Yehya H. Ghallab

A novel current-mode instrumentation amplifier based on operational floating current conveyor

This paper presents a novel current-mode instrumentation amplifier (CMIA) that utilizes an operational floating current conveyor (OFCC) as a basic building block. The OFCC, as a current-mode device, shows flexible properties with respect to other current- or voltage-mode circuits. The advantages of the proposed CMIA are threefold. First, it offers a higher differential gain and a bandwidth that is independent of gain, unlike a traditional voltage-mode instrumentation amplifier. Second, it maintains a high common-mode rejection ratio (CMRR) without requiring matched resistors, and finally, the proposed CMIA circuit offers a significant improvement in accuracy compared to other current-mode instrumentation amplifiers based on the current conveyor. The proposed CMIA has been analyzed, simulated, and experimentally tested. The experimental results verify that the proposed CMIA outperforms existing CMIAs in terms of the number of basic building blocks used, differential gain, and CMRR.

Sensing methods for dielectrophoresis phenomenon: from bulky instruments to lab-on-a-chip

Recently, the sensing methods for dielectrophoresis (DEP) have been changed from bulky instruments to lab-on-a-chip. Lab-on-a-chip based the dielectrophoresis phenomenon holds the promise to give biology the advantage of miniaturization for carrying out complex experiments. However, until now, there is an unmet need for lab-on-a-chip to effectively deal with the biological systems at the cell level.

A new topology for a current-mode wheatstone bridge

This paper presents a new topology for a current-mode Wheatstone bridge (CMWB) that uses an operational floating current conveyor (OFCC) as a basic building block. The proposed CMWB has been analyzed, simulated, implemented, and experimentally tested. The experimental results verify that the proposed CMWB outperforms existing CMWBs in terms of accuracy. A new CMWB linearization technique based on OFCC has been proposed, used, analyzed, and tested. The advantages of the proposed CMWB are fourfold. Firstly, it reduces the number of sensing passive elements; i.e., we can use two resistors instead of four and get the same performance as the traditional voltage-mode implementation. Secondly, we can apply the superposition principle without adding signal conditioning circuitry; therefore, the addition of sensor effects is possible. Thirdly, it has a higher common-mode cancellation. Finally, the proposed CMWB topology offers a significant improvement in accuracy compared to other CMWBs

THE OPERATIONAL FLOATING CURRENT CONVEYOR AND ITS APPLICATIONS

A five-port general-purpose analog building block, termed as an Operational Floating Current Conveyor (OFCC), is described. The OFCC combines the features of current feedback operational amplifier, second-generation current conveyor and operational floating conveyor. An implementation scheme of the OFCC is described and its terminal operational characteristics are used to yield a working device. The OFCC is then used as a single block to realize the current conveyors (CCII+ and CCII-) as well as the four basic amplifiers (i.e., voltage, current, transconductance, and transresistance amplifiers). The applications of the OFCC are presented and discussed. In the field of the analog filter synthesis, we proposed a new active universal second order filter using OFCC. It has three inputs and one output employing two OFCC, two capacitors and three resistors and can realize lowpass, bandpass, highpass, notch, and all pass filters from the same configuration. The proposed universal filters offer the following advantageous features: using active elements for the same type (OFCC). No requirement for component matching or cancellation constraints, which makes the filter easier to design, orthogonal adjustment of ω0 and Q and the circuits have low sensitivity. The simulation and experimental results are obtained and discussed.

Adipose Stem Cells Display Higher Regenerative Capacities and More Adaptable Electro-Kinetic Properties Compared to Bone Marrow-Derived Mesenchymal Stromal Cells.

Adipose stem cells (ASCs) have recently emerged as a more viable source for clinical applications, compared to bone-marrow mesenchymal stromal cells (BM-MSCs) because of their abundance and easy access. In this study we evaluated the regenerative potency of ASCs compared to BM-MSCs. Furthermore, we compared the dielectric and electro-kinetic properties of both types of cells using a novel Dielectrophoresis (DEP) microfluidic platform based on a printed circuit board (PCB) technology. Our data show that ASCs were more effective than BM-MSCs in promoting neovascularization in an animal model of hind-limb ischemia. When compared to BM-MSCs, ASCs displayed higher resistance to hypoxia-induced apoptosis, and to oxidative stress-induced senescence, and showed more potent proangiogenic activity. mRNA expression analysis showed that ASCs had a higher expression of Oct4 and VEGF than BM-MSCs. Furthermore, ASCs showed a remarkably higher telomerase activity. Analysis of the electro-kinetic properties showed that ASCs displayed different traveling wave velocity and rotational speed compared to BM-MSCs. Interestingly, ASCs seem to develop an adaptive response when exposed to repeated electric field stimulation. These data provide new insights into the physiology of ASCs, and evidence to their potential superior potency compared to marrow MSCs as a source of stem cells.

A novel pH sensor using differential ISFET current mode read-out circuit

This paper presents a novel differential current mode read-out circuit for the Ion Sensitive Field Effect Transistor (ISFET), as a pH sensor. It uses six Operational Floating Current Conveyors (OFCC), and provides linear sensitivity to pH over a wide range (pH values 2-12). Moreover, it provides an output current that is linearly related to the differential voltage between the ISFET and the Reference Field Effect Transistor (REFET) sensors. The proposed read-out circuit uses only one type of active element (i.e. an OFCC) that makes this circuit easier to be both integrated and fabricated using a conventional CMOS process. Our experimental and simulation results demonstrate that the read-out circuit works reliably and can be a suitable sensor read-out circuit for lab on chip biomedical applications. The read-out circuit connected with the system composed of the ISFET and REFET sensors also reduces the impact of the parameter fluctuations and environment conditions on the performance of the ISFET sensor.

A Novel Nondestructive Read/Write Circuit for Memristor-Based Memory Arrays

Emerging nonvolatile universal memory technology is vital for providing the huge storage capabilities, which is needed for nanocomputing facilities. Memristor, which is recently discovered and known as the missing fourth circuit element, is a potential candidate for the next-generation memory. Memristor has received extra attention in the last few years. To support this effort, this paper presents a novel read/write circuit that facilitates the reading and writing operation of the Memristor device as a memory element. The advantages of the proposed read/write circuit are threefold. First, the proposed circuit has a nondestructive successive reading cycle capability. Second, it occupies less die area. Finally, the proposed read/write circuit offers a significant improvement in power consumption and delay time compared with other read/write circuits.

CMOS Based Lab-on-a-Chip: Applications, Challenges and Future Trends

Lab-on-a-chip is a technology which changed the traditional way by which biological samples are inspected in laboratories during analyses. This technology promises many advantages including better and improved performance, portability, reliability and cost reduction. A Lab-on-a-chip is composed of three main parts; actuation, sensing and electronics. Typically, hybrid technologies are used for the three parts, representing difficulties in integration and increased cost. However, Complementary Metal Oxide Semiconductor (CMOS) technology allows the functional integration of all parts including sensors, signal conditioning and processing circuits using a single homogeneous technology to develop a fully integrated lab-on-a-chip. CMOS technology is a very well established mass production and cheap technology. Hence, any viable lab-on-a-chip based on CMOS technology will have direct commercial value and application. This article, therefore, focuses on a survey of the most common CMOS based lab-on-a-chip techniques. Also, this article presents and discusses the features of existing CMOS based lab-on-a-chips and their applications at the cell level. Moreover, this article covers the challenges and the future trends in CMOS based lab-on-a-chip technology.

Lab on a Chip Based on CMOS Technology: System Architectures, Microfluidic Packaging, and Challenges

This article is a survey of the most common lab-on-a-chip techniques based on CMOS technology. It also presents different microfluidic packaging techniques that are used in the currently used lab on a chip based on CMOS technology.

A new second-order active universal filter with single input and three outputs using operational floating current conveyor

A new active universal filter with single input and three outputs using Operational Floating Current Conveyor (OFCC) is presented. The configuration uses four OFCC, two grounded capacitors and three resistors. The proposed filter offers the following advantageous: (1) Using active elements of the same type (four OFCC). (2) Realization of low pass, band pass and high pass, filters simultaneously. (3) No requirements for component matching conditions or cancellation constraints, which makes the universal filter easier to design. (4) Orthogonal adjustment of /spl omega//sub 0/ and Q. (5) the circuit has low sensitivity to passive components, (6) using active elements of the same type (four OFCC) and (7) all the passive elements are grounded. The simulation results show that the proposed filter performs its functions properly.