When it comes to monitoring human health, accuracy is not a choice. Accuracy in blood pressure (BP) estimation is essential for proper diagnosis and management of hypertension. An error of 5 mmHg is so serious, it can be responsible for doubling or halving number of patients diagnosed with hypertension. Motion artifacts are external sources of inaccuracy and can be due to sudden arm motion, muscle tremor, shivering, and transport vehicle vibration. Medium term drift, due to changing environmental factors, such as ambient temperature, can also contribute to the inaccuracy. Long term drift (ageing), can reach 9 mmHg during the first three months of usage. In this thesis, a new stage is added to current cuff based BP devices. This stage is responsible for adjusting the pressure reading before displaying it to end users. The proposed stage is provided with a 3-axis accelerometer, which makes the detection of motion artifacts during measurement possible. Moreover, it monitors changes in the ambient temperature and sensor ageing, so that it will adaptively compensate for these inaccuracies. These sources of inaccuracy are suppressed using algorithms based on Empirical Mode Decomposition (EMD), which has the feature of removing unwanted noise components little effect on the phase or the frequency distribution of the measured signal. With motion artifacts, measurements show that the proposed algorithms considerably improved the accuracy of the blood pressure estimates in comparison with the commonly-used conventional oscillometric algorithm that does not include a stage for artifact suppression, and allowed the estimates to consistent with the international ANSI/AAMI/ISO standard. Moreover, simulations based on experimental results show that the system is able to compensate for drift due to temperature changes and ageing with excellent performance. Results show promise towards building a robust BP monitor, with very low errors due to motion artifacts, environmental changes, and ageing.

The new approach for motion artifact suppression in optical action potential records is presented in this thesis. Presented approach is based on independent component analysis utilization. Efficiency of proposed approach is evaluated here as well as its comparison with state of the art motion artifact suppression approaches.

The research related to designing portable monitoring devices for physiological signals has been at its peak in the last decade or two. One of the main obstacles in building such devices is the effect of the subject's movements on the quality of the signal. There have been numerous studies addressing the problem of removing motion artifact from the electrocardiogram (ECG) and photoplethysmography (PPG) signals in the past few years. However, no such study exists for the Impedance Plethysmography (IP) signal. The IP signal can be used to monitor respiration in mobile devices. However, it is very susceptible to motion artifact. The main aim of this dissertation is to develop adaptive and non-adaptive filtering algorithms to address the problem of motion artifact reduction from the IP signal.

"A wireless wearable battery-operated pulse oximeter has been developed in our laboratory for field triage applications. The wearable pulse oximeter, which uses a forehead-mounted sensor to provide arterial oxygen saturation (SpO2) and heart rate (HR) information, would enable field medics to monitor vital physiological information following critical injuries, thereby helping to prioritize life saving medical interventions. This study was undertaken to investigate if accelerometry (ACC)-based adaptive noise cancellation (ANC) is effective in minimizing SpO2 and HR errors induced during jogging to simulate certain motion artifacts expected to occur in the field. Preliminary tests confirmed that processing the motion corrupted photoplethysmographic (PPG) signals by simple Least-Mean-Square (LMS) and Recursive Least-Squares (RLS) ANC algorithms can help to improve the signal-to-noise ratio of motion-corrupted PPG signals, thereby reducing SpO2 and HR errors during jogging. The study showed also that the degree of improvement depends on filter order. In addition, we found that it would be more feasible to implement an LMS adaptive filter within an embedded microcontroller environment since the LMS algorithm requires significantly less operations."

Purpose: Intravaginal probes used for recording electromyography (EMG) from the pelvic floor muscles (PFMs) likely record activity from nearby muscles (crosstalk), and move during functional tasks, causing motion artifact data contamination, threatening the validity of results obtained. This study investigated the test-retest reliability and validity of surface EMG recordings from the PFMs using a novel, theoretically superior electrode in comparison to a commercially available intravaginal probe, the FemiscanTM. Methods: Healthy subjects (n=20) performed tasks with each vaginal electrode in situ: i) PFM maximal voluntary contractions (MVC), ii) coughs, iii) unilateral hip adductor/external rotator contractions at 25%MVC, 50%MVC, and MVC while keeping the PFMs relaxed or maximally contracted, and iv) transversus abdominis contractions (TrA; recorded using fine-wires) at 25%MVC, 50%MVC, MVC. Analyses: i) Intraclass correlation coefficients (ICC), ii) t-tests of proportions (α=0.05), iii) repeated measures ANOVAs and Tukey’s post-hoc testing (α=0.05) and iv) cross-correlation functions between peaks of transversus abdominis and PFM activity were used to determine the between-trial and between-day reliability of each vaginal electrode, a difference in prevalence of motion artifact contamination between electrodes, and the presence of crosstalk from the hip and TrA, respectively. Results: Between-trial reliability of both vaginal electrodes was excellent (ICC(3,1)=0.943-0.974). Between-day reliability was less consistent (ICC(3,1)=0.788-0.924 and 0.648-0.715 for the FemiscanTM and novel electrode, respectively). No significant difference in the proportion of files contaminated with motion artifact using each electrode existed. At submaximal intensities of hip muscle contractions, the FemiscanTM recorded significantly higher EMG amplitudes compared to what it recorded when the hip was relaxed, whereas the novel electrode did not, indicating that the FemiscanTM recorded crosstalk from the hip musculature. Low cross-correlation coefficients (<0.90) and large time delays (≥ 0.5 milliseconds) between peaks of PFM and TrA activity indicated that neither vaginal electrode recorded crosstalk from the TrA. Conclusion: The novel electrode is a promising tool to record EMG from the PFMs, as it records less crosstalk from the hip musculature than current technology while maintaining a high degree of reliability when comparing results collected within the same session; however, this electrode should not be used to compare one’s muscle activity between days. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2011-02-07 14:46:30.811

Although steady progress has been made towards the development of a wearable pulse oximeter to aid in remote physiological status monitoring (RPSM) and triage operations, the ability to extract accurate physiological data from a forehead pulse oximeter during extended periods of activity and in the presence of pressure disturbances acting on the sensor remains a significant challenge. This research was undertaken to assess whether the attachment method used to secure a pulse oximeter sensor affects arterial oxygen saturation (SpO2) and heart rate (HR) accuracy during motion. Additionally, two sensor housings were prototyped to assess whether isolating the sensor from external pressure disturbances could improve SpO2 and HR accuracy. The research revealed that measurement accuracy during walking is significantly affected by the choice of an attachment method. Specifically, the research indicated that an elastic band providing a contact pressure of 60 mmHg can result in decreased measurement error and improved reliability. Furthermore, the research validated that the two isolating housings we have investigated improve SpO2 and HR errors significantly at pressures as high as 1200 mmHg (160 kPa) compared to current commercial housings. This information may be helpful in the design of a more robust pulse oximeter sensor for use in RPSM.

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Mechanomyography (MMG) has been proposed as a control modality for alternative access technologies for individuals with disabilities. However, MMG recordings are highly susceptible to contamination from limb movements. Pressure-based transducers are touted to be the most robust to external movement although there is some debate about their optimal chamber geometry, in terms of low frequency gain and spectral flatness. To investigate the question of preferred geometry, transducers with varying chamber shapes were designed, manufactured and tested. The best performance was achieved with a transducer consisting of a low-frequency MEMS microphone, a 4 micron thick aluminized mylar membrane and a rigid conical chamber 7 mm in diameter and 5 mm in height. Furthermore, microphone-derived MMG spectra were found to be less influenced by motion artifact than corresponding accelerometer-derived spectra. However, artifact harmonics were present in both spectra, suggesting that bandpass filtering may not remove artifact influences permeating into MMG frequency bands.

Mechanomyography (MMG) has been proposed as a control modality for alternative access technologies for individuals with disabilities. However, MMG recordings are highly susceptible to contamination from limb movements. Pressure-based transducers are touted to be the most robust to external movement although there is some debate about their optimal chamber geometry, in terms of low frequency gain and spectral flatness. To investigate the question of preferred geometry, transducers with varying chamber shapes were designed, manufactured and tested. The best performance was achieved with a transducer consisting of a low-frequency MEMS microphone, a 4 micron thick aluminized mylar membrane and a rigid conical chamber 7 mm in diameter and 5 mm in height. Furthermore, microphone-derived MMG spectra were found to be less influenced by motion artifact than corresponding accelerometer-derived spectra. However, artifact harmonics were present in both spectra, suggesting that bandpass filtering may not remove artifact influences permeating into MMG frequency bands.