An FET-type charge sensor for highly sensitive detection of DNA sequence

Area of Science:

• Semiconductor device physics
• Biomolecular electronics
• Nanotechnology

Background:

• Field-effect transistors (FETs) are sensitive to surface charge variations.
• Deoxyribonucleic acid (DNA) possesses a negative charge due to its phosphate backbone.
• Detecting DNA immobilization and hybridization is crucial for molecular diagnostics.

Purpose of the Study:

• To fabricate and characterize a FET-type DNA charge sensor using standard CMOS technology.
• To investigate the sensor's ability to detect DNA probe immobilization and hybridization.
• To confirm the sensor's performance through electrical measurements and quartz crystal microbalance (QCM) analysis.

Main Methods:

• Fabrication of a p-channel MOSFET-based FET-type DNA sensor using 0.5 microm CMOS technology.
• Immobilization of thiol-modified DNA onto a gold gate electrode.
• Measurement of drain current variations upon injection of DNA solutions.
• Validation of results using quartz crystal microbalance (QCM) for mass change detection.

Main Results:

• The FET-type DNA sensor successfully detected DNA probe immobilization and hybridization.
• Drain current increased upon injection of thiol DNA and target DNA, correlating with DNA charge.
• Electrical characteristics demonstrated the field effect mechanism influenced by DNA charge.
• QCM results corroborated the mass changes associated with DNA binding.

Conclusions:

• The developed FET-type DNA charge sensor effectively detects DNA sequences via drain current variations.
• The sensor leverages the field effect mechanism driven by the inherent charge of DNA molecules.
• This CMOS-compatible sensor shows significant potential for the development of advanced DNA chips and biosensing platforms.