Liu Wei Wen
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Preferred name
Liu Wei Wen
Official Name
Wen, Liu Wei
Alternative Name
Liu, Wei Wen
Wei-Wen, Liu
Liu W., -W.
Main Affiliation
Scopus Author ID
57194266103
Researcher ID
D-2098-2015

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Fabrication of silicon nitride ion sensitive field-effect transistor for pH measurement and DNA Immobilization/Hybridization

2013 , Uda Hashim , Soon Weng Chong , Liu Wei Wen

The fabrication of ion sensitive field-effect transistor (ISFET) using silicon nitride (Si3N4) as the sensing membrane for pH measurement and DNA is reported. For the pH measurement, the Ag/AgCl electrode was used as the reference electrode, and different pH values of buffer solution were used in the ISFET analysis. The ISFET device was tested with pH buffer solutions of pH2, pH3, pH7, pH8, and pH9. The results show that the IV characteristic of ISFET devices is directly proportional and the device’s sensitivity was 43.13 mV/pH. The ISFET is modified chemically to allow the integration with biological element to form a biologically active field-effect transistor (BIOFET). It was found that the DNA immobilization activities which occurred on the sensing membrane caused the drain current to drop due to the negatively charged backbones of the DNA probes repelled electrons from accumulating at the conducting channel. The drain current was further decreased when the DNA hybridization took place.

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Precise alignment of individual single-walled carbon nanotube using dielectrophoresis method for development and fabrication of pH sensor

2013 , Uda Hashim , Foo Wah Low , Liu Wei Wen

Development and fabrication of single-walled carbon nanotube (SWNT) based pH sensor were reported. The precise alignment of individual SWNT using dielectrophoresis method between the two microgap electrodes was conducted, and the effects of precise alignment of individual SWNT on impedance, long term stability, and capacitance of the sensor were studied. The pH sensor was fabricated using conventional photolithography and wet etching process. The impedance values were found to decrease in the order of distilled water > pH 10 > pH 5 > pH 3 > air. Without the alignment of SWNT, the capacitances values decreased with increasing of pH values at low frequency. All the impedance and capacitance results were highly repeatable.

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