Non-invasive Sensor System Research Articles

Direct, real-time monitoring of superoxide generation in isolated mitochondria

Mitochondria are one of the major sources of reactive oxygen species (ROS) in mammalian cells. The generation of ROS underlies many physiological and pathophysiological processes that occur within cellular systems. Superoxide () is the proximal ROS generated during electron ‘leakage’ from the mitochondrial electron transport chain (mETC) and is known to be released at mitochondrial complex I and complex III. Monitoring mitochondrial production directly and in real-time offers the potential to improve understanding of the complex mechanisms involved during mitochondrial generation. This study reports the novel application of a cytochrome c functionalized amperometric sensor for monitoring generation in isolated mitochondrial fractions. The non-invasive sensor system described allowed a comparison of production following specific inhibition of complex I and complex III of the mETC to be made directly and in real-time.

216 マイクロ3次元振動アクチュエータを用いる卵細胞のローカルダメージ再生回復システム

In this study, a new non-invasive micro sensor system is developed to detect compliance of minute living cells and tissues by using dynamic response of piezoelectric vibrator. 3-D micro actuator is also developed to enforce dynamic stimulations. The sensor was controlled by micromanipulator system, while dimensions and morphologies of the cells were measured by inverted phase contract microscope system. The method has shown that the reaction of living cells might have frequency dependence against vibrating stimulations by the actuator. Also, experimental studies have shown that dynamic stimulations accelerate damage recovery of minute living cells.

Synchronization analysis of the uterine magnetic activity during contractions

BackgroundOur objective was to quantify and compare the extent of synchronization of the spatial-temporal myometrial activity over the human uterus before and during a contraction using transabdominal magnetomyographic (MMG) recordings. Synchronization can be an important indicator for the quantification of uterine contractions.MethodsThe spatialtermporal myometrial activity recordings were performed using a 151-channel noninvasive magnetic sensor system called SARA. This device covers the entire pregnant abdomen and records the magnetic field corresponding to the electrical activity generated in the uterine myometrium. The data was collected at 250 samples/sec and was resampled with 25 samples/sec and then filtered in the band of 0.1–0.2 Hz to study the primary magnetic activity of the uterus related to contractions. The synchronization between a channel pair was computed. It was inferred from a statistical tendency to maintain a nearly constant phase difference over a given period of time even though the analytic phase of each channel may change markedly during that time frame. The analytic phase was computed after taking Hilbert transform of the magnetic field data. The process was applied on the pairs of magnetic field traces (240 sec length) with a stepping window of 20 sec duration which is long enough to cover two cycle of the lowest frequency of interest (0.1 Hz). The analysis was repeated by stepping the window at 10 sec intervals. The spatial patterns of the synchronization indices covering the anterior transabdominal area were computed. For this, regional coil-pairs were used. For a given coil, the coil pairs were constructed with the surrounding six coils. The synchronization indices were computed for each coil pair, averaged over the 21 coil-pairs and then assigned as the synchronization index to that particular coil. This procedure was tested on six pregnant subjects at the gestational age between 29 and 40 weeks admitted to the hospital for contractions. The RMS magnetic field for each coil was also computed.ResultsThe results show that the spatial patterns of the synchronization indices change and follow the periodic pattern of the uterine contraction cycle. Spatial patterns of synchronization indices and the RMS magnetic fields show similarities in few window frames and also show large differences in few other windows. For six subjects, the average synchronization indices were: 0.346 ± 0.068 for the quiescent baseline period and 0.545 ± 0.022 at the peak of the contraction.DiscussionThese results show that synchronization indices and their spatial distributions depict uterine contractions and relaxations.

Piezo micro probe sensor system to detect environmental stresses induced in living cells and tissues

In this study, a new method of noninvasive sensor system is developed to detect mechanical stresses induced in minute living cells and tissues. The bending mode of vibration, excited impulsively by piezoelectric ceramics, is utilized in a small clamped-free beam type vibrator which is mounted on micromanipulator system. Experimental studies have been carried out by using living egg cell of killifish and also three dimensionally tissue-engineered regenerated cartilage. The method has shown enough capabilities as a micro-sensor to detect mechanical stresses which are environmentally induced in living cells. Also, it has suggested a possibility to provide useful information to decide whether three dimensionally cultured cartilage tissue has enough biomechanical properties for transplantation treatment of damaged cartilage.

245 微少生体細胞に対する動的理学刺激の付加および評価システムの開発

In this study, a new non-invasive micro sensor system is developed to detect compliance of minute living cells and tissues by using dynamic response of piezoelectric vibrator. 3-D micro actuator is also developed to initiate dynamic stimulations. The sensor was controlled by micromanipulator system, while dimensions and morphologies of the cells were measured by inverted phase contract microscope system. The method has shown that the reaction of living cells might have frequency dependence against vibrating stimulations by the actuator. Also, experimental studies have shown sensor's capability to detect mechanical properties of minute living cells.

Development of built-in type and noninvasive sensor systems for smart artificial heart.

It is very important to grasp the artificial heart condition and the physiologic conditions for the implantable artificial heart. In our laboratory, a smart artificial heart (SAH) has been proposed and developed. An SAH is an artificial heart with a noninvasive sensor; it is a sensorized and intelligent artificial heart for safe and effective treatment. In this study, the following sensor systems for SAH are described: noninvasive blood temperature sensor system, noninvasive blood pressure sensor system, and noninvasive small blood flow sensor system. These noninvasive sensor systems are integrated and included around the artificial heart to evaluate these sensor systems for SAH by the mockup experiments and the animal experiments. The blood temperature could be measured stably by the temperature sensor system. Aortic pressure was estimated, and sucking condition was detected by the pressure sensor system. The blood flow was measured by the flow meter system within 10% error. As a result of these experiments, we confirmed the effectiveness of the sensor systems for SAH.

Biomagnetic Neurosensors. 3. Noninvasive Sensors Using Magnetic Stimulation and Biomagnetic Detection

A noninvasive biomagnetic sensor system that uses magnetic toroids for both neural stimulation and detection is described. It is shown that analytical signals obtained by direct magnetic detection (no signal averaging) compare favorably with electrical monitoring and that dose-response curves for local anesthetics correlate well between the two methods. Neural lifetimes are significantly extended when the noninvasive biomagnetic sensing system is used.

An optical sensor for the non-invasive measurement of the blood oxygen saturation of an artificial heart according to the variation of hematocrit

Abstract This study describes a non-invasive optical sensor and sensor system used to measure the blood oxygen saturation of an artificial heart, in vitro . The reflection type optical sensor consists of an LED for the light source and a PIN photodiode for the light detector in a flat pack. The emission wavelengths of the LED are 665 and 805 nm. The blood oxygen saturation was measured using the reflectance ratio of 665 to 805 nm. The sensor system for measurement of the oxygen saturation has been breadboarded. Changes in the blood oxygen saturation were detected by the developed sensor system in real time. The experimental set-up was designed to be identical in effects and circumstances to a living body. The non-invasive measurement of oxygen saturation in vitro was carried out. Using a constant volume (30 cc) of blood and various volumes (0, 10, 20, 30 cc) of a physical saline solution, the hematocrit level of the blood was determined. When the change in oxygen saturation is compared at each wavelength, the variation at 665 nm is four times more than at 805 nm. At the 805 nm wavelength there was only a small change over the 100-60% range of oxygen saturation. The reflectance ratio decreased with reduction of the hematocrit level. As the oxygen saturation was varied from 100 to 60%, the reflectance ratio R 805/ R 665 over the whole hematocrit range changed linearly.

Through a glass darkly: the lung as a window to monitor oxygen consumption, energy metabolism, and severity of critical illness

Medical diagnosis and therapeutic monitoring for critical illness require adaptation of laboratory analyses to the bedside. These are greatly helped by the modification of physiological and biochemical data-acquisition techniques to increase the number and accuracy of noninvasive variables that can be obtained from the patient. This paper addresses the choice of noninvasive measurements and is largely directed at the assessment of oxygen debt as a measure of the severity of ischemic and septic metabolic processes. Especially considered are those noninvasive measures of cardiorespiratory adequacy, key variables that need to be considered together with the metabolic function to adequately reflect the patient's state of accommodation to critical illness or injury. I describe a noninvasive sensor system linked to a computer work-station that functions in a pattern recognition mode to permit classification of patients as to the type and severity of their physiological adaptation. This system can serve as a sophisticated bedside monitor of the severity of the patient's condition, as a guide to therapy.