FET-based biosensors with back-gate coupling towards the electrical pre-amplification of cardiac troponin I detection

The existing FET-based biosensors nowadays only depend on a physical structure size of a device. Due to those limitation, the device can only be read with the presence of high sensitivity electrical readers. To synchronize the device with a low-cost portable electrical reader, the electrical signal need to be amplified with minimal noise output. In this work, a label-free, specific and sensitive back-gated FET based biosensor is presented for the detection of cTnI protein by using SOI type of wafer with TiO2 act as a transducer material. TiO2 is deposited by using sol-gel method with surface functionalized for cTnI protein binding. From the XPS result, it shows that each covalent bonding characteristic from APTES deposition until cTnI antibody-antigen interaction. Finally, the electrical (Id-Vbg) result show the ability to detect cTnI protein with concentration of 2.0 μg/μl at -150 μA (Vd= 0). As Vd increases, a tremendous increment of electrical conductivity with larger difference of Id value between each surface functionalization processes can be achieved. At Vd= -5, the electrical conductivity jumped up to -1 mA, more than 500% increase compared to Vd= 0.