本エム・イー学会およびその関連諸学会に支えられて発展してきた. また日本学術会議の医用生体工学研究連絡委員会および医療技術開発学研究連絡委員会の活動などによって, 医用生体工学に対する学問的および社会的な評価が徐々に高まってきた. 医用生体工学の研究環境は欧米に比べて著しく遅れていたが, 最近になって大学院に医用生体工学専攻, 学部に医用生体工学専門学科が開設されるようになった. 最近の世界的な動向をみても, 工学系の各分野がこぞって研究領域を医用生体工学分野べ拡充しようとしている.<br>しかしながら, 科学技術の想像を越える急激な展開は人間と機械の共生について新たな問題を投げかけている. さらにより現実的な問題として, この分野でも, 先端的な研究へのニーズや, 研究者および指導者はもとよりコメディカル職員などの人材養成に対するニーズが高まり, それらに対する早急な対応が迫られるようになった. しかも十数年後には人類が経験したことのない速さで社会の超高齢化が始まる. わが国のように労働賃金の高い先進国において, 高齢者の看護のために, 医用生体工学機器の適切な援用は極めて有効であり欠くことができない. さらに医療技術の向上を図るばかりでなく, 人々の精神的に豊かな生活を支援するための活動をすべきである. また今日のわが国の国際的な役割を考えるとき, 医用生体工学分野の果たすべき役割は国内的なものにとどまらない. 諸外国の医用生体工学関連機関との交流をさらに深めるべきである. 現在, 国際社会は複雑化してきており, 広い意味での国の外交は高度な専門知識なしには成り立たない. 医療分野で世界に貢献するには, わが国が率先してWHOやユネスコなどの国連の機関を通じて活動を広める必要がある. このような平和的活動こそ我が国が国際社会から求められているものであり, そのために進んで貢献すべきものと考える.<br>近年生命科学分野における研究の重要性が叫ばれ, その推進計画は先進各国で活発に討議されて答はひとつである. 50年前, 産官学の密接な連係と強力な指導力の下で実行された「傾斜生産方式」であった. 今こそ再び産官学の密接かつ強力な指導性が求められている.

著者

上村 雅之

出版者

Japanese Society for Medical and Biological Engineering

雑誌

BME (ISSN:09137556)

巻号頁・発行日

vol.2, no.1, pp.60-62, 1988

出版者

Japanese Society for Medical and Biological Engineering

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.46, no.1, pp.317-318, 2008

著者

Go Ito Shingo Otsuki Ai Shimada Hideomi Nakata Hidehiro Nakahara Toru Sawai Tadayoshi Miyamoto

出版者

Japanese Society for Medical and Biological Engineering

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.Annual60, no.Proc, pp.318-321, 2022 (Released:2023-05-12)

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Abstract: In our previous study, low-frequency, short-duration high-intensity interval training (HIIT) was performed for 8-12 weeks in untrained healthy subjects (Once a week, 3 sets, less than 10 minutes total training time), and the results showed that regardless of training intensity, maximal oxygen uptake (VO2max) and exhaustion time during maximal exercise increased by 6-13% and 33-89%. However, it is not clear whether similar results can be obtained in athletes who perform strenuous exercise on a daily basis. The purpose of this study was to investigate the effects of HIIT at different intensities on cardiorespiratory function and exercise performance during maximal exercise in college athletes. The subjects were 13 male college student athletes. The training was determined for each individual using a ramp exercise test to determine the maximum load, divided into 80% (TG80%) or 90% (TG90%) intensity training groups. and conducted once a week for 8 weeks. The training consisted of three bouts of exercises to volitional fatigue at TG80% and TG90% maximum work rate. Regardless different of training intensity, increased VO2max (TG80%: +11%, TG90%: +12%) and maximal work rate during the ramp exercise test (TG80%: +13%, TG90%: +16%) in both groups were observed after HIIT (P <0.01). Maximal exhaustion time during the HIIT (TG80%: +110%, TG90%: +95%) was also significantly prolonged in both groups after training (P < 0.05). In conclusion, low-frequency for short-duration once a week HIIT improves cardiorespiratory function and exercise performance during maximal exercise for athletes, regardless of its training intensity. These findings will contribute to the development of new and optimal exercise programs for various age groups and people, even competitive athletes.

著者

Osamu Uehara Toshimasa Kusuhara Takao Nakamura

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.12, pp.1-8, 2023 (Released:2023-02-03)

参考文献数

19

被引用文献数

2

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Deterioration of skin barrier function causes symptoms such as allergies because it allows various chemical substances to enter the human body. Quantitative evaluation of the thickness and water content of the stratum corneum is useful as a measure of skin barrier function in fields such as dermatology, nursing science, and cosmetics development. The stratum corneum is responsible for most of the skin barrier function, and this function has conventionally been evaluated using transepidermal water loss (TEWL). In this paper, we propose a new model for estimation of TEWL from measurements of the thickness of the stratum corneum and water content of the surface of the stratum corneum, and discuss the results of the measurements. By measuring the thickness and water content of the stratum corneum using confocal laser microscopy and confocal Raman spectroscopy, respectively, and examining the relationship of these variables with TEWL, we established a new potential model for estimating TEWL from these two variables. The correlation coefficient of the validation data was 0.886 and the root mean squared error was 8.18 points. These findings indicate the feasibility of qualitative evaluation of TEWL by measuring the thickness and water content of the stratum corneum.

著者

Tianyi WANG Shima OKADA Masayuki ENDO Masaaki MAKIKAWA Yuko OHNO

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.10, pp.11-17, 2021 (Released:2021-01-26)

参考文献数

34

被引用文献数

3 4

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Hiesho is the condition of having a cold sensation in one's hands or feet. This is a well-known health problem for young Asian females. However, the definition of Hiesho is still controversial. In this study, we aimed to develop a quantitative and non-invasive approach to determine Hiesho. Sixty-three young females participated in this research. Temperature difference (ΔT) between the forehead and foot sole was utilized to define Hiesho or non-Hiesho condition, and the result was crosschecked with that of a self-reported questionnaire. Central systolic blood pressure and augmentation index were measured to evaluate subjects' physiological indicators. The results of the questionnaire showed that 49% of young females (31 of 63 people) reported Hiesho. There was a significant difference in ΔT between non-Hiesho and Hiesho (1.85℃ and 5.55℃, respectively, p < 0.01). After cross-checking with the self-reported questionnaire, ΔT of 3.64℃ demonstrated acceptable reliability and accuracy for defining Hiesho. Central systolic blood pressure and augmentation index were not different between Hiesho and non-Hiesho. In conclusion, young females with Hiesho had drastically different temperatures at the forehead and foot sole. The temperature difference between the forehead and foot could be used as a quantitative and objective parameter for defining Hiesho.

著者

土井 正裕 並木 幸久 設楽 佳世 甲斐 昌一

出版者

Japanese Society for Medical and Biological Engineering

雑誌

生体医工学 : 日本エム・イー学会誌 = Transactions of the Japanese Society for Medical and Biological Engineering : BME (ISSN:1347443X)

巻号頁・発行日

vol.47, no.6, pp.477-483, 2009-12-10

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In order to validate Total Body Score (TBS) as an index for comprehensive evaluation of human body, we examined relationships between TBS and parameters which are correlated with metabolic syndrome (MS). Receiver operating characteristic (ROC) curve analysis showed that TBS is a useful index for MS screening. TBS had statistically significant correlations with systolic blood pressure, diastolic blood pressure, neutral fat, HDL cholesterol, visceral fat, and subcutaneous fat. The subjects who had low TBS showed statistically high probability to have one or more MS risk factors. The result suggested that assessment with cross-sectional biomedical data is useful for screening of MS risks.

著者

Toshiyo Tamura Ming Huang Tatsuo Togawa

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.7, pp.88-99, 2018 (Released:2018-04-12)

参考文献数

44

被引用文献数

12 49

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Wearable thermometers are popular devices for measuring body temperature during fever, as well as for monitoring basal temperature in women. They are easy to handle, inexpensive, accurate and provide continuous recordings. Most wearable thermometers are connected to a smart phone or tablet to display data. Many types of wearable thermometer are available, such as touch, patch and invisible (radiometric) types. In this review, we describe and discuss currently available wearable thermometers.

著者

Richard AJ Wain Nicolas J Gaskell Andrew M Fsadni Jonathan Francis Justin PM Whitty

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.8, pp.63-77, 2019 (Released:2019-02-15)

参考文献数

80

被引用文献数

1

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Simulation using computational methods is well-established for investigating mechanical and haemodynamic properties of blood vessels, however few groups have applied this technology to microvascular anastomoses. This study, for the first time, employs analytic and numeric models of sutured and coupled microarterial anastomoses to evaluate the elastic and failure properties of these techniques in realistic geometries using measured arterial waveforms. Computational geometries were created of pristine microvessels and microarterial anastomoses, performed using sutures and a coupling device. Vessel wall displacement, stress, and strain distributions were predicted for each anastomotic technique using finite element analysis (FEA) software in both static and transient simulations. This study focussed on mechanical properties of the anastomosis immediately after surgery, as failure is most likely in the early post-operative period. Comparisons were also drawn between stress distributions seen in analogous non-compliant simulations. The maximum principal strain in a sutured anastomosis was found to be 84% greater than in a pristine vessel, whereas a mechanically coupled anastomosis reduced arterial strain predictions by approximately 55%. Stress distributions in the sutured anastomoses simulated here differed to those in reported literature. This result is attributed to the use of bonded connections in existing studies, to represent healed surgical sites. This has been confirmed by our study using FEA, and we believe this boundary condition significantly alters the stress distribution, and is less representative of the clinical picture following surgery. We have demonstrated that the inertial effects due to motion of the vessel during pulsatile flow are minimal, since the differences between the transient and static strain calculations range from around 0.6–7% dependent on the geometry. This implies that static structural analyses are likely sufficient to predict anastomotic strains in these simulations. Furthermore, approximations of the shear strain rate (SSR) were calculated and compared to analogous rigid-walled simulations, revealing that wall compliance had little influence on their overall magnitude. It is important to highlight, however, that SSR variations here are taken in isolation, and that changing pressure gradients are likely to produce much greater variation in vessel wall strain values than the influence of fluid flow alone. Hence, a formal fluid-structure interaction (FSI) study would be necessary to ascertain the true relationship.

著者

Ryutaro Kasedo Atsuhiko Iijima Kiyoshi Nakahara Yusuke Adachi Isao Hasegawa

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.10, pp.26-31, 2021 (Released:2021-02-11)

参考文献数

15

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The rhythm of vocalizing a written language depends on a merge process that combines meaningless linguistic units into a meaningful lexical unit, word, or Bunsetsu in Japanese. However, in most previous studies, written language was presented to the participants in lexical units (word-by-word) with explicit inter-word (or inter-Bunsetsu) marks or spacing. Therefore, it has been difficult to conduct psychophysical assessment of the participants' own speed in segmenting meaningful units from unstructured written language when reading. Here, we hypothesized that the spontaneous reading speed of Japanese readers reflects their own punctuation process, even when sentences are written without punctuation marks or spaces. To test this hypothesis, we developed a new “self-paced sequential letterstring reading task,” which visually presents sentences letter-by-letter. The task required participants to push a button to proceed to the next letter at their own pace, hence allowing evaluation of the reaction time (RT) to individual letters. We found that the average RT decreased parametrically as the position of the letter approached the end of a Bunsetsu. Moreover, the RT increased drastically at the last letter completing the Bunsetsu. Participants were not shown any punctuation marks and not instructed to explicitly recognize the punctuations during reading. Therefore, these effects strongly suggest that the implicit and spontaneous punctuation is the origin of the rhythm in reading. These results show that spontaneous punctuation of letterstring affects the reading speed. The task we have developed is a promising tool for revealing the temporal dynamics of natural reading, which opens a way to shape the fluency of script-to-speech human interfaces.

著者

Kazuhiko Yamashita Tomoko Yamashita Mitsuru Sato Masahiro Inoue Yoshimasa Takase

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.9, pp.117-124, 2020 (Released:2020-07-30)

参考文献数

27

被引用文献数

3

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Chronic diseases such as diabetes, hypertension, and hyperlipidemia increase the medical costs for middle-aged and elderly people, thus requiring preventive intervention. Monitoring, maintaining, or increasing the number of steps walked per day could be expected to effectively reduce medical costs. We evaluated the medical costs for chronic diseases after the implementation of a step count monitoring system with an information communication technology that we hypothesized would efficiently decrease medical costs. We enrolled 342 subjects in the intervention group. An additional 1,025 subjects were selected as controls by matching with the intervention group for age, gender, and total medical costs accumulated in the year prior to the study. The subjects in the intervention group were provided with pedometers that were used with reading devices stationed throughout the city. The duration of the intervention was 18 months. The subjects were given health points based on their activity performance improvements such as the number of steps they walked. The medical costs for the 18 months before and afer the intervention were compared. The effect of cost reduction was evaluated by comparing the percent increase in medical cost from before to after intervention between the control group and the intervention group. After the intervention period, the medical costs increased in the control group but not in the intervention group. The step counts for the first three months and the last three months of the intervention period were assessed, and the results showed that an average step count of 8000 steps was maintained throughout the intervention period. Assuming that the control group showed a natural increase in medical costs, the results suggest that the natural increase in medical costs was suppressed in the intervention group during the intervention period as a result of using the pedometer technology and health points. Therefore, we found that encouraging the participants to proactively participate in walking was an effective strategy.

著者

Lulin Dai Jun-ya Okamura Gang Wang

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.9, pp.93-99, 2020 (Released:2020-05-15)

参考文献数

15

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Neuroscientists usually investigate stimulus selectivity by using a stimulus set and identifying the stimulus that evokes the largest electrophysiological responses averaged over a certain time period. However, the visual environment, and hence the brain activity, changes all the time. A method with sufficiently high temporal resolution for the investigation of dynamic changes in stimulus selectivity is desired. Here, we propose a method by dividing the usual time window for spike rate calculation into multiple smaller time windows. We applied this method to the analysis of temporal change in stimulus selectivity of inferotemporal (IT) cells in macaque monkey recorded previously using microelectrode while they were performing an object discrimination task, in which one object had to be discriminated from others regardless of change in viewing angle. The IT cortex is located at the last stage of the ventral cortical pathway, and is important for object recognition and discrimination. The proposed method theoretically possesses temporal resolution in millisecond order. We demonstrated its ability by following the changes in stimulus selectivity with temporal resolution as high as 20 ms. Furthermore, we divided the response time window into early phase and late phase. In each phase, single cell responses to images (4 objects × 4 views; 16 images in each of the stimulus set) were compared to identify the stimulus evoking the largest response. When comparing the early and late phases, 40% of the cells showed the largest response to the same stimulus (same object and same viewing angle); 13% of the cells showed the largest response to the same object but at different viewing angles; 20% of the cells showed the largest response to different objects at the same viewing angle; and 20% of the cells showed the largest response to different objects at different viewing angles. The dynamic change of stimulus selectivity from early phase to late phase may provide important information about the underlying neuronal mechanism for object recognition. Successful application of the proposed method to the analysis of IT cell activity demonstrates the validity and usefulness of the method.

著者

Yoshio Tsuchiya Takayuki Tanaka Tamotsu Kamishima

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.9, pp.181-188, 2020 (Released:2020-09-19)

参考文献数

21

被引用文献数

2

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Lumbar loading causes increased intervertebral pressure and is an important factor in low back pain. However, it is difficult to quantitatively judge the actions that affect lumbar load and the magnitude of lumbar load increase. Low back pain occurs not only in the workplace but also during activities of daily living. Therefore, it is necessary to investigate the factors inducing low back pain by measuring movements in various planes and determining the magnitude of the lumbar load. Accordingly, the lumbar spine should be examined during various movements. Several studies have examined vertebral bodies in the anteflexion posture. However, the relationship between body flexion angle and vertebral body angle during lateral flexion and rotation remains unknown. In this study, we proposed an estimation method for changes in vertebral body angle during lateral flexion and rotation in the lumbosacral region using a wearable sensor system we previously developed. The accuracy of the proposed estimation method was evaluated and demonstrated using X-ray images.

著者

Yusuke Yuasa Kenji Suzuki

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.8, pp.85-91, 2019 (Released:2019-02-23)

参考文献数

15

被引用文献数

1 10

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Asthma is a chronic respiratory disease, in which symptoms appear or intensify suddenly, even when patients are being monitored by doctors. Continuous measurement is important to monitor a patient's breathing without missing asthma attacks. In this study, we propose a method of continuous breathing monitoring in daily life using a wearable device. There are several studies using microphones to continuously monitor breathing during activities, which show various possibilities of extracting qualitative characteristics related to asthma. Other studies on breathing measurement using accelerometers or belts have achieved breathing detection and measurement without ambient acoustic noises. Taking advantage of the breathing sound and chest movement signals, they are simultaneously acquired using a chest-mounted device, which consists of a microphone, a photoreflector, and a flexible cover. Various acoustic noises and body movements are present in the environment. Thus, acquiring these two different signals in a complementary manner makes it easier to detect breathing in daily life. For monitoring asthma, we focused on detecting the breathing phases. Most of the asthma symptoms appear during the exhalation phase. Thus, phase detection plays an important role as an asthma symptom identifier. We developed a new algorithm for breathing phase measurement using both acquired signals. The algorithm is based on the periodicity of the chest movement signal. Breathing sounds are analyzed considering their frequency characteristics. In this paper, the basic performance of the proposed device in an experimental condition which is quiet and without participant movements is examined. The results of performance evaluation confirm that the left medial side of the second intercostal space is appropriate for placing the device and studying the correlation between breathing sound amplitude and tidal volume, which implies a potential to acquire tidal volumes. The phase measurement experiment shows that chest movement can be used for estimating the breathing period. The portable system developed can measure breathing in external conditions and tracking the wearer's location. Making the system portable expands the measurable situations and facilitates an acquisition of time and location information, which is useful in identifying the causes of asthma attacks.

著者

Yasuo Terasawa Hiroyuki Tashiro Yukari Nakano Takashi Tokuda Jun Ohta

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.5, pp.137-141, 2016 (Released:2017-01-12)

参考文献数

19

被引用文献数

2 5

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Implantable neural stimulators have recently attracted attention because of their potential applicability to the treatment of sensory neural disorders such as hereditary hearing loss and retinitis pigmentosa. However, the requirements for stimulation electrodes tend to be contradictory in some applications that require transmission of complex information to the nervous system, such as cochlear implants and retinal prostheses. They have to be sufficiently small to realize fine interfacing with the nervous system while remaining sufficiently large to inject enough charge to stimulate neurons without causing an irreversible electrochemical reaction. One solution to these requirements is to employ three-dimensional (3D) instead of planar electrodes. However, in conventional photolithography, the available material and size for fabricating electrodes are greatly limited. To overcome these limitations, we propose a novel fabrication process for stimulation electrodes, using mechanical micromachining. Using 3D bullet-shaped electrode increased the surface area by 3.6 times compared to conventional planar electrode with the same diameter. The proposed electrode, which was developed for retinal prostheses, showed sufficient charge injection capacity (CIC) to evoke light perception (phosphene) for blind patients. Furthermore, the CIC and electrode surface morphology remained stable during a six-month period of current pulsing in phosphate-buffered saline, which suggests suitability for chronic neural stimulation. The cause of the variance in the measured CIC and future applications of the proposed 3D electrodes were also considered.

著者

Hiroyuki Tashiro Yasuo Terasawa Mariko Kuwabara Koji Osawa Takashi Tokuda Jun Ohta Takashi Fujikado

出版者

Japanese Society for Medical and Biological Engineering

雑誌

Advanced Biomedical Engineering (ISSN:21875219)

巻号頁・発行日

vol.6, pp.8-14, 2017 (Released:2017-02-17)

参考文献数

17

被引用文献数

1 2

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We have developed retinal prosthetic devices based on suprachoroidal-transretinal stimulation (STS). The effectiveness and safety of such novel devices are confirmed by in vitro and in vivo tests based on scientific knowledge. Animal testing is especially important because it demonstrates the total safety of the device. We successfully developed a long-term evaluation system with automatic stimulation and measurement of electrochemical characteristics in freely moving rabbits. This system allows evaluation of long-term safety and change in electrochemical characteristics. In addition, we conducted a pilot evaluation of the safety of STS using bullet-shaped electrodes in rabbits. No obvious injuries were observed in all examinations. However, the array moved away from the retina in a few rabbits. Visual and electrical evoked potentials (EEPs) were recorded after three-month implantation. The function of the retinal neurons around the electrode is assumed to be maintained because EEPs were observed after three-month stimulation. However, the evoked potentials become indistinct with time in some rabbits. The development of implantable recording electrode capable of long-term evaluation is necessary for assessing the function of retina exposed to electrical stimulation. Long-term safety and change in electrochemical characteristics can be confirmed easily using this system. No histological difference was observed between the active and inactive electrodes, suggesting that the amount of charge used in the study can be safely injected. The charge injection capacity (CIC) of these electrodes provides an indication of the safety threshold for STS. The electrode array should have a curvature to fit the eyeball to avoid movement of the array away from the retina. The electrode height is slightly greater compared to the sclera thickness. Accordingly, methods to enhance the CIC vs. geometrical surface area are required if the electrode height is reduced. We were able to obtain an indication of the required performance for the stimulation electrode based on the safe charge injection for STS (CIC of approximately 90 μC/cm2 in PBS) and establish a system capable of evaluating safety and durability of retinal prostheses for long-term stimulation.

著者

斎藤 正男

出版者

Japanese Society for Medical and Biological Engineering

雑誌

BME : bio medical engineering (ISSN:09137556)

巻号頁・発行日

vol.17, no.1, pp.2-4, 2003-01-10

著者

池内 真志 生田 幸士

出版者

Japanese Society for Medical and Biological Engineering

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.43, no.4, pp.646-652, 2005

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The authors of this letter propose a novel "multi-layer hybrid scaffold" consisting of artificial blood capillary networks and cell-containing hydrogel for tissue engineering. The artificial blood capillary network was fabricated using a Membrane Micro Embossing (MeME) process, a unique, newly developed microfabrication process capable of fabricating freestanding thin polymer membrane micro-channels with both simplicity and high precision. With this process, a thin thermoplastic polymer membrane was placed on a deformable support substrate and embossed to fit 3D structures on a master mold by backpressure from the support. A one step heat-sealing method was used to successfully fabricate a highly branched "membrane micro-channel network" of biodegradable poly-lacticacid (PLA) micro-channels measuring 50 μm in width, 50 μm in depth, and 5 μm in wall thickness. The biocompatibility of the fabricated micro-channel was confirmed by culturing human umbilical vascular endothelial cells (HUVEC) on the micro-channel. This technology will provide a useful method for regenerating large organs in the future.