A Multi-Ion Super-Nernstian Sensing Platform Based on MoS₂ Near-Sensor Amplifiers.

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Accurate measurement of multiple ions in biofluids is vital for healthcare.
• Ion-sensitive field-effect transistors offer label-free, low-cost sensing but are limited by the Nernst limit.
• Existing methods to overcome the Nernst limit lack integration or stability.

Purpose of the Study:

• To develop a multi-ion super-Nernstian sensing platform overcoming the Nernst limit.
• To enhance sensitivity and stability in ion detection using near-sensor amplification.
• To enable advanced point-of-care diagnostics through improved ion measurement.

Main Methods:

• Coupling a molybdenum disulfide (MoS₂) inverter array with a multi-ion sensor chip in an extended-gate configuration.
• Utilizing the high gain and stability of MoS₂ inverters, facilitated by graphene and hexagonal boron nitride (h-BN).
• Demonstrating in situ amplification for super-Nernstian ion detection.

Main Results:

• Achieved super-Nernstian detection of pH, Na⁺, K⁺, and Ca²⁺ in biofluid ranges.
• Demonstrated stable long-term responses and selectivity.
• Validated platform practicality through artificial sweat analysis.

Conclusions:

• The proposed MoS₂-based inverter amplifier enables super-Nernstian ion sensing, surpassing the Nernst limit.
• The platform offers high sensitivity, stability, and practicality for biofluid analysis.
• This approach is promising for point-of-care diagnostics and near-sensor computing applications.