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Synthesis of TiO*2 structure at low hydrothermal temperature for biosensor application

2018-12 , Mayasarah Fauzan , Nur Hamidah Abdul Halim , Nurul Bariah Idris , Y. S. Lee , Sharipah Nadzirah Syed Ahmad Ayob

Synthesis of TiO₂ wires was prepared by using two steps method. TiO₂ seed layer was prepared using sol-gel method while TiO₂ wires were grown by using hydrothermal method. The annealing time and temperature during hydrothermal method were varied from 1, 4, and 5 hours and 110 and 120 °C respectively to analyze the effect towards the growth of TiO₂ wires. The morphology of TiO₂ wires formed was characterized using scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The electrical characterization of the TiO₂ wire based biosensor was conducted using electrochemical analysis. The cyclic voltammetry response was observed to analyze the performance of the glucose biosensor. The TiO₂ wires have shown a good response towards glucose detection.

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Electrical simulation on silicon nanowire field-effect transistor biosensor at different substrate-gate voltage bias conditions for charge detection

2022-12 , X.Y. Teoh , Mohamad Faris Mohamad Fathil , Y.M.Tan , Norhayati Sabani , Mohammad Nuzaihan Md Nor , Mohd Khairuddin Md Arshad , Ruslinda A. Rahim , Nur Hamidah Abdul Halim , Ramzan Mat Ayub , Uda Hashim , M.M. Ibrahim

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.

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Fabrication and simulation of silicon nanowire pH sensor for Diabetes Mellitus detection

2023-04 , C. Y. Chean , Mohammad Nuzaihan Md Nor , Mohamad Faris Mohamad Fathil , M. I. Hashim , Nur Hamidah Abdul Halim , Zarimawaty Zailan , Mohd Khairuddin Md Arshad , Syamsul Syahrun Awang@Hashim , Rozaimah A.T

Diabetes Mellitus (DM) is a disease failed to control the balance of blood sugar level due to lack of insulin thereby it effect human health. In Malaysia, there are around 3.9 millions people aged 18 years old and above have diabetes according to National Health and Morbidity Survey 2019. Silicon Nanowire is a nanostructure which has ultra-high sensitivity and non-radioactive that has potential given good performances when applied on pH sensor and biosensor. Silicon nanowire pH sensor and biosensor is an electronic sensor that investigated to improve the sensitivity and accuracy for detecting DM. This project consists of two parts, which are fabrication of silicon nanowire pH sensor and simulation of silicon nanowire biosensor as preliminary study. In fabrication, silicon nanowire of pH sensor is fabricated by conventional lithography process, reaction ion etching (RIE) and metallization to achieved the width of 100 nm silicon nanowire. The pH6, pH7, pH10 and DI water as analytes to analysis the current-voltage (I-V) characteristics of silicon nanowire pH sensor. In second part, the silicon nanowire biosensor as preliminary study is done simulation by Silvaco ATLAS devices simulator. The silicon nanowire with 30 nm in height and 20 nm in width of biosensor is designed and simulated to analyze the performance in terms of sensitivity. I-V characteristics of silicon nanowire biosensor according to different concentration of negative interface charge is determined. The negative interface charge represent as the Retinol Binding Protein 4 (RBP4) which is used to diagnose DM. The I-V characteristic based on the change in current, resistance and conductance to determine sensitivity. Lastly, the sensitivity of silicon nanowire pH sensor obtained 23.9 pS/pH while the sensitivity of simulated silicon nanowire biosensor obtained 3.91 nS/e.cm2. The results shown the more negative charge of concentration analyte attached on surface silicon nanowire has been accumulated more current flow from drain terminal to source terminal. It leads to the resistance becomes highest and obtained good sensitivity. In summary, the silicon nanowire pH sensor exhibited good performance and high sensitivity in detection pH level. The simulated silicon nanowire biosensor is capable of detecting biomolecular interactions charges to obtained high sensitive and accuracy result.