A 30.3 fA/√Hz Biosensing Current Front-End With 139 dB Cross-Scale Dynamic Range

Area of Science:

• Electronics
• Biotechnology
• Spectroscopy

Background:

• Electrochemical sensors require sensitive current-sensing front-ends for biomolecular detection.
• Existing analog front-ends (AFEs) often face limitations in sensitivity, dynamic range, and power efficiency.
• Label-free and immobilization-free biosensing techniques are crucial for real-time molecular interaction studies.

Purpose of the Study:

• To develop a high-sensitivity, low-noise 8-channel analog front-end (AFE) for on-chip microelectrode electrochemical sensors.
• To achieve efficient and accurate real-time monitoring of protein-ligand interactions.
• To demonstrate the utility of a novel biosensing platform using transient induced molecular electronic spectroscopy (TIMES).

Main Methods:

• Designed an 8-channel array featuring low-noise (30.3 fA/√Hz) current sensing front-ends.
• Implemented a 1st-order continuous-time delta-sigma (CT ΔΣ) modulator for high sensitivity (123 fA) and dynamic range (139 dB).
• Utilized a digital predictor and tri-level pulse width modulated (PWM) current-steering DAC for area- and power-efficient operation.

Main Results:

• Achieved a sensitivity of 123 fA over a 10 Hz bandwidth with a 139 dB cross-scale dynamic range.
• The AFE demonstrated low power consumption (50.3 µW) and small area (0.11 mm²) per channel.
• Successfully observed protein-ligand interactions in real-time using the TIMES technique.

Conclusions:

• The proposed 8-channel AFE offers a highly sensitive and efficient solution for electrochemical biosensing.
• The developed platform enables label- and immobilization-free real-time monitoring of molecular interactions.
• This technology advances biosensing capabilities for applications in molecular diagnostics and research.