Selectivity and Longevity of Peripheral-Nerve and Machine Interfaces: A Review

Ghafoor, Usman,Kim, Sohee,Hong, Keum-Shik Frontiers Media S.A. 2017 Frontiers in neurorobotics Vol.11 No.-

<P>For those individuals with upper-extremity amputation, a daily normal living activity is no longer possible or it requires additional effort and time. With the aim of restoring their sensory and motor functions, theoretical and technological investigations have been carried out in the field of neuroprosthetic systems. For transmission of sensory feedback, several interfacing modalities including indirect (non-invasive), direct-to-peripheral-nerve (invasive), and cortical stimulation have been applied. Peripheral nerve interfaces demonstrate an edge over the cortical interfaces due to the sensitivity in attaining cortical brain signals. The peripheral nerve interfaces are highly dependent on interface designs and are required to be biocompatible with the nerves to achieve prolonged stability and longevity. Another criterion is the selection of nerves that allows minimal invasiveness and damages as well as high selectivity for a large number of nerve fascicles. In this paper, we review the nerve-machine interface modalities noted above with more focus on peripheral nerve interfaces, which are responsible for provision of sensory feedback. The invasive interfaces for recording and stimulation of electro-neurographic signals include intra-fascicular, regenerative-type interfaces that provide multiple contact channels to a group of axons inside the nerve and the extra-neural-cuff-type interfaces that enable interaction with many axons around the periphery of the nerve. Section Current Prosthetic Technology summarizes the advancements made to date in the field of neuroprosthetics toward the achievement of a bidirectional nerve-machine interface with more focus on sensory feedback. In the Discussion section, the authors propose a hybrid interface technique for achieving better selectivity and long-term stability using the available nerve interfacing techniques.</P>

Enhancement in classification accuracy of motor imagery signals with visual aid: An fNIRS-BCI Study

Usman Ghafoor,Amad Zafar,M. Atif Yaqub,Keum-Shik Hong 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10

One of the most promising brain activity utilized in brain-computer interface (BCI) is motor imagery (MI). Due to weak hemodynamic response (HR) signal, the achieved classification accuracies using MI are not sufficiently high. In this study, the enhancement in HR was investigated during motor imagery tasks of ball squeezing with the right hand. Brain signals in the form of concentration changes in oxy-hemoglobin (ΔHbO) and deoxy-hemoglobin (ΔHbR) from the left sensorimotor cortex were obtained using functional near-infrared spectroscopy (fNIRS). The experiment was separated in two sessions: In the first session the MI task was performed without a visual aid, and in the second session of the same task, the visual aid was provided: A video was played on a screen that showed a person continuously squeezing the ball, which can help in enhancing the imagination, thus improvement in HR. Later the features of averaged ΔHbO were used for classification. The active channels were selected on the basis of t-values and trials of those channels were mean to obtain averaged ΔHbO. Consistent with literature, imagery task with visual aid, showed increased activation in ΔHbO. Moreover, linear discriminant analysis was used to classify signals by taking the mean and peak of the averaged ΔHbO resulting in average classification accuracies of approximately 66% and 77% for MI task, with and without visual aid, respectively. These results are convincing that showed improvement in MI ability which will be useful for fNIRS-based BCI applications.

Cortical activation during voluntary and passive movement of human index finger

Usman Ghafoor,Amad Zafar,Keum-Shik Hong 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10

Passive movement, motor imagery, and observation of movement have been able to activate the somatosensory and motor cortex of brain without voluntary movement. In this paper, we have investigated cortical activation in brain using a finger movement passive mode together with voluntary movement and analysis is based on within-subject design protocol. Five subjects have participated in movement of finger tasks meanwhile their brain activity is monitored using functional near-infrared spectroscopy (fNIRS). The two gamma functions are used to model the conventional hemodynamic response function (cHRF) to determine the active locations. The t-maps (brain maps) are generated for the comparison of oxy-hemoglobin (HbO) responses of both voluntary and passive movement of index finger tasks. The results have demonstrated that both movement modes activated sensorimotor areas. The neural activation pattern in voluntary execution of finger is somewhat similar to passive movement. The results of this study will help in checking whether passive movements can be able to induce suitable amount of somatosensory stimulation. Our results inveterate that the voluntary and passive movement task are strongly coupled, supporting the importance of passive tasks as a diagnostic tool in the clinical setting.

Determination of the parameters in the designed hemodynamic response function using Nelder-Mead algorithm

Amad Zafar,Usman Ghafoor,M. Atif Yaqub,Keum-Shik Hong 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10

In this paper, we have investigated the use of the Nelder-Mead algorithm in determining the parameters of a designed hemodynamic response function (dHRF) instead of using fixed parameters for functional near-infrared spectroscopy (fNIRS). The hemodynamic response (HR) is supposed to be a linear combination of the baseline, the dHRF, and physiological noises (Mayer, cardiac, and respiration). The linear combination of three gamma functions is used to model the dHRF including the initial dip, the conventional HR, and the undershoot afterward. In this formulation, fifteen parameters (9 for dHRF and 6 for physiological noises) are unknown. An objective function is designed and solved using the iterative optimization Nelder-Mead algorithm to determine the unknown parameters of dHRF and physiological noises. The performance of the algorithm is tested using simulated and experimental datasets. The fNIRS experimental data were acquired from five healthy subjects during right-hand thumb finger flexion/extension tasks from the left motor cortex. The results demonstrate that inter-subject differences existed in the dHRF parameters. Therefore, it will be worthwhile to use subject-dependent dHRF parameters for a better estimation of the cortical activation using fNIRS.

Development of a High Density Neuroimaging System Using Functional Near-Infrared Spectroscopy

M. Atif Yaqub,Amad Zafar,Usman Ghafoor,Keum-Shik Hong 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10

The progress in the field of neuroscience is critical in our rapidly aging society as the fatality rate due to brain degenerative diseases is rising. Recently, functional near-infrared spectroscopy (fNIRS) has established its application in measuring the blood chromophores’ concentration changes during an activity. In this developmental study, we have introduced our lab-developed fNIRS system that is able to compute the concentration changes in oxy-hemoglobin and deoxy-hemoglobin from the optical NIR light signals. We have employed 128 dual wavelength light emitting diodes (LEDs) of 735 nm and 850 nm in the designed system. LED driving circuit was designed by using serial peripheral interface based output expansion chips. A single photodiode (PD) was used for measuring the NIR light intensity received after passing through the brain tissue and getting absorbed and scattered in the process. Our system uses a battery for supplying power to the system. A wireless communication module was interfaced with the system for transferring the fNIRS data to our developed software running on a host computer. The software is capable of displaying the real-time data and record it for future processing. To test the functionality of the system, a phantom brain model was used. The LED and PD were attached to the phantom and multiple combinations of LEDs were tested to provide robust data. Our lab-developed fNIRS system showed the acquired intensity values for both wavelengths which corresponds to hemoglobin changes in 128 channels.

A Mobile Manipulator For Logistic Applications

Arshman Amer Awan,Osama Aftab Usman,Muhammad Zubair Khan,Usman Ghafoor,M. Raheel Bhutta 제어로봇시스템학회 2023 제어로봇시스템학회 국제학술대회 논문집 Vol.2023 No.10

Polyaniline-engineered zinc sulphide nanocomposite as a highly efficient electrocatalyst for the oxygen evolution process

Alenad Asma M.,Fatima Sofia,Khalid Usman,Bano Nigarish,Abid Abdul Ghafoor,Manzoor Sumaira,Farid Hafiz Muhammad Tahir,Messali Mouslim,Alzahrani Huda A.,Taha Taha Abdel Mohaymen 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.5

Hydrogen is the ideal future fuel, since it is clean, saves energy, and is abundant in nature. Though there are several methods for producing hydrogen, only a few of them are environmentally friendly. To employ water electrolysis to make hydrogen and solve the energy shortage problem, highly active electrocatalysts must be created. Zinc sulphide/polyaniline (ZnS/PANI) nanocomposite was successfully produced using a straightforward two-step coprecipitation and polymerization procedure. Different analyses were used to characterize the fabricated materials. The findings show that the ZnS/PANI nanocomposite's morphology has a consistent porous shape, and the electrical structure of the active sites determines how well catalysts can make contact with the intermediates. Multiple attempts have been made to create the most affordable, functional electrocatalyst for oxygen evolution reactions (OER). However, clean energy production from such materials is sluggish. In comparison to pure PANI nanofibers (143.14 m2 g−1 and 0.4827 nm) and ZnS nanostructures (249.85 m2 g−1 and 0.4224 nm), the composite ZnS/PANI displays a greater Brunauer–Emmett–Teller (BET) surface area around 372.65 m2 g−1 along with nanoporous size of 0.393 nm due to the interaction, which provides distinctive features in contrast to ZnS and PANI. Synergistically, composite ZnS/PANI indicates lower overpotentials of 132 mV for oxygen evolution performance at 10 mA cm−2. An improved OER activity is observed by composite ZnS/PANIs as high current density, lower overpotential and reduced Tafel value of 53 mV dec−1. This catalyst also exhibited a significant double-layer capacitance and a large electrochemically active surface area. ZnS/PANI is a magnificent electrocatalyst for oxygen evolution.