Muhammad Asraf Mansor

Bio: Muhammad Asraf Mansor is an academic researcher from Universiti Teknologi Malaysia. The author has contributed to research in topics: Hough transform & Single-cell analysis. The author has an hindex of 4, co-authored 8 publications receiving 139 citations.

Single Cell Electrical Characterization Techniques

Abstract: Electrical properties of living cells have been proven to play significant roles in understanding of various biological activities including disease progression both at the cellular and molecular levels. Since two decades ago, many researchers have developed tools to analyze the cell's electrical states especially in single cell analysis (SCA). In depth analysis and more fully described activities of cell differentiation and cancer can only be accomplished with single cell analysis. This growing interest was supported by the emergence of various microfluidic techniques to fulfill high precisions screening, reduced equipment cost and low analysis time for characterization of the single cell's electrical properties, as compared to classical bulky technique. This paper presents a historical review of single cell electrical properties analysis development from classical techniques to recent advances in microfluidic techniques. Technical details of the different microfluidic techniques are highlighted, and the advantages and limitations of various microfluidic devices are discussed.

Red blood cells estimation using hough transform technique

Abstract: The number of red blood cells contributes more to clinical diagnosis with respect to blood diseases The aim of this research is to produce a computer vision system that can detect and estimate the number of red blood cells in the blood sample image Morphological is a very powerful tool in image processing, and it is been used to segment and extract the red blood cells from the background and other cells The algorithm used features such as shape of red blood cells for counting process, and Hough transform is introduced in this process The result presented here is based on images with normal blood cells The tested data consists of 10 samples and produced the accurate estimation rate closest to 96% from manual counting

Electrical impedance spectroscopy for detection of cells in suspensions using microfluidic device with integrated microneedles

Abstract: In this study, we introduce novel method of flow cytometry for cell detection based on impedance measurements. The state of the art method for impedance flow cytometry detection utilizes an embedded electrode in the microfluidic to perform measurement of electrical impedance of the presence of cells at the sensing area. Nonetheless, this method requires an expensive and complicated electrode fabrication process. Furthermore, reuse of the fabricated electrode also requires an intensive and tedious cleaning process. Due to that, we present a microfluidic device with integrated microneedles. The two microneedles are placed at the half height of the microchannel for cell detection and electrical measurement. A commercially-available Tungsten needle was utilized for the microneedles. The microneedles are easily removed from the disposable PDMS (Polydimethylsiloxane) microchannel and can be reused with a simple cleaning process, such as washing by ultrasonic cleaning. Although this device was low cost, it preserves the core functionality of the sensor, which is capable of detecting passing cells at the sensing area. Therefore, this device is suitable for low-cost medical and food safety screening and testing process in developing countries.

A novel integrated dual microneedle-microfluidic impedance flow cytometry for cells detection in suspensions

Abstract: In this study, a new, simple and cost-effective impedance detection of yeast cell concentration by using a novel integrated dual microneedle-microfluidic impedance flow cytometry was introduced. The reported method for impedance flow cytometry detection utilizes embedded electrode and probe in the microfluidic device to perform measurement of electrical impedance when a presence of cells at sensing area. Nonetheless, this method requires costly and complicatedly fabrication process of electrode. Furthermore, to reuse the fabricated electrode, it also requires intensive and tedious cleaning process. Due to that, a dual microneedle integrated at the half height of the microchannel for cell detection as well as for electrical measurement was demonstrated. A commercial available Tungsten needle was utilized as a dual microneedle. The microneedle was easy to be removed from the disposable PDMS microchannel and can be reused with the simple cleaning process, such as washed by using ultrasonic cleaning. Although this device was low cost, it preserves the core functionality of the sensor, which is capable of detecting the passing cells at sensing area. Therefore, this device is suitable for low cost medical and food safety screening and testing process in developing countries.

Platforms for Single-Cell Collection and Analysis.

Abstract: Single-cell analysis has become an established method to study cell heterogeneity and for rare cell characterization. Despite the high cost and technical constraints, applications are increasing every year in all fields of biology. Following the trend, there is a tremendous development of tools for single-cell analysis, especially in the RNA sequencing field. Every improvement increases sensitivity and throughput. Collecting a large amount of data also stimulates the development of new approaches for bioinformatic analysis and interpretation. However, the essential requirement for any analysis is the collection of single cells of high quality. The single-cell isolation must be fast, effective, and gentle to maintain the native expression profiles. Classical methods for single-cell isolation are micromanipulation, microdissection, and fluorescence-activated cell sorting (FACS). In the last decade several new and highly efficient approaches have been developed, which not just supplement but may fully replace the traditional ones. These new techniques are based on microfluidic chips, droplets, micro-well plates, and automatic collection of cells using capillaries, magnets, an electric field, or a punching probe. In this review we summarize the current methods and developments in this field. We discuss the advantages of the different commercially available platforms and their applicability, and also provide remarks on future developments.

Review and perspectives on microfluidic flow cytometers

Abstract: Modern microflow cytometers are sophisticated instruments capable of measuring multiple physical characteristics of a single cell simultaneously as the cells flow in suspension through a measuring device. Cytometers are the tool of choice for the high-speed acquisition and analysis of large single cell populations. However, traditional devices lack the ability to provide intracellular spatial information. In the past few decades, various flow cytometer systems with the ability to combine cell/particle detection and the acquisition of two or three-dimensional spatial information have been proposed. However, these devices suffer a number of drawbacks Accordingly, the problem of developing more sophisticated microflow cytometers based on electrical impedance, optical detection and image analysis methods has received significant attention in the literature. This review describes some of the major advances made in the microfluidic cytometry field over the past ten years. The review focuses specifically on recent proposals for enhanced microfluidic focusing techniques and detection/analysis methods, respectively. Overall, the review provides a useful insight into the microflow cytometer technology field for both new and existing users.

Single-cell microfluidic impedance cytometry: from raw signals to cell phenotypes using data analytics

Abstract: The biophysical analysis of single-cells by microfluidic impedance cytometry is emerging as a label-free and high-throughput means to stratify the heterogeneity of cellular systems based on their electrophysiology. Emerging applications range from fundamental life-science and drug assessment research to point-of-care diagnostics and precision medicine. Recently, novel chip designs and data analytic strategies are laying the foundation for multiparametric cell characterization and subpopulation distinction, which are essential to understand biological function, follow disease progression and monitor cell behaviour in microsystems. In this tutorial review, we present a comparative survey of the approaches to elucidate cellular and subcellular features from impedance cytometry data, covering the related subjects of device design, data analytics (i.e., signal processing, dielectric modelling, population clustering), and phenotyping applications. We give special emphasis to the exciting recent developments of the technique (timeframe 2017-2020) and provide our perspective on future challenges and directions. Its synergistic application with microfluidic separation, sensor science and machine learning can form an essential toolkit for label-free quantification and isolation of subpopulations to stratify heterogeneous biosystems.

Automatic Detection and Quantification of WBCs and RBCs Using Iterative Structured Circle Detection Algorithm

Abstract: Segmentation and counting of blood cells are considered as an important step that helps to extract features to diagnose some specific diseases like malaria or leukemia. The manual counting of white blood cells (WBCs) and red blood cells (RBCs) in microscopic images is an extremely tedious, time consuming, and inaccurate process. Automatic analysis will allow hematologist experts to perform faster and more accurately. The proposed method uses an iterative structured circle detection algorithm for the segmentation and counting of WBCs and RBCs. The separation of WBCs from RBCs was achieved by thresholding, and specific preprocessing steps were developed for each cell type. Counting was performed for each image using the proposed method based on modified circle detection, which automatically counted the cells. Several modifications were made to the basic (RCD) algorithm to solve the initialization problem, detecting irregular circles (cells), selecting the optimal circle from the candidate circles, determining the number of iterations in a fully dynamic way to enhance algorithm detection, and running time. The validation method used to determine segmentation accuracy was a quantitative analysis that included Precision, Recall, and F-measurement tests. The average accuracy of the proposed method was 95.3% for RBCs and 98.4% for WBCs.

Cell Cytometry: Review and Perspective on Biotechnological Advances.

Abstract: Cell identification and enumeration are essential procedures within clinical and research laboratories. For over 150 years, quantitative investigation of body fluids such as counts of various blood cells has been an important tool for diagnostic analysis. With the current evolution of point-of-care diagnostics and precision medicine, cheap and precise cell counting technologies are in demand. This article reviews the timeline and recent notable advancements in cell counting that have occurred as a result of improvements in sensing including optical and electrical technology, enhancements in image processing capabilities, and contributions of micro and nanotechnologies. Cell enumeration methods have evolved from the use of manual counting using a hemocytometer to automated cell counters capable of providing reliable counts with high precision and throughput. These developments have been enabled by the use of precision engineering, micro and nanotechnology approaches, automation and multivariate data analysis. Commercially available automated cell counters can be broadly classified into three categories based on the principle of detection namely, electrical impedance, optical analysis and image analysis. These technologies have many common scientific uses, such as hematological analysis, urine analysis and bacterial enumeration. In addition to commercially available technologies, future technological trends using lab-on-a-chip devices have been discussed in detail. Lab-on-a-chip platforms utilize the existing three detection technologies with innovative design changes utilizing advanced nano/microfabrication to produce customized devices suited to specific applications.