Fadi Jaber

Action potential recording from dielectrophoretically positioned neurons inside micro-wells of a planar microelectrode array

To organise in vitro neural networks at the cellular level and study their electrical patterns, we have fabricated 4 x 4 planar microelectrode arrays using conventional photolithography. The electrode sites of these arrays are located inside micro-wells, for confining the neurons, which are connected with neighbouring wells via micro-trenches capable of guiding the outgrowth of neurites. In order to load a single neuron inside each micro-well, a simple system has been developed that utilises the phenomenon of dielectrophoresis. It operates by moving neurons towards each electrode site of an array using a dielectrophoretic force, checking for the presence of a neuron inside each micro-well using image processing, and stopping the dielectrophoretic force when detecting a neuron inside a micro-well in order to prevent more cells from being trapped. This system provides a fast, effective and inexpensive way to assemble neural grids consisting of contacts between electrodes and single neurons, as the use of micromanipulator guided micropipettes can be avoided. Spontaneous and evoked action potentials from trapped neurons were successfully recorded using a 16-channel acquisition/stimulation unit.

Novel Approach to Non-Invasive Blood Glucose Monitoring Based on Transmittance and Refraction of Visible Laser Light

Current blood glucose monitoring (BGM) techniques are invasive as they require a finger prick blood sample, a repetitively painful process that creates the risk of infection. BGM is essential to avoid complications arising due to abnormal blood glucose levels in diabetic patients. Laser light-based sensors have demonstrated a superior potential for BGM. Existing near-infrared (NIR)-based BGM techniques have shortcomings, such as the absorption of light in human tissue, higher signal-to-noise ratio, and lower accuracy, and these disadvantages have prevented NIR techniques from being employed for commercial BGM applications. A simple, compact, and cost-effective non-invasive device using visible red laser light of wavelength 650 nm for BGM (RL-BGM) is implemented in this paper. The RL-BGM monitoring device has three major technical advantages over NIR. Unlike NIR, red laser light has ~30 times better transmittance through human tissue. Furthermore, when compared with NIR, the refractive index of laser light is more sensitive to the variations in glucose level concentration resulting in faster response times ~7–10 s. Red laser light also demonstrates both higher linearity and accuracy for BGM. The designed RL-BGM device has been tested for both in vitro and in vivo cases and several experimental results have been generated to ensure the accuracy and precision of the proposed BGM sensor.

A Wireless Oxygen Saturation and Heart Rate Monitoring and Alarming System Based on the Qatar Early Warning Scoring System

Monitoring vital signs and alarming healthcare emergency response units whenever measurements are outside the normal range could be life-saving for high-risk patients who are living alone or sleeping. This paper presents a system that wirelessly obtains the oxygen saturation and heart rate from patients using a pulse oximeter. An SMS alarm with the measurements is then sent to hospitals to contact the patient or dispatch an ambulance in case he/she does not respond. The SMS also contains the patients GPS coordinates. The decision whether an alarming SMS should be sent is based on the Qatar Early Warning Scoring (QEWS) system. In this work, a base station unit to receive and analyze data coming from the sensor was developed and tested.

An EMG signal processing system for control of an ankle-foot orthosis

This paper presents an electromyographic (EMG)-based digital processing system for estimating foot direction of motion and force exerted from muscles of the human lower leg. This information can be used in the control frameworks of ankle-foot orthoses (AFOs). In essence, it is usually necessary to estimate the ankles muscles voluntary contraction (VC) and users intention of motion in order to control an AFO in a reliable and effective way. Consequently, a data processing system is developed that can designate these parameters from EMG signals. The voluntary contraction is calculated based on the root mean square (RMS) of EMG signals, and the direction of motion is estimated by using a feature-based classifier. The experiments are performed on five healthy, sitting subjects and the methodology consists of selecting discriminative features and using basic classifiers. The results of this work show that the direction of motion can be estimated in real-time with high accuracy.

Development of LPV models and switching LPV-H ∞ controller for a hydraulic system

This paper describes the development of linear parameter varying (LPV) models and an LPV-H∞ controller for one degree of freedom (DoF) electro-hydraulic systems. A virtual set-up consists of a hydraulic actuator driven by a servovalve and supplied from a constant-pressure power unit. The LPV models are derived based on two techniques: black-box modeling and the analytical description of the system (white box modeling). Both methods are compared to each other and the derived models have been used for the design of the switching LPV-controller. Simulation results indicate predominance of adapting LPV framework to a hydraulic system control over conventional approaches.

Theoretical investigation on the effect of individual stage-gain selection on the 3-dB bandwidth of three-op-amp difference amplifiers

The differential gain of a three-op-amp difference amplifier is determined by the product of the gain values of its two stages. Usually, the total desired differential gain is assigned to the first stage while the gain of the second stage is set to unity in order to achieve higher common mode rejection ratio (CMRR) values. On the other hand, the effect of this choice on the frequency response of the amplifier is not fully understood. For this purpose, this paper presents a theoretical study on the influence of gain choice for the first and second stages of the amplifier on its 3-dB bandwidth. To achieve this, the closed-loop transfer function of the amplifier is derived while considering the effect of the finite open-loop gain and bandwidth of the op-amps used to implement this type of amplifier. The equations presented here demonstrate that the 3-dB bandwidth is increased considerably when the gain of the first stage is reduced and that of the second stage is raised while keeping the value of the total differential gain constant. Although this happens at the expense of CMRR, designers of this type of amplifier should consider the tradeoff between the two.

A phantom for cadaverless evaluation of targeting systems for distal locking of intramedullary nails

One of the most challenging parts of intramedullary nailing is finding the location of the distal holes of the intramedullary nail following its insertion along the medullary canal. The preferred method for locating the distal holes involves the use of x-ray imaging. In order to reduce the exposure of the medical personnel and patient to ionizing radiation several alternative methods are being investigated and their feasibility and accuracy are being assessed by performing surgery on cadavers. Due to several issues associated with cadavers, this paper introduces a phantom as an alternative tool for the evaluation of such techniques. The features associated with this phantom should allow researchers to assess the performance of their distal locking systems at a reduced cost and without the need for surgical skills.