shahbaz askari - Academia.edu (original) (raw)

Papers by shahbaz askari

2015 22nd Iranian Conference on Biomedical Engineering (ICBME), 2015

Decomposing the EMG signal and determining fiber's motor units is a challenging work in this ... more Decomposing the EMG signal and determining fiber's motor units is a challenging work in this area. The high amounts of resident noise and artifacts distort the signal. But, the decomposition gets more complicated, when we have motor unit action potential MUAP, interference during one channel recording. Considering this distortion, recognition and separation of motor units from each other, and determining the degree of their membership to each fiber gives valuable information. In this paper. First, motor units are determined and separated according to a set of filters similar to Gabor filters, then by extracting some different time-frequency and morphology features, the feature space will be determined. In the next step, the number of clusters which are the number of fibers will be determined. The clustering method used for this purpose is FCM clustering method. One of the innovations of the proposed method in this study is using an algorithm which improves the accuracy of the decomposition. This algorithm employs the membership information of each motor unit in fuzzy clustering along with the feature selection using mutual information of each motor unit. The results indicate 7.3% improvement while decreasing computational costs.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables IV

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables IV

Biology

The purpose of this study was to determine which thermometry technique is the most accurate for r... more The purpose of this study was to determine which thermometry technique is the most accurate for regular measurement of body temperature. We compared seven different commercially available thermometers with a gold standard medical-grade thermometer (Welch-Allyn): four digital infrared thermometers (Wellworks, Braun, Withings, MOBI), one digital sublingual thermometer (Braun), one zero heat flux thermometer (3M), and one infrared thermal imaging camera (FLIR One). Thirty young healthy adults participated in an experiment that altered core body temperature. After baseline measurements, participants placed their feet in a cold-water bath while consuming cold water for 30 min. Subsequently, feet were removed and covered with a blanket for 30 min. Throughout the session, temperature was recorded every 10 min with all devices. The Braun tympanic thermometer (left ear) had the best agreement with the gold standard (mean error: 0.044 °C). The FLIR One thermal imaging camera was the least acc...

Biology

The colour of the silicone enclosure of an implantable reflectance-based optical probe plays a cr... more The colour of the silicone enclosure of an implantable reflectance-based optical probe plays a critical role in sensor performance. Red-coloured probes that are highly reflective to near-infrared light have been found to increase photodetector power by a factor of 6 for wavelengths between 660 and 950 nm and triple the magnitude of measured cardiac pulsations compared to traditional black probes. The increase in photodetector power and cardiac pulsation magnitude is presumably due to increased spatial range resulting from a higher magnitude of superficial tissue scattering. Conversely, probes with highly absorbent colours such as black and blue result in more stable signals and are expected to have higher spatial resolution and depth of penetration.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables III, 2022

Background: We developed an implantable optical sensor based on near-infrared spectroscopy (NIRS)... more Background: We developed an implantable optical sensor based on near-infrared spectroscopy (NIRS) to continuously monitor spinal cord oxygenation and hemodynamics in patients with acute spinal cord injury (SCI). As a safety assessment measure, we aimed to study the effect of near-infrared (NIR) light emission and contact compression of the NIRS sensor on spinal cord tissue structure. Our previous in-vitro heat tests indicated no heat generation by the NIRS sensor. This study evaluated whether the NIRS sensor resulted in any potential compression damage to the spinal cord using histological analysis. Methods: Six Yucatan mini-pigs received a T10 SCI. A custom implantable NIRS sensor (version 2) was placed extradurally on the spinal cord and fixed with magnets and cross-connectors. After seven days of continuous data collection at 100Hz, the sensor was removed to allow for histological examination of the spinal cord tissue. Cellular damage was observed in the spinal cord at the NIRS sensor placement site in two animals. The design, shape, and material of the NIRS sensor were significantly revised to reduce the sensor footprint, minimize the compression on the cord, increase the sensor flexibility, and improve its clinical application. An in-vivo pilot experiment was performed on a Yucatan miniature pig with a T10 SCI to evaluate potential compression damage of the spinal cord tissue from placement and direct contact of the refined NIRS sensor (version 5). A fibrin sealant, TISSEEL, was utilized to fix the version 5 NIRS sensor on the spinal cord. Result: There were no signs of cellular damage, indentation, and significant flattening on the dorsal surface of the spinal cord where the version 5 NIRS sensor was placed for up to 4.5 hours. Conclusion: The refined NIRS sensor did not cause any compression damage to the porcine spinal cord after implantation for 4.5 hours. Implanting this sensor on the spinal cord of SCI patients requires further in-vivo examinations to ensure the sensor is safe to use for up to 14 days.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables III, 2022

The purpose of this study was to investigate the accuracy of infrared thermography for measuring ... more The purpose of this study was to investigate the accuracy of infrared thermography for measuring body temperature. We compared a commercially available infrared thermal imaging camera (FLIR One) with a medical-grade oral thermometer (Welch-Allyn) as a gold standard. Measurements using the thermal imaging camera were taken from both a short distance (10cm) and long distance (50cm) from the subject. Thirty young healthy adults participated in a study that manipulated body temperature. After establishing a baseline, participants lowered their body temperature by placing their feet in a cold-water bath for 30 minutes while consuming cold water. Feet were then removed and covered with a blanket for 30 minutes as body temperature returned to baseline. During the course of the 70-minute experiment, body temperature was recorded at a 10-minute interval. The thermal imaging camera demonstrated a significant temperature difference from the gold standard from both close range (mean error: +0.433°C) and long range (mean error: +0.522°C). Despite demonstrating potential as a fast and non-invasive method for temperature screening, our results indicate that infrared thermography does not provide an accurate measurement of body temperature. As a result, infrared thermography is not recommended for use as a fever screening device.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables III

Introduction: We previously developed an implantable near-infrared spectroscopy (NIRS) sensor to ... more Introduction: We previously developed an implantable near-infrared spectroscopy (NIRS) sensor to provide real-time monitoring of spinal cord oxygenation and hemodynamics in a porcine model of acute SCI. Here, we present a method to fix an improved design of the sensor to the spinal cord for up to 14-days post-injury which will be important for its clinical application. Methods: Two Yucatan mini-pigs received a T2 contusion-compression injury. A multi-wavelength NIRS system with a custom-made miniaturized sensor was laid over the dura. The NIRS sensor consisted of a five wavelength LED and photodetector from the previous design. The placement of the LED and photodetector was reconfigured to create a sensor with a slimmer shape. The sensor was mounted on a flexible printed circuit board (PCB) and enclosed by an implantable soft silicone with thin flaps on its side. This allowed the sensor to sit flush on the dura and secured with a fibrin sealant material (TISSEEL), eliminating the need for additional spinal fixation devices. The surgical incision was sutured closed, and the sensor was fixed on the spinal cord while the animal recovered for 14-days post-injury. A fluoroscopy was performed on the surgery day, 7- and 14-days post-injury to assess the positioning of the sensor. Results/Conclusion: The implantable NIRS sensor appeared to remain fixed on the spinal cord after 14-days post-injury upon analysis of fluoroscopy images and examining the re-exposed surgical wound. Securing the NIRS sensor to the spinal cord with a fibrin sealant may provide a method for fixation for up to 14-days post-injury.

Optical Diagnostics and Sensing XXII: Toward Point-of-Care Diagnostics

The Neuroscience Journal of Shefaye Khatam, 2018

Long term video electro-encephalographic (EEG) monitoring (LTM) is defined as the continuous and ... more Long term video electro-encephalographic (EEG) monitoring (LTM) is defined as the continuous and synchronized recording of EEG and multimedia to analyze brain abnormalities. A conventional LTM sys tem continuously records EEG in the frequency range of 0.5-70Hz. The data synchronization, the high-volume data management, the sys tem reliability as well as noise reduction remain significant challenges in an LTM machine. Moreover, online multiuser access to the data during the recording as well as online EEG control remains another essential point. Beyond conventional LTM sys tems, recent s tudies indicate the exis tence of a potentially clinically-relelvant near-DC field potential (f<0.1Hz) among the EEG data. This DC field potential, although sometimes present in healthy subjects, also appears to be associated with a variety of brain abnormalities such as migraines with auras and some types of epileptic activity. Therefore, the EEG frequency range mus t be extended to include lower...

OBJECTIVE Monitoring of the ultra-low frequency potentials, particularly cortical spreading depre... more OBJECTIVE Monitoring of the ultra-low frequency potentials, particularly cortical spreading depression (CSD), is excluded in epilepsy monitoring due to technical barriers imposed by the scalp ultra-low frequency electroencephalogram (EEG). As a result, clinical studies of CSD have been limited to invasive EEG. Therefore, the occurrence of CSD and its interaction with epileptiform field potentials (EFP) require investigation in epilepsy monitoring. METHODS Using a novel AC/DC-EEG approach, the occurrence of DC potentials in patients with intractable epilepsy presenting different symptoms of aura was investigated during long-term video-EEG monitoring. RESULTS Various forms of slow potentials, including simultaneous negative direct current (DC) potentials and prolonged EFP, propagated negative DC potentials, and non-propagated single negative DC potentials were recorded from the scalp of the epileptic patients. The propagated and single negative DC potentials preceded the prolonged EFP...

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables II

A newborn infant has an extraordinarily vulnerable and immature central nervous system, which is ... more A newborn infant has an extraordinarily vulnerable and immature central nervous system, which is undergoing rapid structural and functional development. As these infants are pre-verbal and their neurological systems are immature, assessing accurately and treating effectively procedure-related pain is a significant challenge. The nociceptive signals caused by the pain are accompanied by changes in regional blood oxygenation and neuronal activity in the infant’s brain. In this study, we developed a dual-mode Near-Infrared Spectroscopy (NIRS) and electroencephalography (EEG) monitor that can measure regional brain oxygenation and neuronal activity concurrently (safe and non-invasive). The neuronal activity is measured by an innovative low-noise EEG amplifier in both conventional and ultra-low frequency bandwidths. This multimodal recording allows us to investigate the coupling of neuronal activity and the neurovascular system as never before. NIRS and EEG electrodes are miniaturized and unified in one sensor. This modification facilitates the use of a NIRS/EEG device for recording from neonatal subjects. Ten infants, born between 27-35 weeks gestational age, are being recruited from the NICU at BCWH. They are monitored during a single, routine blood draw required for clinical care. In this experiment, we investigate the change of cerebral hemodynamic across 3 phases of blood collection, baseline, heel lance, recovery. Variation of blood flow accompanied with the slow shift of EEG has been detected during the pain stimulus phase. Additionally, the increase of gamma-band correlated to a rise in blood flow is also observed

According to the WHO, 15,000 children under five years are dying every day from preventable cause... more According to the WHO, 15,000 children under five years are dying every day from preventable causes with 80% of these children being born in low-income countries. Portable optical medical diagnostic devices can help physicians, nurses and untrained health workers to objectively identify children who are at a higher risk of dying. In the last 2 years, we collected the oxygenation values of the brachioradialis muscle, using a commercial Near Infrared Spectroscopy (NIRS) device, in 200 children under 5 years admitted in two hospitals in Uganda. Data revealed that the tissue oxygen saturation decrease during a vascular occlusion predicts children at higher risk better than other vital signs (SpO2, respiration rate, heart rate and temperature). Based on these results, we designed a low cost Continuous Wave Spatially Resolved NIRS device controlled by a smartphone in order to extend our study to a larger population and confirm our observation. The total cost of this device (excluding the s...

2014 21th Iranian Conference on Biomedical Engineering, Nov 1, 2014

We present an automated method for decomposing EMG signals into their components, motor-unit acti... more We present an automated method for decomposing EMG signals into their components, motor-unit action-potential (MUAP) trains based on short time Fourier transform STFT and wavelet transform. Since the number of MUAP classes composing the EMG signal, the number of MUAP’s per class, their firing pattern, and the expected shape of the MUAP waveforms are unknown, the decomposition of real EMG signals into their constituent MUAP’s and their classification into groups of similar shapes is a typical case of an unsupervised learning pattern recognition problem. The method is able to handle single- or multi-channel signals, recorded by concentric needle electrodes during low and moderate levels of muscular contraction. The method uses empirical features in STFT transform, shape and template of MU and CWT in order to decompose the signal to its original MUAP. Also the discrete wavelet transform has been acquired in early steps in order to eliminate the level of low amplitude noise in signal. W...

Neuroscience, 2016

Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pat... more Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pathophysiology of different neurological disorders. Yet, research into SD-related disorders has been hampered by the lack of non-invasive recording techniques of SD. Here we compared the manifestations of SD in continuous non-invasive electroencephalogram (EEG) recordings to invasive electrocorticographic (ECoG) recordings in order to obtain further insights into generator structures and electrogenic mechanisms of surface recording of SD. SD was induced by KCl application and simultaneous SD recordings were performed by scalp EEG as well as ECoG electrodes of somatosensory neocortex of rats using a novel homemade EEG amplifier, AgCl recording electrodes, and high chloride conductive gel. Different methods were used to analyze the data; including the spectrogram, bi-spectrogram, pattern distribution, relative spectrum power, and multivariable Gaussian fit analysis. The negative DC shifts recorded by scalp electrodes exhibited a high homogeneity to those recorded by ECoG electrodes. Furthermore, this novel method of recording and analysis was able to separate SD recorded by scalp electrodes from non-neuronal DC shifts induced by other potential generators, such as the skin, muscles, arteries, dura, etc. These data suggest a novel application for continuous non-invasive monitoring of DC potential changes, such as SD. Non-invasive monitoring of SD would allow early intervention and improve outcome in SDrelated neurological disorders.

Neuroscience, Oct 1, 2016

Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pat... more Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pathophysiology of different neurological disorders. Yet, research into SD-related disorders has been hampered by the lack of non-invasive recording techniques of SD. Here we compared the manifestations of SD in continuous non-invasive electroencephalogram (EEG) recordings to invasive electrocorticographic (ECoG) recordings in order to obtain further insights into generator structures and electrogenic mechanisms of surface recording of SD. SD was induced by KCl application and simultaneous SD recordings were performed by scalp EEG as well as ECoG electrodes of somatosensory neocortex of rats using a novel homemade EEG amplifier, AgCl recording electrodes, and high chloride conductive gel. Different methods were used to analyze the data; including the spectrogram, bi-spectrogram, pattern distribution, relative spectrum power, and multivariable Gaussian fit analysis. The negative DC shifts recorded by scalp electrodes exhibited a high homogeneity to those recorded by ECoG electrodes. Furthermore, this novel method of recording and analysis was able to separate SD recorded by scalp electrodes from non-neuronal DC shifts induced by other potential generators, such as the skin, muscles, arteries, dura, etc. These data suggest a novel application for continuous non-invasive monitoring of DC potential changes, such as SD. Non-invasive monitoring of SD would allow early intervention and improve outcome in SDrelated neurological disorders.

2015 22nd Iranian Conference on Biomedical Engineering (ICBME), 2015

Decomposing the EMG signal and determining fiber's motor units is a challenging work in this ... more Decomposing the EMG signal and determining fiber's motor units is a challenging work in this area. The high amounts of resident noise and artifacts distort the signal. But, the decomposition gets more complicated, when we have motor unit action potential MUAP, interference during one channel recording. Considering this distortion, recognition and separation of motor units from each other, and determining the degree of their membership to each fiber gives valuable information. In this paper. First, motor units are determined and separated according to a set of filters similar to Gabor filters, then by extracting some different time-frequency and morphology features, the feature space will be determined. In the next step, the number of clusters which are the number of fibers will be determined. The clustering method used for this purpose is FCM clustering method. One of the innovations of the proposed method in this study is using an algorithm which improves the accuracy of the decomposition. This algorithm employs the membership information of each motor unit in fuzzy clustering along with the feature selection using mutual information of each motor unit. The results indicate 7.3% improvement while decreasing computational costs.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables IV

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables IV

Biology

The purpose of this study was to determine which thermometry technique is the most accurate for r... more The purpose of this study was to determine which thermometry technique is the most accurate for regular measurement of body temperature. We compared seven different commercially available thermometers with a gold standard medical-grade thermometer (Welch-Allyn): four digital infrared thermometers (Wellworks, Braun, Withings, MOBI), one digital sublingual thermometer (Braun), one zero heat flux thermometer (3M), and one infrared thermal imaging camera (FLIR One). Thirty young healthy adults participated in an experiment that altered core body temperature. After baseline measurements, participants placed their feet in a cold-water bath while consuming cold water for 30 min. Subsequently, feet were removed and covered with a blanket for 30 min. Throughout the session, temperature was recorded every 10 min with all devices. The Braun tympanic thermometer (left ear) had the best agreement with the gold standard (mean error: 0.044 °C). The FLIR One thermal imaging camera was the least acc...

Biology

The colour of the silicone enclosure of an implantable reflectance-based optical probe plays a cr... more The colour of the silicone enclosure of an implantable reflectance-based optical probe plays a critical role in sensor performance. Red-coloured probes that are highly reflective to near-infrared light have been found to increase photodetector power by a factor of 6 for wavelengths between 660 and 950 nm and triple the magnitude of measured cardiac pulsations compared to traditional black probes. The increase in photodetector power and cardiac pulsation magnitude is presumably due to increased spatial range resulting from a higher magnitude of superficial tissue scattering. Conversely, probes with highly absorbent colours such as black and blue result in more stable signals and are expected to have higher spatial resolution and depth of penetration.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables III, 2022

Background: We developed an implantable optical sensor based on near-infrared spectroscopy (NIRS)... more Background: We developed an implantable optical sensor based on near-infrared spectroscopy (NIRS) to continuously monitor spinal cord oxygenation and hemodynamics in patients with acute spinal cord injury (SCI). As a safety assessment measure, we aimed to study the effect of near-infrared (NIR) light emission and contact compression of the NIRS sensor on spinal cord tissue structure. Our previous in-vitro heat tests indicated no heat generation by the NIRS sensor. This study evaluated whether the NIRS sensor resulted in any potential compression damage to the spinal cord using histological analysis. Methods: Six Yucatan mini-pigs received a T10 SCI. A custom implantable NIRS sensor (version 2) was placed extradurally on the spinal cord and fixed with magnets and cross-connectors. After seven days of continuous data collection at 100Hz, the sensor was removed to allow for histological examination of the spinal cord tissue. Cellular damage was observed in the spinal cord at the NIRS sensor placement site in two animals. The design, shape, and material of the NIRS sensor were significantly revised to reduce the sensor footprint, minimize the compression on the cord, increase the sensor flexibility, and improve its clinical application. An in-vivo pilot experiment was performed on a Yucatan miniature pig with a T10 SCI to evaluate potential compression damage of the spinal cord tissue from placement and direct contact of the refined NIRS sensor (version 5). A fibrin sealant, TISSEEL, was utilized to fix the version 5 NIRS sensor on the spinal cord. Result: There were no signs of cellular damage, indentation, and significant flattening on the dorsal surface of the spinal cord where the version 5 NIRS sensor was placed for up to 4.5 hours. Conclusion: The refined NIRS sensor did not cause any compression damage to the porcine spinal cord after implantation for 4.5 hours. Implanting this sensor on the spinal cord of SCI patients requires further in-vivo examinations to ensure the sensor is safe to use for up to 14 days.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables III, 2022

The purpose of this study was to investigate the accuracy of infrared thermography for measuring ... more The purpose of this study was to investigate the accuracy of infrared thermography for measuring body temperature. We compared a commercially available infrared thermal imaging camera (FLIR One) with a medical-grade oral thermometer (Welch-Allyn) as a gold standard. Measurements using the thermal imaging camera were taken from both a short distance (10cm) and long distance (50cm) from the subject. Thirty young healthy adults participated in a study that manipulated body temperature. After establishing a baseline, participants lowered their body temperature by placing their feet in a cold-water bath for 30 minutes while consuming cold water. Feet were then removed and covered with a blanket for 30 minutes as body temperature returned to baseline. During the course of the 70-minute experiment, body temperature was recorded at a 10-minute interval. The thermal imaging camera demonstrated a significant temperature difference from the gold standard from both close range (mean error: +0.433°C) and long range (mean error: +0.522°C). Despite demonstrating potential as a fast and non-invasive method for temperature screening, our results indicate that infrared thermography does not provide an accurate measurement of body temperature. As a result, infrared thermography is not recommended for use as a fever screening device.

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables III

Introduction: We previously developed an implantable near-infrared spectroscopy (NIRS) sensor to ... more Introduction: We previously developed an implantable near-infrared spectroscopy (NIRS) sensor to provide real-time monitoring of spinal cord oxygenation and hemodynamics in a porcine model of acute SCI. Here, we present a method to fix an improved design of the sensor to the spinal cord for up to 14-days post-injury which will be important for its clinical application. Methods: Two Yucatan mini-pigs received a T2 contusion-compression injury. A multi-wavelength NIRS system with a custom-made miniaturized sensor was laid over the dura. The NIRS sensor consisted of a five wavelength LED and photodetector from the previous design. The placement of the LED and photodetector was reconfigured to create a sensor with a slimmer shape. The sensor was mounted on a flexible printed circuit board (PCB) and enclosed by an implantable soft silicone with thin flaps on its side. This allowed the sensor to sit flush on the dura and secured with a fibrin sealant material (TISSEEL), eliminating the need for additional spinal fixation devices. The surgical incision was sutured closed, and the sensor was fixed on the spinal cord while the animal recovered for 14-days post-injury. A fluoroscopy was performed on the surgery day, 7- and 14-days post-injury to assess the positioning of the sensor. Results/Conclusion: The implantable NIRS sensor appeared to remain fixed on the spinal cord after 14-days post-injury upon analysis of fluoroscopy images and examining the re-exposed surgical wound. Securing the NIRS sensor to the spinal cord with a fibrin sealant may provide a method for fixation for up to 14-days post-injury.

Optical Diagnostics and Sensing XXII: Toward Point-of-Care Diagnostics

The Neuroscience Journal of Shefaye Khatam, 2018

Long term video electro-encephalographic (EEG) monitoring (LTM) is defined as the continuous and ... more Long term video electro-encephalographic (EEG) monitoring (LTM) is defined as the continuous and synchronized recording of EEG and multimedia to analyze brain abnormalities. A conventional LTM sys tem continuously records EEG in the frequency range of 0.5-70Hz. The data synchronization, the high-volume data management, the sys tem reliability as well as noise reduction remain significant challenges in an LTM machine. Moreover, online multiuser access to the data during the recording as well as online EEG control remains another essential point. Beyond conventional LTM sys tems, recent s tudies indicate the exis tence of a potentially clinically-relelvant near-DC field potential (f<0.1Hz) among the EEG data. This DC field potential, although sometimes present in healthy subjects, also appears to be associated with a variety of brain abnormalities such as migraines with auras and some types of epileptic activity. Therefore, the EEG frequency range mus t be extended to include lower...

OBJECTIVE Monitoring of the ultra-low frequency potentials, particularly cortical spreading depre... more OBJECTIVE Monitoring of the ultra-low frequency potentials, particularly cortical spreading depression (CSD), is excluded in epilepsy monitoring due to technical barriers imposed by the scalp ultra-low frequency electroencephalogram (EEG). As a result, clinical studies of CSD have been limited to invasive EEG. Therefore, the occurrence of CSD and its interaction with epileptiform field potentials (EFP) require investigation in epilepsy monitoring. METHODS Using a novel AC/DC-EEG approach, the occurrence of DC potentials in patients with intractable epilepsy presenting different symptoms of aura was investigated during long-term video-EEG monitoring. RESULTS Various forms of slow potentials, including simultaneous negative direct current (DC) potentials and prolonged EFP, propagated negative DC potentials, and non-propagated single negative DC potentials were recorded from the scalp of the epileptic patients. The propagated and single negative DC potentials preceded the prolonged EFP...

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables II

A newborn infant has an extraordinarily vulnerable and immature central nervous system, which is ... more A newborn infant has an extraordinarily vulnerable and immature central nervous system, which is undergoing rapid structural and functional development. As these infants are pre-verbal and their neurological systems are immature, assessing accurately and treating effectively procedure-related pain is a significant challenge. The nociceptive signals caused by the pain are accompanied by changes in regional blood oxygenation and neuronal activity in the infant’s brain. In this study, we developed a dual-mode Near-Infrared Spectroscopy (NIRS) and electroencephalography (EEG) monitor that can measure regional brain oxygenation and neuronal activity concurrently (safe and non-invasive). The neuronal activity is measured by an innovative low-noise EEG amplifier in both conventional and ultra-low frequency bandwidths. This multimodal recording allows us to investigate the coupling of neuronal activity and the neurovascular system as never before. NIRS and EEG electrodes are miniaturized and unified in one sensor. This modification facilitates the use of a NIRS/EEG device for recording from neonatal subjects. Ten infants, born between 27-35 weeks gestational age, are being recruited from the NICU at BCWH. They are monitored during a single, routine blood draw required for clinical care. In this experiment, we investigate the change of cerebral hemodynamic across 3 phases of blood collection, baseline, heel lance, recovery. Variation of blood flow accompanied with the slow shift of EEG has been detected during the pain stimulus phase. Additionally, the increase of gamma-band correlated to a rise in blood flow is also observed

According to the WHO, 15,000 children under five years are dying every day from preventable cause... more According to the WHO, 15,000 children under five years are dying every day from preventable causes with 80% of these children being born in low-income countries. Portable optical medical diagnostic devices can help physicians, nurses and untrained health workers to objectively identify children who are at a higher risk of dying. In the last 2 years, we collected the oxygenation values of the brachioradialis muscle, using a commercial Near Infrared Spectroscopy (NIRS) device, in 200 children under 5 years admitted in two hospitals in Uganda. Data revealed that the tissue oxygen saturation decrease during a vascular occlusion predicts children at higher risk better than other vital signs (SpO2, respiration rate, heart rate and temperature). Based on these results, we designed a low cost Continuous Wave Spatially Resolved NIRS device controlled by a smartphone in order to extend our study to a larger population and confirm our observation. The total cost of this device (excluding the s...

2014 21th Iranian Conference on Biomedical Engineering, Nov 1, 2014

We present an automated method for decomposing EMG signals into their components, motor-unit acti... more We present an automated method for decomposing EMG signals into their components, motor-unit action-potential (MUAP) trains based on short time Fourier transform STFT and wavelet transform. Since the number of MUAP classes composing the EMG signal, the number of MUAP’s per class, their firing pattern, and the expected shape of the MUAP waveforms are unknown, the decomposition of real EMG signals into their constituent MUAP’s and their classification into groups of similar shapes is a typical case of an unsupervised learning pattern recognition problem. The method is able to handle single- or multi-channel signals, recorded by concentric needle electrodes during low and moderate levels of muscular contraction. The method uses empirical features in STFT transform, shape and template of MU and CWT in order to decompose the signal to its original MUAP. Also the discrete wavelet transform has been acquired in early steps in order to eliminate the level of low amplitude noise in signal. W...

Neuroscience, 2016

Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pat... more Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pathophysiology of different neurological disorders. Yet, research into SD-related disorders has been hampered by the lack of non-invasive recording techniques of SD. Here we compared the manifestations of SD in continuous non-invasive electroencephalogram (EEG) recordings to invasive electrocorticographic (ECoG) recordings in order to obtain further insights into generator structures and electrogenic mechanisms of surface recording of SD. SD was induced by KCl application and simultaneous SD recordings were performed by scalp EEG as well as ECoG electrodes of somatosensory neocortex of rats using a novel homemade EEG amplifier, AgCl recording electrodes, and high chloride conductive gel. Different methods were used to analyze the data; including the spectrogram, bi-spectrogram, pattern distribution, relative spectrum power, and multivariable Gaussian fit analysis. The negative DC shifts recorded by scalp electrodes exhibited a high homogeneity to those recorded by ECoG electrodes. Furthermore, this novel method of recording and analysis was able to separate SD recorded by scalp electrodes from non-neuronal DC shifts induced by other potential generators, such as the skin, muscles, arteries, dura, etc. These data suggest a novel application for continuous non-invasive monitoring of DC potential changes, such as SD. Non-invasive monitoring of SD would allow early intervention and improve outcome in SDrelated neurological disorders.

Neuroscience, Oct 1, 2016

Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pat... more Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pathophysiology of different neurological disorders. Yet, research into SD-related disorders has been hampered by the lack of non-invasive recording techniques of SD. Here we compared the manifestations of SD in continuous non-invasive electroencephalogram (EEG) recordings to invasive electrocorticographic (ECoG) recordings in order to obtain further insights into generator structures and electrogenic mechanisms of surface recording of SD. SD was induced by KCl application and simultaneous SD recordings were performed by scalp EEG as well as ECoG electrodes of somatosensory neocortex of rats using a novel homemade EEG amplifier, AgCl recording electrodes, and high chloride conductive gel. Different methods were used to analyze the data; including the spectrogram, bi-spectrogram, pattern distribution, relative spectrum power, and multivariable Gaussian fit analysis. The negative DC shifts recorded by scalp electrodes exhibited a high homogeneity to those recorded by ECoG electrodes. Furthermore, this novel method of recording and analysis was able to separate SD recorded by scalp electrodes from non-neuronal DC shifts induced by other potential generators, such as the skin, muscles, arteries, dura, etc. These data suggest a novel application for continuous non-invasive monitoring of DC potential changes, such as SD. Non-invasive monitoring of SD would allow early intervention and improve outcome in SDrelated neurological disorders.