Reliable and highly sensitive biosensor from suspended MoS₂ atomic layer on nano-gap electrodes.

Area of Science:

• Materials Science
• Nanotechnology
• Biosensing

Background:

• Traditional 2D biosensors suffer from signal irregularity due to substrate-induced scattering and charge trapping.
• Suspended 2D materials offer potential but face challenges in reliability and selectivity.

Purpose of the Study:

• To demonstrate a novel fabrication method for suspended 2D-MoS2 biosensors using self-assembled nanogap electrodes.
• To evaluate the electrical characteristics and sensing capabilities of these suspended MoS2 field-effect transistors (FETs).

Main Methods:

• Fabrication of nanogap electrodes via self-assembly to suspend 2D-MoS2.
• Coating with Hafnium oxide (HfO2), linkers, and antibodies for functionalization.
• Electrical characterization of suspended MoS2 FETs using electrolyte gating.
• Detection of pH and Escherichia coli (E. coli) bacteria.

Main Results:

• Achieved a low subthreshold swing of 70 mV/dec and an ON/OFF ratio of 10^7 for suspended MoS2 FETs.
• Demonstrated high pH sensitivity (~880 per pH unit) and sensitive detection of E. coli (down to 10 CFU/mL).
• Exhibited consistent sensitivity across multiple fabricated devices.

Conclusions:

• The nanogap electrode approach successfully suspends 2D-MoS2, enhancing device robustness and electrical performance.
• The suspended MoS2 biosensor shows significant potential for sensitive and reliable detection of various biomolecules.
• This architecture could be extended for detecting biomarkers, including those for COVID-19.