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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]

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 (p < 10^-4 ) and 0.79 (p < 10^-4 ), 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

The intensity measurement of facial muscle activity can be used in several applications such as human–computer interaction and behavioral science. A new method for the intensity measurement is presented. It is based on a contactless, capacitive measurement of the movements that the facial activity produces. The muscles responsible for raising the eyebrows, lowering the eyebrows, raising the mouth corners, and pulling down the mouth corners are measured simultaneously with the capacitive method and electromyography (EMG) during controlled experiments. Each muscle is activated by 10 participants at three different intensity levels (low, medium, and high), 10 repetitions at each level. The capacitive intensity values are in good agreement with the ones registered with the EMG: average mean absolute errors are between 7% and 12% of the observed intensity range. However, compared with the EMG, the capacitive intensity values are noticed to have offsets that may be partly caused by the measurement itself and partly by the EMG reference. As a result, the measurement may require a calibration for more intensity values than just the maximum. In the capacitive method, it is also required to distinguish between the muscle activations originating from the same facial regions to determine which activation is taking place. This is done with an almost perfect performance by using hierarchical clustering to cluster the intensity values. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]