Electrically Induced Blink for the Prevention of Ocular Symptoms and Blurred Vision in Patients With Acute Facial Nerve Palsy.

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.

Covalent immobilization of luminescent oxygen indicators reduces cytotoxicity.

Luminescence-based oxygen sensing is a widely used tool in cell culture applications. In a typical configuration, the luminescent oxygen indicators are embedded in a solid, oxygen-permeable matrix in contact with the culture medium. However, in sensitive cell cultures even minimal leaching of the potentially cytotoxic indicators can become an issue. One way to prevent the leaching is to immobilize the indicators covalently into the supporting matrix. In this paper, we report on a method where platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin (PtTFPP) oxygen indicators are covalently immobilized into a polymer matrix consisting of polystyrene and poly(pentafluorostyrene). We study how the covalent immobilization influences the sensing material's cytotoxicity to human induced pluripotent stem cell-derived (hiPSC-derived) neurons and cardiomyocytes (CMs) through 7-13 days culturing experiments and various viability analyses. Furthermore, we study the effect of the covalent immobilization on the indicator leaching and the oxygen sensing properties of the material. In addition, we demonstrate the use of the covalently linked oxygen sensing material in real time oxygen tension monitoring in functional hypoxia studies of the hiPSC-derived CMs. The results show that the covalently immobilized indicators substantially reduce indicator leaching and the cytotoxicity of the oxygen sensing material, while the influence on the oxygen sensing properties remains small or nonexistent.

Effect of pulse waveforms on movement amplitudes and perceived discomfort in electric muscle stimulation in unresolved facial nerve palsy.

Studies on the effects of the pulse waveform used in electrical muscle stimulation on the activations and perceived discomfort of the waveform have been mainly executed on limb muscles with variable results, however, knowledge of these effects on facial muscles is currently lacking. We studied two waveforms, square wave and sinusoidal wavelet, for the activation of the frontalis muscle in 9 individuals with unresolved facial nerve palsy. Both waveforms produced a movement that was greater in amplitude compared with the maximal voluntary movement of the affected side in 8 participants and at least as great as the healthy side's maximal voluntary movement in 4 participants. Both waveforms were equally successful in producing movements, and there was no significant difference in perceived discomfort ratings between the two waveforms. These findings will be useful for the future development of neuroprosthetic applications for reanimating facial muscles using electrical stimulation. Trial registration: ClinicalTrials.gov NCT03496025, registration date March 19, 2018.

Facial muscle reanimation by transcutaneous electrical stimulation for peripheral facial nerve palsy.

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.

Lower Limb Pulse Rise Time as a Marker of Peripheral Arterial Disease.

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 ( , Mann-Whitney U-test). The changes in the PRT of the treated lower limb were observed immediately after the PTA ( , Student's t-test), and after one month ( ), 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.

Effects of Percutaneous Transluminal Angioplasty of Superficial Femoral Artery on Photoplethysmographic Pulse Transit Times.

We analyze the changes in upper and lower limb pulse transit times (PTT) caused by peripheral artery disease (PAD) and its treatment with percutaneous transluminal angioplasty (PTA) of the superficial femoral artery. PTTs were extracted from the photoplethysmograms (PPG) recorded from an index finger and 2nd toes. PTTs were defined between the R-peaks of the ECG and different reference points of the PPG: foot and peak points, maxima of 1st and 2nd derivative, and by means of intersecting tangents method. Also the PTTs between the toe and finger pulses were analyzed. Our sample consists of 24 subjects examined before and after the PTA and in 1-month follow-up visit. Also 28 older than 65 years controls having normal ankle-to-brachial pressure index (ABI) and no history in cardiovascular diseases as well as 21 younger subjects were examined. The differences between the groups and pre- and post-treatment phases were analyzed by means of non-parametric statistical tests. The changes in the PTTs of upper limb and non-treated lower limb were negligible. The agreement with the reference values, ABI and toe pressures, was studied by kappa-analysis, resulting in kappa-values of 0.33-0.91. Differences in PTTs were found between pre-treatment state of the treated limb, post-treatment state and the follow-up visit, as well as between the pre-treatment state and controls. If patients' age and systolic blood pressure were taken into consideration, the method of lower limb PTT calculation from the peak point turns out feasible in finding the markers of PAD and monitoring post-treatment vascular remodellation.

A Portable Microscale Cell Culture System with Indirect Temperature Control.

A physiologically relevant environment is essential for successful long-term cell culturing in vitro. Precise control of temperature, one of the most crucial environmental parameters in cell cultures, increases the fidelity and repeatability of the experiments. Unfortunately, direct temperature measurement can interfere with the cultures or prevent imaging of the cells. Furthermore, the assessment of dynamic temperature variations in the cell culture area is challenging with the methods traditionally used for measuring temperature in cell culture systems. To overcome these challenges, we integrated a microscale cell culture environment together with live-cell imaging and a precise local temperature control that is based on an indirect measurement. The control method uses a remote temperature measurement and a mathematical model for estimating temperature at the desired area. The system maintained the temperature at 37±0.3 °C for more than 4 days. We also showed that the system precisely controls the culture temperature during temperature transients and compensates for the disturbance when changing the cell cultivation medium, and presented the portability of the heating system. Finally, we demonstrated a successful long-term culturing of human induced stem cell-derived beating cardiomyocytes, and analyzed their beating rates at different temperatures.

The effect of percutaneous transluminal angioplasty of superficial femoral artery on pulse wave features.

We aimed to analyze the effects of percutaneous transluminal angioplasty (PTA) of the superficial femoral artery (SFA) on arterial pulse waves (PWs). Altogether 24 subjects i.e. 48 lower limbs were examined including 26 treated lower limbs having abnormal ankle-to-brachial pressure index (ABI) (ABI<0.9 or ABI>1.3) and 22 non-treated lower limbs. The measurements were conducted in pre-, peri- and post-treatment phases as well as in follow-up visit after 1 month. Both ABI and toe pressures measured by standard equipment were used as reference values. PW-derived parameters include ratios of different peaks of the PW and time differences between them as well as aging index. Both treated and non-treated limbs were compared in pre- and post-treatment as well as follow-up visit conditions. The results were evaluated in terms of statistical tests, Bland-Altman-plots, free-marginal multirater κ-analysis and multiple linear regression analysis. PTA was found to cause small changes to the studied PW-derived parameters of the treated limb which were observed immediately after the treatment, but the changes were more pronounced in the follow-up visit. In addition, we observed that the endovascular instrumentation itself does not cause significant changes to the PW-derived parameters. The results show that PW-analysis could be a useful tool for monitoring the treatment-effect of the PTA. However, because the pre-treatment differences of the treated and non-treated limb were small, further studies with subjects having no arterial diseases are required. The study demonstrates the potential of the PW analysis in monitoring vascular abnormalities.

Parameters Extracted From Arterial Pulse Waves as Markers of Atherosclerotic Changes: Performance and Repeatability.

Arterial diseases are significant and increasing cause of mortality and morbidity. In this study, we analyze and compare the discrimination capability of different arterial pulse wave (PW) based indices, both earlier proposed and novel ones, for describing the vascular health. The repeatability of the indices is also evaluated. Both volume PWs and dynamic pressure PWs are recorded by using photoplethysmographic and electromechanical film (EMFi) sensors connected to a wireless body sensor network. The study population consists of 82 subjects, 30 atherosclerotic patients, and 52 control subjects. In addition, day-to-day variability of the derived indices is studied with ten test subjects examined on three different days. The results are evaluated in terms of statistical tests and receiver operating characteristic (ROC) curves as well as coefficient of variation (CV) and intraclass correlation coefficient (ICC). Altogether 24 out of the evaluated 40 PW parameters showed statistical differences ( or less) between controls and atherosclerotic patients. Maximum area under curve was 0.88. Most of the indices had ICCs higher than 0.8 and average CVs less than 0.1. The study shows that the amplitude ratios and time intervals between different PW peaks could be a useful additional tool for the detection of atherosclerosis. The results encourage us for further studies in this field. Up to our knowledge, the performance and the repeatability of different PW derived indices have previously not been studied and compared with each other this extensively. Our findings also provide evidence for the utility of PW measurements for the detection of atherosclerotic changes.

Areas under peripheral pulse waves: a potential marker of atherosclerotic changes.

OBJECTIVE: In this study, we propose a method for finding atherosclerotic changes based on the ratios of areas under peripheral arterial pulse wave (PW) contours and analyze its performance. APPROACH: The PW signals were recorded with force sensors and photoplethysmographic sensors from ankle, wrist, cubital fossa, index finger and second toe from 30 atherosclerotic patients and 52 control subjects. In addition, the day-to-day repeatability of the method was studied with 10 test subjects examined on three different days. The ratios of areas under the PWs were computed and the results were evaluated by means of receiver operating characteristic (ROC) analysis, intra-class correlation (ICC) coefficient and multiple linear regression analysis. MAIN RESULTS: Areas under ROC curves of 0.802-0.906 were found for different area ratios having statistically significant differences between the atheroslerotic group and control groups. ICCs over 0.80 were found widely for the beat-by-beat analyzed data and over 0.95 for the data based on the averages over different numbers of PWs. Multiple linear regression analysis showed linear dependence between the area ratios and age and the diagnosis of atherosclerosis. SIGNIFICANCE: Our findings may facilitate development of novel diagnostic approaches and preventive strategies against cardiovascular disorders. However, further studies are needed to confirm the results. The presented study demonstrates the potential of arterial PW analysis in finding vascular abnormalities.

Combining finger and toe photoplethysmograms for the detection of atherosclerosis.

In this study, we propose and analyze a noninvasive method for detecting the atherosclerotic changes of vasculature based on the analysis of photoplethysmographic (PPG) signals. METHODS: the proposed method is called finger-toe (FT)-plot analysis that utilizes both finger and toe PPG signals. For the features extracted from the FT-plots, we implemented different linear discriminant analysis based classifiers and analyzed seven promising ones in detail. We used the signals recorded from altogether 75 test subjects (categorized as 27 atherosclerotic patients and 48 control subjects based on ankle brachial pressure index, symptoms and disease history) in the training, and testing of the method. Besides leave one out cross validation, we tested the method by using training data independent signals recorded with two different PPG devices. The performance of the FT-plot is compared with other indicators related to the risk of cardiovascular diseases. RESULTS: we found an average area under ROC (receiver operating characteristic) curve of [Formula: see text] (mean ± standard deviation based on different datasets), sensitivity of [Formula: see text], specificity of [Formula: see text], accuracy of [Formula: see text], performance of [Formula: see text] and positive and negative predictive values of [Formula: see text] and [Formula: see text], respectively, for the different tested classifiers. CONCLUSIONS: the study shows that the FT-plot analysis could be a useful additional tool for detecting atherosclerotic changes. Our findings provide evidence for the utility of multi-channel pulse wave measurements and analysis for the detection of atherosclerosis. This may facilitate development of novel early diagnostic approaches and preventive strategies.

Age Dependence of Arterial Pulse Wave Parameters Extracted From Dynamic Blood Pressure and Blood Volume Pulse Waves.

Atherosclerosis is a significant cause of mortality in the aged population, and it affects arterial wall properties causing differences in measured arterial pulse wave (PW). In this study, both dynamic arterial blood pressure PWs and blood volume PWs are analyzed. The PWs are recorded noninvasively from multiple measurement points from the upper and lower limbs from 52 healthy (22-90-year-old) volunteers without known cardiovascular diseases. For each signal, various parameters earlier proposed in the literature are computed, and 25 different novel parameters are formed by combining these parameters. The results are evaluated in terms of age and heart rate (HR) dependence of the parameters. In general, the results show that 14 out of 25 tested combined parameters have stronger age dependence than any of the individual parameters. The highest obtained linear correlation coefficients between the age and combined parameter and individual parameter equal to 0.85 ( ) and 0.79 ( ), respectively. Most of the combined parameters have also improved discrimination capability when classifying the test subjects into different age groups. This is a promising result for further studies, but indicate that the age dependence of the parameters must be taken into account in further studies with atherosclerotic patients.

Optical non-contact pH measurement in cell culture with sterilizable, modular parts.

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 CO2 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.

Monitoring arterial pulse waves with synchronous body sensor network.

A wireless body sensor network for arterial pulse wave (PW) measurements is presented and tested with ten subjects. The system is capable of recording both mechanical PW contours with sensors made of a low-cost polypropylene-based material called electromechanical film (EMFi) and volume pulse signal with photoplethysmographic transducers. By using both types of sensors, the PW contours can be recorded from various locations. The system combined with automatic analysis methods enables to easily analyze the PW contours in order to obtain a more comprehensive view on the vascular health. To demonstrate this, two parameters used in literature, reflection index and radial augmentation index were calculated for the test subjects as a function of time. The results show that these parameter values may vary more than 20% in a period of 100 s, which suggests that a large number of PWs should be analyzed before making conclusions based on the calculated indices. In addition, the effects of the static bias force to the mechanical PW signal recorded with the EMFi sensors were studied. The PW signal with the maximum amplitude is obtained when the pressure caused by the static bias force corresponds to the contact pressure between typical systolic and diastolic blood pressures. The EMFi sensors used in the proposed system are a potential low-cost alternative for tonometric sensors in collecting data in the PW analysis for arterial screening.

Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors.

Silicon nanowire-based field-effect transistors (SiNW FETs) have demonstrated the ability of ultrasensitive detection of a wide range of biological and chemical targets. The detection is based on the variation of the conductance of a nanowire channel, which is caused by the target substance. This is seen in the voltage-current behavior between the drain and source. Some current, known as leakage current, flows between the gate and drain, and affects the current between the drain and source. Studies have shown that leakage current is frequency dependent. Measurements of such frequency characteristics can provide valuable tools in validating the functionality of the used transistor. The measurements can also be an advantage in developing new detection technologies utilizing SiNW FETs. The frequency-domain responses can be measured by using a commercial sine-sweep-based network analyzer. However, because the analyzer takes a long time, it effectively prevents the development of most practical applications. Another problem with the method is that in order to produce sinusoids the signal generator has to cope with a large number of signal levels. This may become challenging in developing low-cost applications. This paper presents fast, cost-effective frequency-domain methods with which to obtain the responses within seconds. The inverse-repeat binary sequence (IRS) is applied and the admittance spectroscopy between the drain and source is computed through Fourier methods. The methods is verified by experimental measurements from an n-type SiNW FET.

Novel wireless electroencephalography system with a minimal preparation time for use in emergencies and prehospital care.

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.

Night-time EKG and HRV monitoring with bed sheet integrated textile electrodes.

A system for unobtrusive night-time electrocardiogram (EKG) and heart rate variability (HRV) monitoring as well as data analysis methods are presented, comparing bed sheet HR and HRV values with corresponding parameters obtained by a reference measurement. Our system uses eight embroidered textile electrodes attached laterally to a bed sheet for measuring bipolar contact EKG from multiple channels. The electrodes are arranged in a line so that at least two adjacent electrodes make sufficient skin contact. The focus of the signal processing development has been on selecting the best measurement channel for further analysis and minimizing the amount of incorrectly detected R-peaks. The test measurements were performed with four healthy men without previously known cardiac disorders and one who frequently had premature ventricular contractions (ectopic beats). For healthy test subjects, an average of 94.9% heartbeat detection coverage was achieved with the system during 29 measurement nights (in total 213.8 h of data). In most cases, the quality of the signal obtained from bed sheet electrodes is good enough for the computer-assisted cardiac arrhythmia detection. Applications for EKG derived RR-interval data include the calculation of HRV parameters that can be utilized in sleep quality analysis and other wellness-related topics as well as sleep apnoea detection.

A wearable, wireless gaze tracker with integrated selection command source for human-computer interaction.

A light-weight, wearable, wireless gaze tracker with integrated selection command source for human-computer interaction is introduced. The prototype system combines head-mounted, video-based gaze tracking with capacitive facial movement detection that enable multimodal interaction by gaze pointing and making selections with facial gestures. The system is targeted mainly to disabled people with limited mobility over their hands. The hardware was made wireless to remove the need to take off the device when moving away from the computer, and to allow future use in more mobile contexts. The algorithms responsible for determining the eye and head orientations to map gaze direction to on-screen coordinates are presented together with the one to detect movements from the measured capacitance signal. Point-and-click experiments were conducted to assess the performance of the multimodal system. The results show decent performance in laboratory and office conditions. The overall point-and-click accuracy in the multimodal experiments is comparable to the errors in previous research on head-mounted, single modality gaze tracking that does not compensate for changes in head orientation.

Capacitive facial movement detection for human-computer interaction to click by frowning and lifting eyebrows: assistive technology.

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.

System for ECG and heart rate monitoring during group training.

We present a system for measuring ECG signals simultaneously from multiple persons during a group training session. The system transmits the signals to a coordinating computer where heart rate and other parameters are calculated from the signals. The heart rate values can then be shown for example through a video projector on a large display along with individual information about the training intensity.