Hadi Borjkhani - Academia.edu (original) (raw)

Papers by Hadi Borjkhani

PLOS ONE, 2020

Recent advances in optical neuroimaging systems as a functional interface enhance our understandi... more Recent advances in optical neuroimaging systems as a functional interface enhance our understanding of neuronal activity in the brain. High density diffuse optical topography (HD-DOT) uses multi-distance overlapped channels to improve the spatial resolution of images comparable to functional magnetic resonance imaging (fMRI). The topology of the source and detector (SD) array directly impacts the quality of the hemodynamic reconstruction in HD-DOT imaging modality. In this work, the effect of different SD configurations on the quality of cerebral hemodynamic recovery is investigated by presenting a simulation setup based on the analytical approach. Given that the SD arrangement determines the elements of the Jacobian matrix, we conclude that the more individual components in this matrix, the better the retrieval quality. The results demonstrate that the multi-distance multi-directional (MDMD) arrangement produces more unique elements in the Jacobian array. Consequently, the inverse problem can accurately retrieve the brain activity of diffuse optical topography data.

2013 20th Iranian Conference on Biomedical Engineering (ICBME), 2013

Currently need for ultra low power wireless transmitters in medical applications are inevitable. ... more Currently need for ultra low power wireless transmitters in medical applications are inevitable. In this paper a new transmitter for body-worn and implantable sensor nodes is presented. Most of the sensor nodes supply their power using energy harvesting instead of a battery, since the power earned by harvesting is limited, so the average and the peak power consumption of the sensor node must be minimized. Transmitter blocks which implemented in sensor nodes are too power consuming. So a new low power Binary Frequency Shift Keying (BFSK) transmitter based on sub-harmonic current mode injection locking, and edge combining technique has been proposed. The proposed transmitter was designed to make a mutual communication between sensor node and base station, so there is no need for complexity at receiver side. In order to reduce the consuming power at transmitter side, BFSK modulation is done at reference frequency to prevent usage of power consuming low phase noise oscillator at carrier frequency. A 34MHz reference clock is used and the frequency of reference clock multiplied by 12 for desired carrier frequency. The phase noise of the carrier at 1MHz frequency offset is-117 dBc/Hz. Total power consumption of the transmitter is about 144µW. The output carrier frequency is 408MHz. BFSK modulation scheme is used at the frequency much lower than the carrier frequency in order to reduce the power consumption.

2014 22nd Iranian Conference on Electrical Engineering (ICEE), 2014

This paper proposes a new current starved ring oscillator based on current mode injection locked ... more This paper proposes a new current starved ring oscillator based on current mode injection locked frequency multiplier (ILFM). This low power oscillator is the main building block of low power transceivers. These transceivers are mainly used in biomedical sensor nodes, where the consuming power is crucial. The operation frequency of the oscillator was chosen to be 500MHz. One 50MHz accurate low phase noise reference signal is used to improve the phase noise of the oscillator. Deliberately, bias current of the oscillator can change and subsequently pulls the frequency of free running oscillator to the harmonics of the reference signal. Total power consumption of the oscillator at 500MHz, is 25μW, the oscillator locks to the 10th harmonic of the reference signal. The order of the multiplication can be increased or reduced by increase and reduction in the bias current of the oscillator. The proposed circuit has been simulated under Advanced Design System simulator using TSMC RF CMOS 0.18um technology.

Basic and Clinical Neuroscience Journal

Introduction: Drugs of abuse, including cocaine, affect different brain regions and lead to patho... more Introduction: Drugs of abuse, including cocaine, affect different brain regions and lead to pathological memories. These abnormal memories may occur due to the changes in synaptic transmissions or variations in synaptic properties of neurons. It has been shown that cocaine inhibits delayed rectifying potassium currents in affected regions of the brain and can have a role in the formation of pathological memories. Purpose: This study investigates how the change in the conductance of delayed rectifying potassium channels can affect the produced action potentials using a computational model. Methods: We present a computational model with different channels and receptors, including sodium, potassium, calcium, NMDARs, and AMPARs, which can produce burst-type action potentials. In the simulations, by changing the delayed rectifying potassium conductance bifurcation diagram is calculated. Conclusion: Results show that for a specific range of potassium conductance, a chaotic regime emerges ...

International Journal of Circuit Theory and Applications

Basic and Clinical Neuroscience Journal, 2021

Introduction: Functional Near-Infrared Spectroscopy (fNIRS) is an imaging method in which light s... more Introduction: Functional Near-Infrared Spectroscopy (fNIRS) is an imaging method in which light source and detector are installed on the head; consequently, re-emission of light from human skin contains information about cerebral hemodynamic alteration. The spatial probability distribution profile of photons penetrating tissue at a source spot, scattering into the tissue, and being released at an appropriate detector position, represents the spatial sensitivity. Method: Modeling light propagation in a human head is essential for quantitative near-infrared spectroscopy and optical imaging. The specific form of the distribution of light is obtained using the theory of perturbation. Analytical solution of the perturbative Diffusion Equation (DE) and Finite Element Method (FEM) in a Slab media (similar to the human head) makes it possible to study light propagation due to absorption and scattering of brain tissue. Results: The simulation result indicates that sensitivity is slowly decre...

PLOS ONE, 2020

Recent advances in optical neuroimaging systems as a functional interface enhance our understandi... more Recent advances in optical neuroimaging systems as a functional interface enhance our understanding of neuronal activity in the brain. High density diffuse optical topography (HD-DOT) uses multi-distance overlapped channels to improve the spatial resolution of images comparable to functional magnetic resonance imaging (fMRI). The topology of the source and detector (SD) array directly impacts the quality of the hemodynamic reconstruction in HD-DOT imaging modality. In this work, the effect of different SD configurations on the quality of cerebral hemodynamic recovery is investigated by presenting a simulation setup based on the analytical approach. Given that the SD arrangement determines the elements of the Jacobian matrix, we conclude that the more individual components in this matrix, the better the retrieval quality. The results demonstrate that the multi-distance multi-directional (MDMD) arrangement produces more unique elements in the Jacobian array. Consequently, the inverse problem can accurately retrieve the brain activity of diffuse optical topography data.

2013 20th Iranian Conference on Biomedical Engineering (ICBME), 2013

Currently need for ultra low power wireless transmitters in medical applications are inevitable. ... more Currently need for ultra low power wireless transmitters in medical applications are inevitable. In this paper a new transmitter for body-worn and implantable sensor nodes is presented. Most of the sensor nodes supply their power using energy harvesting instead of a battery, since the power earned by harvesting is limited, so the average and the peak power consumption of the sensor node must be minimized. Transmitter blocks which implemented in sensor nodes are too power consuming. So a new low power Binary Frequency Shift Keying (BFSK) transmitter based on sub-harmonic current mode injection locking, and edge combining technique has been proposed. The proposed transmitter was designed to make a mutual communication between sensor node and base station, so there is no need for complexity at receiver side. In order to reduce the consuming power at transmitter side, BFSK modulation is done at reference frequency to prevent usage of power consuming low phase noise oscillator at carrier frequency. A 34MHz reference clock is used and the frequency of reference clock multiplied by 12 for desired carrier frequency. The phase noise of the carrier at 1MHz frequency offset is-117 dBc/Hz. Total power consumption of the transmitter is about 144µW. The output carrier frequency is 408MHz. BFSK modulation scheme is used at the frequency much lower than the carrier frequency in order to reduce the power consumption.

2014 22nd Iranian Conference on Electrical Engineering (ICEE), 2014

This paper proposes a new current starved ring oscillator based on current mode injection locked ... more This paper proposes a new current starved ring oscillator based on current mode injection locked frequency multiplier (ILFM). This low power oscillator is the main building block of low power transceivers. These transceivers are mainly used in biomedical sensor nodes, where the consuming power is crucial. The operation frequency of the oscillator was chosen to be 500MHz. One 50MHz accurate low phase noise reference signal is used to improve the phase noise of the oscillator. Deliberately, bias current of the oscillator can change and subsequently pulls the frequency of free running oscillator to the harmonics of the reference signal. Total power consumption of the oscillator at 500MHz, is 25μW, the oscillator locks to the 10th harmonic of the reference signal. The order of the multiplication can be increased or reduced by increase and reduction in the bias current of the oscillator. The proposed circuit has been simulated under Advanced Design System simulator using TSMC RF CMOS 0.18um technology.

Basic and Clinical Neuroscience Journal

Introduction: Drugs of abuse, including cocaine, affect different brain regions and lead to patho... more Introduction: Drugs of abuse, including cocaine, affect different brain regions and lead to pathological memories. These abnormal memories may occur due to the changes in synaptic transmissions or variations in synaptic properties of neurons. It has been shown that cocaine inhibits delayed rectifying potassium currents in affected regions of the brain and can have a role in the formation of pathological memories. Purpose: This study investigates how the change in the conductance of delayed rectifying potassium channels can affect the produced action potentials using a computational model. Methods: We present a computational model with different channels and receptors, including sodium, potassium, calcium, NMDARs, and AMPARs, which can produce burst-type action potentials. In the simulations, by changing the delayed rectifying potassium conductance bifurcation diagram is calculated. Conclusion: Results show that for a specific range of potassium conductance, a chaotic regime emerges ...

International Journal of Circuit Theory and Applications

Basic and Clinical Neuroscience Journal, 2021

Introduction: Functional Near-Infrared Spectroscopy (fNIRS) is an imaging method in which light s... more Introduction: Functional Near-Infrared Spectroscopy (fNIRS) is an imaging method in which light source and detector are installed on the head; consequently, re-emission of light from human skin contains information about cerebral hemodynamic alteration. The spatial probability distribution profile of photons penetrating tissue at a source spot, scattering into the tissue, and being released at an appropriate detector position, represents the spatial sensitivity. Method: Modeling light propagation in a human head is essential for quantitative near-infrared spectroscopy and optical imaging. The specific form of the distribution of light is obtained using the theory of perturbation. Analytical solution of the perturbative Diffusion Equation (DE) and Finite Element Method (FEM) in a Slab media (similar to the human head) makes it possible to study light propagation due to absorption and scattering of brain tissue. Results: The simulation result indicates that sensitivity is slowly decre...