Mohammed M Shobaki

High quality acquisition of surface electromyography – conditioning circuit design

The acquisition of Surface Electromyography (SEMG) signals is used for many applications including the diagnosis of neuromuscular diseases, and prosthesis control. The diagnostic quality of the SEMG signal is highly dependent on the conditioning circuit of the SEMG acquisition system. This paper presents the design of an SEMG conditioning circuit that can guarantee to collect high quality signal with high SNR such that it is immune to environmental noise. The conditioning circuit consists of four stages; consisting of an instrumentation amplifier that is used with a gain of around 250; 4th order band pass filter in the 20–500Hz frequency range as the two initial stages. The third stage is an amplifier with adjustable gain using a variable resistance; the gain could be changed from 1000 to 50000. In the final stage the signal is translated to meet the input requirements of data acquisition device or the ADC. Acquisition of accurate signals allows it to be analyzed for extracting the required characteristic features for medical and clinical applications. According to the experimental results, the value of SNR for collected signal is 52.4 dB which is higher than the commercial system, the power spectrum density (PSD) graph is also presented and it shows that the filter has eliminated the noise below 20 Hz.

Experimental evaluation of agricultural biomass flow sensing behaviour using capacitive technique

To enhance industry control quality level as well as uphold enterprise economic benefit precise sensing and measurement of biomass flow is a major concern among researchers worldwide. Keeping in mind the shortcomings of existing sensing technologies this paper has developed a capacitive sensing method by making use of aop amp based bridge circuit along with particularly designed sensing electrodes. The objective of this work is fulfilled via experimental validation through a prototype hardware implementation of a flow sensing set up. The experimental results have specified the measurement system which is able to sense flow variation as a change of dielectric permittivity of different biomass materials under room condition. Moreover, the obtained results have revealed distinctive features clearly signifying the shapes and physical characteristics of electrodes, locations of the mounted electrodes on test pipe wall, dielectric permittivity and characteristics of test biomass materials.

A Comparative Study of Small Voltage Rectification Circuits for Implanted Devices

Biomedical implants have acquired an invulnerable and significant importance over the recent years due to their low voltage requirements and trifling dimensions. Biomedical implants are being widely employed for the continuous monitoring of intended parameters as well as stimulation of target organs in patients body. Being low power devices, the continuous powering without using battery dependent sources necessitates the alternative sources such as energy harvesting from the surroundings. Harvested output needs to be processed before using it for powering purposes, particularly in harsh and challenging premises. Even after processing, it needs to be made robust against the contiguous hazards so that maximum power is transferred to the load. A rectifier is employed to make this harvested energy usable. This paper compares the rectifier circuits, comparing their simulation output in terms of regulation, stability and power transferred. The rectification of small voltages is usually confronted by the threshold voltage drops that affect the output causing an effective drop in the power transfer efficiency and other parameters related. The solution to this problem has been suggested comparing the previous approaches with some modifications. Obtained results have been plotted in terms of ripple factor comparing them with the analytical calculations in order to show the role of capacitance in the reduction of ripple factor.

Posture Characterization Based on Time and Frequency Domain Parameters for Erector Spine SEMG Signal

This work is based on obtaining surface EMG signals from lower back muscles using a data logger by Pico Log technology. The electrodes used are Ag/AgCl and applied after a clean surface washing by alcohol of erector spine muscle for a subject under two posture conditions. The conditioning circuit used in this paper is selectively choosing the 20-500Hz dominant frequency range and 0.4 to 2.4 Volts in amplitude. The data on signals are transported onto a PC into Excel file for processing its FFT representative of the target posture condition. The bow condition shows four times larger in magnitude of FFT compared to that of standing condition over a similar frequency range of 50-220Hz. The utility of the conditioning circuit is justified by reducing the power frequency noise to negligible level. The utility of this research work has potential in clinical diagnostic applications.

Acquisition of a Very Low Voltage and a Low Frequency Biomedical Signal - Frequency Selective Filter Design

In this paper we present a review on the frequency content and voltage level in biomedical signals beside showing how extraction of chosen features and parameters from these signals, are important for many medical diagnostic applications. A 4th order band-pass filter using high and low-pass Sallen Key active filters are proposed, and the values of passive component for different biomedical filters have been provided. The circuits are simulated and the frequency response is shown. The power spectrum density (PSD) of an EMG signals is presented where it becomes clear that the PSD graph can provide the value of the bandwidth for the signal of interest. The response of the filter is validated and the utility of the conditioning circuit is testified.

A qualitative review for wireless health monitoring system

A proliferating interest has been being observed over the past years in accurate wireless system development in order to monitor incessant human activities in health care centres. Furthermore because of the swelling number of elderly population and the inadequate number of competent staffs for nursing homes there is a big market petition for health care monitoring system. In order to detect human researchers developed different methods namely which include Field Identification technique, Visual Sensor Network, radar detection, e-mobile techniques and so on. An all-encompassing overview of the non-wired human detection application advancement is presented in this paper. Inductive links are used for human detection application while wiring an electronic system has become impractical in recent times. Keeping in mind the shortcomings, an Inductive Intelligent Sensor (IIS) has been proposed as a novel human monitoring system for future implementation. The proposed sensor works towards exploring the signature signals of human body movement and size. This proposed sensor is fundamentally based on inductive loop that senses the presence and a passing human resulting an inductive change.

Performance characterization of inductive coupling system

The use of biomedical implants has been on the rise over the recent past years and this use is expected to increase exponentially over the comings years. Such devices are becoming the most feasible interface to monitor the betrothed parameters. Biomedical implants usually require a low input voltage which is provided making use of inductive coupling. Inductive coupling not only solves the powering issue but also helps to collect the data through non-invasive means. Power transfer efficiency of an inductive link system depends upon factors like mutual coupling, separation between the coils and most importantly the shape of the input voltage. The power transferred or signal received as a result of coil separation under optimum size conditions are reported in contemporary works. This paper comes is testing the effect of different shaped input voltages on the performance of inductive coupling system in terms of power transfer efficiency. Circuits have been tested for three different types of input waveforms of sine, square and ramp. Comparison of plots shows that the shape of input plays a major role on the entire performance of inductive coupling system.

Optimization of wireless power transmission for two port and three port inductive link

Recent developments have shown that the use of buried electronic devices or body implants has been becoming prevalent. Such low power devices are being powered up through non-contact means utilizing inductive coupling from external powering source. Inductive coupling not only solves the issue of energy availability but helps collecting the sensed data that can be archived or used for subsequent monitoring purposes. This paper analyses the performance of two-port and three-port inductive links in terms of power sent, power received and power transfer efficiency. All the above mentioned parameters have been plotted using analytical approach and obtaining simulation where required. The effect of mutual coupling has been studied in detail for both systems and demonstrated by plotting the power transfer efficiency for different values of the coefficient of coupling (k) using MATLAB. Results show that power transfer efficiency depends highly upon the value of k.

Inductive Loops for Sensing Position as Signature Signals

In this paper, an inductive sensing technique made of a special shaped inductive loop is proposed. The inductive loop has an inner turn fitted within an outer turn, making a total inductance value 100μH. This loop is made to be shown with balanced response using three capacitance values of 0.068μF each when a sinusoidal voltage source of 5V peak-to-peak is applied. The variation of the relative permeability of the inductance of the inductive loop (AL) results in a variation of the overall inductance value (L+AL), that causes the output signal to change in term of shape and amplitude for variation of total inductance sweep over a given period of time. As a result of change in inductance value (lμH) there is a correspondence increase of 300mV. Theoretical derivations have showed in close agreement with the simulation plots obtained using Multisim software.

Transforming human gait for signature signals characterization

An integrated wireless inductive sensor is reported based on a system for monitoring human movement and body size. The proposed system senses the presence of human beings using electromagnetic field by making use of basic inductive coupling approach, hence analysing the performance of human monitoring. The amalgamation of the integrated system proposed will help in providing better services to the elderly people resided in healthcare centres. The developed sensing system is of low cost, flexible, robust, and easily implantable and capable of inductive sensing through marking signature waveforms as a result of human movements.