Offset-free differential-mode bio-sensing system using dual mosfets with au gate

This paper presents a differential-mode bio-sensing system using dual MOSFETs with Au gate for the detection of biomolecules. FET-based biosensors have attractive merits. For example, they can be fabricated by a standard CMOS process. However, when FET-based biosensors detect biomolecules, they are exposed to environmental factors which influence them as interference. To reduce interferences of biosensors such as light, temperature and drift, a conventional differentialmode system is used which is composed of a BioFET with Au gate and a REFET with Pt gate. However, using Pt as the gate metal for REFET has disadvantages such as chemical instability and unwanted immobilization of certain biomoleculeson the Pt surface. Therefore, we developed a differential mode bio-sensing system in which Au gate was used for both BioFET and REFET. Variation of the output voltage was measured after streptavidin-biotin reaction. Elimination of common-mode signal was observed and offset-free operation of the differential mode bio-sensing system was confirmed.