Now showing 1 - 10 of 26
  • Publication
    Field-Effect Transistor-based Biosensor Optimization: Single Versus Array Silicon Nanowires Configuration
    ( 2020-01-01)
    Ong C.C.
    ;
    ; ; ; ; ;
    Rafizatul Fitri Abdullah
    ;
    Mohd Hazmi Mohd Ghazali
    ;
    Tamjis N.
    This paper demonstrated the effect of different number of silicon nanowire transducer channels, in other word single, double, and triple channels towards the performance of field-effect transistor-based biosensor through simulation tool. These silicon nanowire field-effect transistor biosensors were designed and simulated in device simulation modelling tool, Silvaco ATLAS with fixed length, width, and height of the silicon nanowire. Different negatively interface charge density values were applied on the transducer channels’ surface of the biosensors to represent as detected target biomolecules that will bind onto the surface of the transducer regions. Based on the results, more negatively interface charges density values presented on the sensing channels had reduced the electron carrier accumulation at the channel’s interface, therefore, reduced drain current flow between the source and drain terminal. With the increase number of the transducer channels, significant change in drain current for every applied negatively interface charges became more apparent and increased the sensitivity of the biosensor. The triple transducer channels silicon nanowire field-effect transistor biosensor had demonstrated highest sensitivity, that is 2.83 µA/e∙cm2, which indicates it has better response for the detection of interface charges, thus increases chances for transducer channels reaction to the target biomolecules during testing or diagnosis.
  • Publication
    Impact of buried oxide thickness in substrate-gate integrated silicon nanowire field-effect transistor biosensor performance for charge sensing
    The paper investigated on performance in charge sensing for substrate-gate integrated silicon nanowire field-effect transistor biosensor at different thickness of the buried oxide layer, sandwiched in between the top-silicon and substrate layers. The device structures with different buried oxide thickness ranging from 100 to 200 nm were designed and simulated using the Silvaco ATLAS device simulation software. The increase of buried oxide thickness reduced the strength of induced electric field that contributes to the formation of inversion layer for current flow through the silicon nanowire channel, hence contributed to the increase in threshold voltage. For simulation of charge sensing, the device demonstrated the ability to identify different interface charge values ranging from -5×1010 to -9×1010 e· cm-2 applied on the surface of the silicon nanowire channel to represent target charge biomolecules that bound to the biosensor in actual detection. Significant change in threshold voltage can be observed due to the applied interface charge density values and was evaluated to determine the sensitivity for charge sensing performance. The device shows better performance when designed with buried oxide thickness of 200 nm at sensitivity of 1.151 V/e· cm-2.
  • Publication
    Integration of microfluidic channel on electrochemical-based nanobiosensors for monoplex and multiplex analyses: An overview
    ( 2023-05-01)
    Adam H.
    ;
    ; ;
    Adam T.
    ;
    ; ;
    Fakhri M.A.
    ;
    Subramaniam S.
    ;
    Chen Y.
    ;
    Sasidharan S.
    ;
    Wu Y.S.
    Background: Microfluidic devices have evolved into low-cost, simple, and powerful analytical tool platforms. Herein, an electrochemically-based microfluidic nanobiosensor array for monoplex and multiplex detection of physiologically relevant analytes is reviewed. Unlike other analyte detection methods, microfluidics-based embedded electrochemical nanobiosensors are portable, custom electrochemical readers for signal reading. Methods: Microfluidic devices and electrochemical sensors can be integrated into monoplex or multiplex systems. The integrated system is simple to use and sensitive, and so has great potential as a powerful tool for profiling immune-mediated treatment responses in real time. It may also be developed further as a point-of-care diagnostic device for conducting near-patient tests using biological samples. Therefore, using mutiplex analysis, a biosensor array may detect multiple analytes in a sample solution and provide different outputs for each analyte. A microfluidic electrochemical nanobiosensor, for example, can detect urine glucose, lactate, and uric acid. The microfluidic array of integrated nanobiosensors and electrochemical sensors enables fast and cost-effective selection of high-quality and statistically significant diagnostic data at the point of care. The multiplex analytical test is an important molecular tool for academic research as well as clinical diagnosis. Although key approaches for analysing numerous analytes have been developed, none of them are suitable for point-of-care diagnostics, especially in situations with limited resources. Significant findings: In this study, monoplex and multiplex microfluidic assays for rapid measurement of single and multiple analytes at the point of care are presented. Since this test can analyse both single and multiple analytes, it is exceptionally specific, easy to use, and inexpensive. The ability of integrated electrochemical-based microfluidic devices with single channel and multiple channels systems to perform monoplex and multiplex analysis simultaneously and independently is the novelty of this review.
      2
  • Publication
    Selective detection of amyloid fibrils by a dipole moment mechanism on dielectrode – Structural insights by in silico analysis
    ( 2023-03-01)
    Adam H.
    ;
    ;
    Kumarevel T.
    ;
    ;
    Adam T.
    ;
    ;
    Subramaniam S.
    ;
    ;
    Chen Y.
    Amyloid fibrils are associated with different neurodegenerative diseases, a final product of several protein aggregation pathways. Parkinson's disease is a type of amyloidosis, characterized by the accumulation and propagation of amyloid fibrils of alpha-synuclein. The detection of fibrils at low concentrations is critical for the diagnosis of Parkinson's disease. We report a novel technique for the selective detection of amyloid fibrils through a dipole moment on a dielectrode surface. A sensitive dielectrode sensor for detecting aggregation of alpha synuclein and works by interacting an antibody on two-electrode surface functionalized gold interdigitated electrode. For the physical characterization of the sensing surface and finger electrodes, high-power microscope, scanning electron microscope, and 3D-profilormeter were used. Electrical characterization was performed on the sensing surface by using Keithley 6487 picoammeter. Based on the stability analysis with various electrolytes solutions, the sensor was found to be stable from pH 3. Further, under optimal circumstances, a linear range of alpha synuclein fibril detection was from 100 aM to 100 pM [y = 5E-06x + 5E-06; R² = 0.9724], and the limit of detection was estimated to be 100 aM based on S/N = 3. This study was further anchored by molecular docking analysis with synuclein peptide (47−56). We predict that advancements in this direction will assist in clarifying the complex process posed by Parkinson's disease.
      2
  • Publication
    The impact of silicon nanowire transducer channel width on field-effect transistor biosensor performance
    This paper reported on performance assessment of a field-effect transistor-based biosensor with different widths of the silicon nanowire transducer channel. Silvaco ATLAS device simulation software was used to model the device design with three different channel widths, which are 100, 150, and 200 nm. In this simulation, the bounded target biomolecules during actual detection using the biosensor were represented by several negative interface charge density values applied on the surface of the transducer channel. Increase in accumulation of hole carriers beneath the channel's surface was observed due to the availability of negative interface charges on the surface, hence increased the output drain current. Furthermore, width reduction of the device's channel had allowed more significant change in drain current due to application of different interface charge density values and increased the device's sensitivity. Among the simulated devices, silicon nanowire field-effect transistor-based biosensor with transducer channel width of 100 nm had shown highest sensitivity (-56.45 nA/e.cm2) with lowest interface charge density detection (2.79u1010 e/cm-2), which means it enhances the interface charge detection by providing better response and allows lower limit of detection. Therefore, in actual detection, possibility for reaction of the transducer channel to the specific target biomolecule can be increased.
      1  19
  • Publication
    Distinguishing normal and aggregated alpha-synuclein interaction on gold nanorod incorporated zinc oxide nanocomposite by electrochemical technique
    Misfolding and accumulation of the protein alpha synuclein in the brain cells characterize Parkinson's disease (PD). Electrochemical based aluminum interdigitated electrodes (ALIDEs) was fabricated by using conventional photolithography method and modified the surfaces with zinc oxide and gold nanorod by using spin coating method for the analysis of PD protein biomarker. The device surface modified with gold nanorod of 25 nm diameter was used. The bare devices and the surface modified devices were characterized by Scanning Electron Microscope, 3D-Profilometer, Atomic Force Microscope and high-power microscope. The above measurement was also performed to measure the interaction of antibody with aggregated alpha-synuclein for normal, aggregated and aggregated alpha synuclein in human serum and distinguished against 3 control proteins (PARK1, DJ-1 and Factor IX). The detection limit for normal alpha synuclein was 1 f. with the sensitivity of 1 f. on a linear regression (R2 = 0.9759). The detection limit for aggregated alpha synuclein was 10 aM with the sensitivity of 1 aM on a linear regression (R2 = 0.9797). Also, the detection limit of aggregated alpha synuclein in serum was 10 aM with the sensitivity of 1 aM on a linear regression (R2 = 0.9739). These results however indicate that, serum has only minimal amount of alpha synuclein.
      35  5
  • Publication
    Integration of microfluidic channel on electrochemical-based nanobiosensors for monoplex and multiplex analyses: An overview
    ( 2023-05-01)
    Adam H.
    ;
    ; ; ; ; ;
    Fakhri M.A.
    ;
    Subramaniam S.
    ;
    Chen Y.
    ;
    Sasidharan S.
    ;
    Wu Y.S.
    Background: Microfluidic devices have evolved into low-cost, simple, and powerful analytical tool platforms. Herein, an electrochemically-based microfluidic nanobiosensor array for monoplex and multiplex detection of physiologically relevant analytes is reviewed. Unlike other analyte detection methods, microfluidics-based embedded electrochemical nanobiosensors are portable, custom electrochemical readers for signal reading. Methods: Microfluidic devices and electrochemical sensors can be integrated into monoplex or multiplex systems. The integrated system is simple to use and sensitive, and so has great potential as a powerful tool for profiling immune-mediated treatment responses in real time. It may also be developed further as a point-of-care diagnostic device for conducting near-patient tests using biological samples. Therefore, using mutiplex analysis, a biosensor array may detect multiple analytes in a sample solution and provide different outputs for each analyte. A microfluidic electrochemical nanobiosensor, for example, can detect urine glucose, lactate, and uric acid. The microfluidic array of integrated nanobiosensors and electrochemical sensors enables fast and cost-effective selection of high-quality and statistically significant diagnostic data at the point of care. The multiplex analytical test is an important molecular tool for academic research as well as clinical diagnosis. Although key approaches for analysing numerous analytes have been developed, none of them are suitable for point-of-care diagnostics, especially in situations with limited resources. Significant findings: In this study, monoplex and multiplex microfluidic assays for rapid measurement of single and multiple analytes at the point of care are presented. Since this test can analyse both single and multiple analytes, it is exceptionally specific, easy to use, and inexpensive. The ability of integrated electrochemical-based microfluidic devices with single channel and multiple channels systems to perform monoplex and multiplex analysis simultaneously and independently is the novelty of this review.
      2
  • Publication
    Integration of microfluidic channel on electrochemical-based nanobiosensors for monoplex and multiplex analyses: An overview
    ( 2023-05-01)
    Adam H.
    ;
    ; ;
    Adam T.
    ;
    ; ;
    Fakhri M.A.
    ;
    Subramaniam S.
    ;
    Chen Y.
    ;
    Sasidharan S.
    ;
    Wu Y.S.
    Background: Microfluidic devices have evolved into low-cost, simple, and powerful analytical tool platforms. Herein, an electrochemically-based microfluidic nanobiosensor array for monoplex and multiplex detection of physiologically relevant analytes is reviewed. Unlike other analyte detection methods, microfluidics-based embedded electrochemical nanobiosensors are portable, custom electrochemical readers for signal reading. Methods: Microfluidic devices and electrochemical sensors can be integrated into monoplex or multiplex systems. The integrated system is simple to use and sensitive, and so has great potential as a powerful tool for profiling immune-mediated treatment responses in real time. It may also be developed further as a point-of-care diagnostic device for conducting near-patient tests using biological samples. Therefore, using mutiplex analysis, a biosensor array may detect multiple analytes in a sample solution and provide different outputs for each analyte. A microfluidic electrochemical nanobiosensor, for example, can detect urine glucose, lactate, and uric acid. The microfluidic array of integrated nanobiosensors and electrochemical sensors enables fast and cost-effective selection of high-quality and statistically significant diagnostic data at the point of care. The multiplex analytical test is an important molecular tool for academic research as well as clinical diagnosis. Although key approaches for analysing numerous analytes have been developed, none of them are suitable for point-of-care diagnostics, especially in situations with limited resources. Significant findings: In this study, monoplex and multiplex microfluidic assays for rapid measurement of single and multiple analytes at the point of care are presented. Since this test can analyse both single and multiple analytes, it is exceptionally specific, easy to use, and inexpensive. The ability of integrated electrochemical-based microfluidic devices with single channel and multiple channels systems to perform monoplex and multiplex analysis simultaneously and independently is the novelty of this review.
      2  24
  • Publication
    Electrical simulation on silicon nanowire field-effect transistor biosensor at different substrate-gate voltage bias conditions for charge detection
    In this work, the impact of different substrate-gate voltage bias conditions (below and above the device threshold voltage) on current-voltage characteristics and sensitivity of a silicon nanowire field-effect transistor (SiNW-FET) biosensor was investigated. A 3-dimensional device structure with n-type SiNW channel and a substrate gate electrode was designed and electrically simulated In the Silvaco ATLAS. Next, the SiNW channel was covered with a range of interface charge density to mimic the charged target biomolecule captured by the device. The outcome was translated into a drain current versus interface charge semi-log graph and the device sensitivity was calculated using the linear regression curve’s slope of the plotted data. The device’s electrical characteristic shown higher generation of output drain current values with the increase of negative substrate-gate voltage bias due to the hole carriers’ accumulation that forms a conduction channel in the SiNW. Application of higher negative interface charge density increased the change in drain current, with the device biased with higher substrate-gate voltage shows more significant change in drain current. The device sensitivity increased when biased with higher substrate-gate voltage with highest sensitivity is 75.12 nA/dec at substrate-gate voltage bias of –1.00 V.
      3  62
  • Publication
    Formation of polypropylene nanocomposite joint using silicon carbide nanowhiskers as novel susceptor for microwave welding
    Up to present, no study has reported on the use of silicon carbide nanomaterials (SiCNMs) as susceptor for microwave welding of thermoplastics. Therefore, in this study, silicon carbide nanowhiskers (SiCNWs) was attempted as the microwave susceptor for the microwave welding of polypropylene (PP). It was observed that SiCNWs are capable of absorbing microwave and converting them into heat, leading to a sharp increase in temperature until it reaches the melting point of PP substrates. The microwave welded joint is formed after the molten PP at the interface between PP substrates is cooled under pressure. The effect of microwave heating duration and solid loading of SiCNWs suspension was studied and reported. The formation mechanism of SiCNWs reinforced PP welded joint was proposed in this study. With these remarkable advantages of microwave welding and enhanced mechanical properties of the welded joint, it is believed that this study can provide a new insight into welding of thermoplastic and material processing through short-term microwave heating.
      26  1