Silicon Nanowires Length and Numbers Dependence on Sensitivity of the Field-Effect Transistor Sensor for Hepatitis B Virus Surface Antigen Detection

Abstract

Silicon nanowire field effect transistor (NWFET) sensors have been demonstrated to have high sensitivity, are label free, and offer specific detection. This study explored the effect of nanowire dimensions on sensors’ sensitivity. We used sidewall spacer etching to fabricate polycrystalline silicon NWFET sensors. This method does not require expensive nanoscale exposure systems and reduces fabrication costs. We designed transistor sensors with nanowires of various lengths and numbers. Hepatitis B surface antigen (HBsAg) was used as the sensing target to explore the relationships of nanowire length and number with biomolecule detection. The experimental results revealed that the sensor with a 3 µm nanowire exhibited high sensitivity in detecting low concentrations of HBsAg. However, the sensor reached saturation when the biomolecule concentration exceeded 800 fg/mL. Sensors with 1.6 and 5 µm nanowires exhibited favorable linear sensing ranges at concentrations from 800 ag/mL to 800 pg/mL. The results regarding the number of nanowires revealed that the use of few nanowires in transistor sensors increases sensitivity. The results demonstrate the effects of nanowire dimensions on the silicon NWFET biosensors.

Polycrystalline Silicon Nanowire Field Effect Transistor Biosensors for SARS-CoV-2 Detection

“…1f). 29 The greatest advantage of this technique is its selfalignment ability. With well-controlled etching parameters, this enabled the production of nanowires less than 100 nm in diameter.…”

“…That is, they can be mass-produced to reduce costs and miniaturized to fabricate portable multifunctional biosensors. 29 In this study, a polycrystalline silicon (poly-Si) NWFET biosensor was developed for SARS-CoV-2 detection. As opposed to monocrystalline silicon nanowire, in which expensive silicon-oninsulator chips must be used, ordinary silicon chips can be used as the substrate in poly-Si nanowire devices, greatly reducing manufacturing costs.…”

Application and prospect of semiconductor biosensors in detection of viral zoonoses

“…Furthermore, the chemical functionalization techniques of the pSiNWFET surface were performed for the immobilization of the relevant antibodies for sensing the HBV-related biomarkers such as HBsAg and HBx proteins. These semiconductor biosensors can detect the HBsAg and HBx proteins at the femto-molar level providing an opportunity to evaluate and understand hepatitis infection [40,57] Uhme et al [58] demonstrated that the ultrasensitive electrical detection of the HA1 domain of hemagglutinin (HA), a representative viral surface protein of the influenza virus, using the top-down complementary metal oxide semiconductor (CMOS) processed silicon nanowire (SiNW) field-effect transistor (FET) configuration. Femtomolar concentrations of HA1 can be detected (ΔV T = 63 mV/dec, ΔV T = 112 mV at 1 fM HA1) by virtue of the stable and efficient cytidine-5′-monophospho-N-acetylneuraminic acid(CMP-NANA) probe and intermediate glutaraldehyde(GA) linker, and the high surfaceto-volume ratio of the SiNWs [58] Wu et al used sidewall spacer to fabricate polycrystalline silicon NWFET sensors.…”

Estimation of the Depletion Layer Thickness in Silicon Nanowire-Based Biosensors from Attomolar-Level Biomolecular Detection

“…To further advance the detection properties of SiNW biosensors, the effects of various critical components on the sensitivity (including the NW structure, , functionalization method, electrolyte ion concentration, , and analyte delivery system) have been investigated by numerous theoretical and experimental studies. The SiNW surface functionalization and biorecognition elements are crucial for the sensitivity and selectivity progress.…”

“…They demonstrated that device sensitivity increases with decreasing number of NWs, narrower NW diameters, and lower NW doping densities. Wu 21 analyzed the NW length and number dependence on the sensitivity of the SiNW biosensor and found that sensitivity can be increased by using few SiNWs in biosensors. Owing to these reports, the dependence of NW width, length, number, and doping density on sensitivity has been revealed and investigated.…”