Electrical detection Archives – Institute of Nano Electronic Engineering

Abstract – In this research, a silicon nanogap biosensor has the potential to play a significant role in the field of biosensors for detecting Retinol Binding Protein 4 (RBP4) molecules due to its unique nanostructure morphology, biocompatibility features, and electrical capabilities. Additionally, as preliminary research for RBP4, a silicon nanogap biosensor with unique molecular gate control for pH measurement was developed. Firstly, using conventional lithography followed by the Reactive-ion etching (RIE) technique, a nanofabrication approach was utilized to produce silicon nanogaps from silicon-on-insulator (SOI) wafers. The critical aspects contributing to the process and size reduction procedures were highlighted to achieve nanometer-scale size. The resulting silicon nanogaps, ranging from 100 nm to 200 nm, were fabricated precisely on the device. Secondly, pH level detection was performed using several types of standard aqueous pH buffer solutions (pH 6, pH 7, pH 12) to test the electrical response of the device. The sensitivity of the silicon nanogap pH sensor was 7.66 pS/pH (R² = 0.97), indicating that the device has a wide range of pH detecting capacity. This also includes the silicon nanogap biosensor validated by simulation, with the sensitivity obtained being 3.24 μA/e.cm² (R² = 0.98). The simulation of the sensitivity is based on the interface charge (Qf) that represents the concentration of RBP4. The results reveal that the silicon nanogap biosensor has excellent characteristics for detecting pH levels and RBP4 with outstanding sensitivity performance. In conclusion, this silicon nanogap biosensor can be used as a new electrical RBP4 biosensor for biomedical diagnostic applications in the future.

Corresponding Author: Assoc. Prof. Dr. Mohammad Nuzaihan Md Nor
Corresponding Author’s Email: m.nuzaihan@unimap.edu.my

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Link to Publication: https://doi.org/10.58915/ijneam.v17iJune.830

Abstract – In this paper, a silicon nanowire biosensor with novel molecular gate control has been demonstrated for Deoxyribonucleic acid (DNA) detection related to dengue virus (DENV). The silicon nanowire was fabricated using the top-down nanolithography approach, through nanostructuring of silicon-on-insulator (SOI) layers achieved by combination of the electron-beam lithography (EBL), plasma dry etching and size reduction processes. The surface of the fabricated silicon nanowire was functionalized by means of a three-step procedure involving surface modification, DNA immobilization and hybridization. This procedure acts as a molecular gate control to establish the electrical detection for 27-mers base targets DENV DNA oligomer. The electrical detection is based on the changes in current, resistance and conductance of the sensor due to accumulation of negative charges added by the immobilized probe DNA and hybridized target DNA. The sensitivity of the silicon nanowire biosensors attained was 45.0 μA M-1, which shows a wide-range detection capability of the sensor with respect to DNA. The limit of detection (LOD) achieved was approximately 2.0 fM. The demonstrated results show that the silicon nanowire has excellent properties for detection of DENV with outstanding repeatability and reproducibility performances.

Keywords – Dengue fever (DF); Deoxyribonucleic acid (DNA); Electrical detection; Molecular gate control; Nanolithography; Silicon nanowire biosensor

Corresponding Author: Mohammad Nuzaihan Md Nor
Corresponding Author’s Email: m.nuzaihan@unimap.edu.my

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Fabrication and simulation of silicon nanogaps pH sensor as preliminary study for Retinol Binding Protein 4 (RBP4) detection

Electrical detection of dengue virus (DENV) DNA oligomer using silicon nanowire biosensor with novel molecular gate control