Search

This paper presents a phase fluorimetric sensor for the monitoring of the oxygen concentration in in vitro cell models. The sensing surface of the sensor consists of oxygen sensitive fluorescent dyes (platinum(II) octaethylporphyrinketone) embedded in a thin polystyrene film. In order to optimize the optical read-out scheme of the sensor, we carried out electromagnetic simulations of a fluorescently doped polystyrene film deposited on a glass-water interface. The simulation results showed highly anisotropic angular emission distribution with the maximum irradiance being at super critical angles, which attracts tailored optical designs to maximize the fluorescence collection efficiency. For this purpose, we applied an efficient optical read-out scheme based on an in-contact parabolic lens. The use of parabolic lens also facilitates confocal total internal reflection excitation from the substrate side. This makes the excitation effective and insensitive to biofouling or other optical changes in the sensing surface and, more importantly, greatly reduces the amount of excitation power radiated into the cell culture chamber. Experimental results show that when applied together with phase fluorimetric lifetime sensing, this optical scheme allows one to use thin films (<500 nm), dilute dye-polymer ratios (0.025%), low power LED excitation (<2 mW), and yet achieve over 40 dB signal-to-noise ratio at 10 Hz data rate at physiologically relevant oxygen concentrations. These features are important in cell studies, as the potential cytotoxicity of the dyes and the sensing method (i.e. the production of singlet oxygen) are mitigated by the low dye content and excitation power. In addition, thin and dilute polystyrene films are highly transparent and facilitate optical microscopy. We conclude the study by presenting experimental results where the device is applied together with on-line microscopy to an oxygen tension stress study of beating cardiomyocyte cultures. [ABSTRACT FROM AUTHOR]

Abstract: The methods needed to inductively read a passive resonance sensor in pressure measurement are studied. A simple dual-layer pressure sensor, a small portable phase response measurement unit and the methods to extract a coupling coefficient compensated resonance frequency are presented. The functionality and accuracy of the measurement are tested in a test rig and demonstrated in a realistic measurement environment. According to the test measurements, the overall performance of this wireless system is promising and the accuracy is within the typical range of the measurements made in the field of pressure garments. [Copyright &y& Elsevier]

Objectives : Facial nerve palsy causes blurred vision and ocular discomfort due to deficits in blinking and eye closure. The objective of this study was to determine whether eye-blinks could be elicited by electrical stimulation and whether electrically induced blink would have an effect on the visual acuity and ocular symptoms in patients with acute facial nerve palsy. Methods : The zygomatic branch of the facial nerve of fifteen participants with acute facial nerve palsy was electrically stimulated in order to elicit a blink. In successful cases, the participant proceeded with a two-hour TV watching session in which an electrically induced blink was delivered every 5 seconds. The control condition consisted of an otherwise similar TV watching session without electrically induced blinking. Subjective ocular symptoms were evaluated with a Dry Eye Questionnaire and visual acuity was assessed with a Logarithm of the Minimum Angle of Resolution (LogMAR) chart before and after both sessions. Results : The stimulation produced a blink in 8 participants (53%). The visual acuity in the affected eye decreased during the control session, whereas no significant change occurred during the stimulation session. The ocular symptoms were significantly reduced during the stimulation session. Conclusions : Electrically elicited blink is a promising method for reducing the eye symptoms in individuals with acute facial nerve palsy. [ABSTRACT FROM AUTHOR]

A non-contact real time pH measurement using fully modular optical parts is described for phenol-red medium cell cultures. The modular parts can be sterilized, and once the measurement is started at the beginning of culture, no recalibration or maintenance is needed till the end of the culture. Measurements can be carried out without any special manual attention. The modular assembly of LED and sensor cassettes is unique, robust, reusable and reproducible. pH is measured in an intact closed flow system, without wasting any culture medium. A special pump encapsulation enables the system to be effortlessly functional in extremely humid incubator environments. This avoids lengthy sample tubings in and out of the incubator, associated large temperature changes and CO 2 buffering issues. A new correction model to compensate errors caused e.g. by biolayers in spectrometric pH measurement is put-forward, which improves the accuracy of pH estimation significantly. The method provides resolution down to 0.1 pH unit in physiological pH range with mean absolute error 0.02. [ABSTRACT FROM AUTHOR]

Abstract: Nanostructures can show mechanical and electrical properties that differ from their bulk forms, and thus, precise experimental evaluation is needed when the structures are used in nanoelectronic devices or nanoelectromechanical systems. Ohm׳s law does not apply for nanostructures due to the various effects of size. It has been shown that due to surface scattering, the resistivity of the wire increases when the size decreases. This paper extends the studies and investigates how the resistive characteristics vary as the wire is stretched. An electrostatic actuating tensile device is applied and the resistive characteristics are evaluated in the frequency domain by means of maximum-length pseudo-random binary sequence (MLBS). The results reveal unreported characteristics of the applied nanowire; the resistance is increased as a function of stretching force. [Copyright &y& Elsevier]

A capacitive facial movement detection method designed for human–computer interaction is presented. Some point-and-click interfaces use facial electromyography for clicking. The presented method provides a contactless alternative. Electrodes with no galvanic coupling to the face are used to form electric fields. Changes in the electric fields due to facial movements are detected by measuring capacitances between the electrodes. A prototype device for measuring a capacitance signal affected by frowning and lifting eyebrows was constructed. A commercial integrated circuit for capacitive touch sensors is used in the measurement. The applied movement detection algorithm uses an adaptive approach to provide operation capability in noisy and dynamic environments. Experimentation with 10 test subjects proved that, under controlled circumstances, the movements are detected with good efficiency, but characterizing the movements into frowns and eyebrow lifts is more problematic. Integration with a two-dimensional (2D) pointing solution and further experiments are still required. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study was to show if pulse rise times (PRTs) extracted from photoplethysmographic (PPG) pulse waves (PWs) have an association with peripheral arterial disease (PAD) or its endovascular treatment, percutanoeus transluminal angioplasty (PTA) of the superficial femoral artery. Methods: Lower and upper limb PPG PWs were recorded and analyzed from 24 patients who suffered from PAD. The measurements were conducted before and after the treatment, and one month later by using transmission-mode PPG-probes placed in the index finger and second toe. Ankle-to-brachial pressure index and toe pressures were used as references in clinical patient measurements. PRTs, i.e., the time from the foot point to the peak point of the PW, were extracted from the PWs and compared bilaterally. The results from the PAD patients were also compared with 31 same-aged and 34 younger control subjects. Results: Statistically significant differences were found between the pretreatment PRTs of the treated limb of the PAD patients and the same-aged control subjects ($p< 10^{-9}$ , Mann–Whitney U-test). The changes in the PRT of the treated lower limb were observed immediately after the PTA ($p< 0.001$ , Student's t-test), and after one month ($p< 0.0005$), whereas the PRTs of the non-treated lower limb and upper limb did not indicate changes between different examinations. Conclusion: Results show that a PRT greater than 240 ms indicates PAD-lesions in the lower limb. Significance: This proof-of-concept study suggests that the PRT could be an effective and easy-to-use indicator for PAD and monitoring the effectiveness of its treatment. [ABSTRACT FROM AUTHOR]

Reanimation of paralysed facial muscles by electrical stimulation has been studied extensively in animal models, but human studies in this field are largely lacking. Twenty-four subjects with a peripheral facial nerve palsy with a median duration of three years were enrolled. We studied activations of four facial muscles with electrical stimulation using surface electrodes. In subjects whose voluntary movement was severely impaired or completely absent, the electrical stimulation produced a movement that was greater in amplitude compared with the voluntary effort in 10 out of 18 subjects in the frontalis muscle, in 5 out of 14 subjects in the zygomaticus major muscle, and in 3 out of 8 subjects in the orbicularis oris muscle. The electrical stimulation produced a stronger blink in 8 subjects out of 22 compared with their spontaneous blinks. The stimulation could produce a better movement even in cases where the muscles were clinically completely paretic, sometimes also in palsies that were several years old, provided that the muscle was not totally denervated. Restoring the function of paralysed facial muscles by electrical stimulation has potential as a therapeutic option in cases where the muscle is clinically paretic but has reinnervation. [ABSTRACT FROM AUTHOR]

Emotional reactions to basic, artificial, yet carefully controllable point-light displays (PLDs) were investigated with ratings of valence, arousal, approachability and dominance. PLDs were varied by movement location (upper and lower) and intensity (10°, 20° and 30° angular change) for angular upward and downward movements. Half of participants (N = 28) were told that PLDs were related to face while to other half nothing was hinted. Results showed that 20° and 30° angle lower location upward movements were rated as significantly more pleasant, relaxing and approachable than corresponding upper location downward movements. Informed participants rated 20° and 30° angle lower movements as significantly more controllable than corresponding upper movements. Results are important from many perspectives, like for understanding human perceptual mechanisms. When using PLDs only a small amount of information needs to be transmitted. This enables low bandwidth requirements. As PLD visualizations are simple, there is no need for high-definition displays. [ABSTRACT FROM AUTHOR]

Control of particle suspensions is needed in several modern industrial processes. A reason for the difficulty in this task has been the lack of a fast and reliable measurement. In this study, we tested the measurement of particle suspension by using a method based on a passive resonance sensor. The relative amounts of dispersing agent and aluminium oxide in the suspension were varied. The studied method yielded signals which depended on the complex permittivity of the suspension. The results indicated that we were able to measure information that can be used as feedback for the suspension preparation process. In addition, the tested instrumentation was simple and robust and thus this method may allow online measurements directly from the industrial processes. [ABSTRACT FROM AUTHOR]

Background Although clinical applications such as emergency medicine and prehospital care could benefit from a fast-mounting electroencephalography (EEG) recording system, the lack of specifically designed equipment restricts the use of EEG in these environments. Methods This paper describes the design and testing of a six-channel emergency EEG (emEEG) system with a rapid preparation time intended for use in emergency medicine and prehospital care. The novel system comprises a quick-application cap, a device for recording and transmitting the EEG wirelessly to a computer, and custom software for displaying and streaming the data in real-time to a hospital. Bench testing was conducted, as well as healthy volunteer and patient measurements in three different environments: a hospital EEG laboratory, an intensive care unit, and an ambulance. The EEG data was evaluated by two experienced clinical neurophysiologists and compared with recordings from a commercial system. Results The bench tests demonstrated that the emEEG system's performance is comparable to that of a commercial system while the healthy volunteer and patient measurements confirmed that the system can be applied quickly and that it records quality EEG data in a variety of environments. Furthermore, the recorded data was judged to be of diagnostic quality by two experienced clinical neurophysiologists. Conclusions In the future, the emEEG system may be used to record high-quality EEG data in emergency medicine and during ambulance transportation. Its use could lead to a faster diagnostic, a more accurate treatment, and a shorter recovery time for patients with neurological brain disorders. [ABSTRACT FROM AUTHOR]

A capacitive facial movement detection method designed for human-computer interaction is presented. Some point-and-click interfaces use facial electromyography for clicking. The presented method provides a contactless alternative. Electrodes with no galvanic coupling to the face are used to form electric fields. Changes in the electric fields due to facial movements are detected by measuring capacitances between the electrodes. A prototype device for measuring a capacitance signal affected by frowning and lifting eyebrows was constructed. A commercial integrated circuit for capacitive touch sensors is used in the measurement. The applied movement detection algorithm uses an adaptive approach to provide operation capability in noisy and dynamic environments. Experimentation with 10 test subjects proved that, under controlled circumstances, the movements are detected with good efficiency, but characterizing the movements into frowns and eyebrow lifts is more problematic. Integration with a two-dimensional (2D) pointing solution and further experiments are still required. [ABSTRACT FROM AUTHOR]

Background: Although clinical applications such as emergency medicine and prehospital care could benefit from a fast-mounting electroencephalography (EEG) recording system, the lack of specifically designed equipment restricts the use of EEG in these environments.Methods: This paper describes the design and testing of a six-channel emergency EEG (emEEG) system with a rapid preparation time intended for use in emergency medicine and prehospital care. The novel system comprises a quick-application cap, a device for recording and transmitting the EEG wirelessly to a computer, and custom software for displaying and streaming the data in real-time to a hospital. Bench testing was conducted, as well as healthy volunteer and patient measurements in three different environments: a hospital EEG laboratory, an intensive care unit, and an ambulance. The EEG data was evaluated by two experienced clinical neurophysiologists and compared with recordings from a commercial system.Results: The bench tests demonstrated that the emEEG system's performance is comparable to that of a commercial system while the healthy volunteer and patient measurements confirmed that the system can be applied quickly and that it records quality EEG data in a variety of environments. Furthermore, the recorded data was judged to be of diagnostic quality by two experienced clinical neurophysiologists.Conclusions: In the future, the emEEG system may be used to record high-quality EEG data in emergency medicine and during ambulance transportation. Its use could lead to a faster diagnostic, a more accurate treatment, and a shorter recovery time for patients with neurological brain disorders. [ABSTRACT FROM AUTHOR]