Parkinson's disease detection from 20-step walking tests using inertial sensors of a smartphone: Machine learning approach based on an observational case-control study

Parkinson's disease (PD) is a neurodegenerative disease inducing dystrophy of the motor system. Automatic movement analysis systems have potential in improving patient care by enabling personalized and more accurate adjust of treatment. These systems utilize machine learning to classify the movement properties based on the features derived from the signals. Smartphones can provide an inexpensive measurement platform with their built-in sensors for movement assessment. This study compared three feature selection and nine classification methods for identifying PD patients from control subjects based on accelerometer and gyroscope signals measured with a smartphone during a 20-step walking test. Minimum Redundancy Maximum Relevance (mRMR) and sequential feature selection with both forward (SFS) and backward (SBS) propagation directions were used in this study. The number of selected features was narrowed down from 201 to 4-15 features by applying SFS and mRMR methods. From the methods compared in this study, the highest accuracy for individual steps was achieved with SFS (7 features) and Naive Bayes classifier (accuracy 75.3%), and the second highest accuracy with SFS (4 features) and k Nearest neighbours (accuracy 75.1%). Leave-one-subject-out cross-validation was used in the analysis. For the overall classification of each subject, which was based on the majority vote of the classified steps, k Nearest Neighbors provided the most accurate result with an accuracy of 84.5% and an error rate of 15.5%. This study shows the differences in feature selection methods and classifiers and provides generalizations for optimizing methodologies for smartphone-based monitoring of PD patients. The results are promising for further developing the analysis system for longer measurements carried out in free-living conditions

Recent development of respiratory rate measurement technologies

Respiratory rate (RR) is an important physiological parameter whose abnormity has been regarded as an important indicator of serious illness. In order to make RR monitoring simple to do, reliable and accurate, many different methods have been proposed for such automatic monitoring. According to the theory of respiratory rate extraction, methods are categorized into three modalities: extracting RR from other physiological signals, RR measurement based on respiratory movements, and RR measurement based on airflow. The merits and limitations of each method are highlighted and discussed. In addition, current works are summarized to suggest key directions for the development of future RR monitoring methodologies

The 2023 wearable photoplethysmography roadmap

Photoplethysmography is a key sensing technology which is used in wearable devices such as smartwatches and fitness trackers. Currently, photoplethysmography sensors are used to monitor physiological parameters including heart rate and heart rhythm, and to track activities like sleep and exercise. Yet, wearable photoplethysmography has potential to provide much more information on health and wellbeing, which could inform clinical decision making. This Roadmap outlines directions for research and development to realise the full potential of wearable photoplethysmography. Experts discuss key topics within the areas of sensor design, signal processing, clinical applications, and research directions. Their perspectives provide valuable guidance to researchers developing wearable photoplethysmography technology

Piirilevylle liitettyjen pintaliitoskomponenttien taivutuskestävyys

Tässä kandidaatintyössä tutkittiin QFN- ja BGA-pintaliitoskomponenttien (Quad Flat No Leads ja Ball Grid Array) ja pintaliitoskondensaattorin jalkojen sekä juoteliitosten luotettavuutta taivutustestillä. QFN-komponentin rakenteita tutkittiin valmistamalla poikkileikkaus komponentista ja kuvaamalla sitä valomikroskoopilla sekä SEM/EDS-laitteistolla (pyyhkäisyelektroni-mikroskooppi/energiadispersiivinen spektrometri). QFN-komponentin datalehden ja SEM/EDS-tutkimusten perusteella laadittiin 3D-malli COMSOL Multiphysics® -ohjelmistolla. Simuloinnissa 3D-mallia kuormitettiin standardin mukaisella tavalla taivuttamalla kolmesta pisteestä. Testi toistettiin konkreettisena testinä standardin mukaisella taivutuslaitteella BGA-pintaliitoskomponentille ja kuudelle pintaliitoskondensaattorille. Simulaation tulokset osoittavat, että QFN-pintaliitoskomponentti ei kestäisi taivutusta. Suurimmat rasitukset kohdistuivat komponentin kulmissa sijaitseviin liitäntöihin, joissa myötörajat ylittyivät. Taivutustestissä BGA-komponentin sähkönjohtavuus ei muuttunut taivuttamisen aikana. Pintaliitoskondensaattorin kapasitanssi taas tippui huomattavasti taivutuksessa eikä enää palautunut lähtöarvoihin. Testi rikkoi kondensaattorin rakenteita, jolloin sen sähköiset ominaisuudet heikkenivät.In this thesis the reliability of terminals and connections of a QFN and BGA surface-mount device (Quad Flat No Leads and Ball Grid Array) and a surface-mount capacitor are measured in a bending test. The structure of the QFN-component was studied by preparing a cross section of the component and using an optical microscope and SEM/EDS equipment (scanning electron microscope / energy dispersive spectrometer). Measures collected from QFN datasheet and the data from SEM/EDS analysis were used to create a 3D model with COMSOL Multiphysics® -software. The model was stressed the way defined in an IEC standard from three points. The test was then repeated as a physical test for the BGA component and for six surface-mount capacitors using a standard test jig. The result of the simulation show that the QFN component would not withstand the stress and that the largest stresses are focused on the terminals and the connections in the corners of the component, where the yield strengths are exceeded. The electrical conductivity of the BGA component was not changed during the bending. When bending the capacitor there was a noticeable drop in the capacitance and the capacitance never returned to the original state. The test broke structures of the capacitor, hindering its electrical properties

Day-to-day repeatability of the results of the finger-toe-plot analysis

Non-invasive arterial pulse wave (PW) measurement provides valuable information on the vascular health. The aim of the study is to characterize the between-visit or day-to-day repeatability of combined finger and toe photoplethysmographic (PPG) signal analysis method called finger-toe plot (FT-plot) and compare it with the repeatability of other methods proposed for vascular characterization. Ten 22–36-year-old subjects were examined on 3 different days in order to find out the day-to-day repeatability of the results. The repeatability of the extracted parameters was analyzed by means of intra-class correlation coefficients (ICC) and free-marginal multirater κ agreement. ICCs varied widely from below 0.2 to almost 0.9, but κ coefficients higher than 0.7 were achieved for most of the results. Based on the presented results, the FT-plot analysis has at least sufficient day-to-day repeatability. However, further studies with real patients and different stages of cardiovascular diseases are required for confirming the findings.acceptedVersionPeer reviewe

Direct measurement of contraction force in cardiac tissue construct in 2D- plane using dual axis cantilever sensor

acceptedVersionPeer reviewe

Recovery characteristics of different tube materials in relation to combustion products

Common challenge in gas analyzers such as Ion Mobility Spectrometers (IMS) integrated into a measurement system is the reduced analysis speed that is partially limited by the temporal carry-over of sample molecules. It is caused by adsorption and absorption of the molecules into the gas tubes of the analyzer. We studied the recovery times of common tube materials: polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyethylene (PE), steel 316 L, parylene C coated steel and Silconert® coated steel from organic combustion products. The tests were performed in two temperatures, at 25 °C and at 70 °C. In addition, detailed analysis was performed for PTFE tube material at 33, 50, 70 and 100 °C to observe the temperature relation of desorption. Uncoated steel was found to have the best performance in increased temperature applications due lack of absorption. Major advantages from coatings compared to plane steel were not found. Plastics were found suitable materials in lower temperatures where adsorption exceeds absorption.publishedVersionPeer reviewe

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

OBJECTIVE: In this study, we propose a method for finding&#13: atherosclerotic changes based on the ratios of areas under peripheral arterial pulse&#13: wave (PW) contours and analyze its performance.APPROACH: The PW signals&#13: were recorded with force sensors and photoplethysmographic sensors from ankle,&#13: wrist, cubital fossa, index finger and second toe from 30 atherosclerotic patients&#13: and 52 control subjects. In addition, day-to-day repeatability of the method&#13: was studied with 10 test subjects examined on 3 different days. The ratios of&#13: areas under the PWs were computed and the results were evaluated by means&#13: of receiver operating characteristic (ROC) analysis, intra-class correlation (ICC)&#13: coefficient and multiple linear regression analysis.MAIN RESULTS: Areas under&#13: ROC curves of 0.802-0.906 were found for different area ratios having statistically&#13: significant differences between the atheroslerotic group and control groups. ICCs&#13: over 0.80 were found widely for the beat-by-beat analyzed data and over 0.95 for&#13: the data based on the averages over different numbers of PWs. Multiple linear&#13: regression analysis showed linear dependence between the area ratios and age&#13: and the diagnosis of atherosclerosis.SIGNIFICANCE: Our findings may facilitate&#13: development of novel diagnostic approaches and preventive strategies against&#13: cardiovascular disorders. However, further studies are needed to confirm the&#13: results. The presented study demonstrates the potential of arterial PW analysis&#13: in finding vascular abnormalities.&#13.acceptedVersionPeer reviewe