Abstract
It is well known that the DNA (Deoxyribonucleic Acid) assays have been used widely in bio-medical tests and in many applications of bio-identification. Because DNA has the specific property, we can use DNA assays to justify if the target DNA exists and how many it is in the samples. Rolling Circle Amplification (RCA) is a novel technology in both quantitative and qualitative DNA assays. Unlike the conventional Polymerase Chain Reaction (PCR) process, the RCA process can be proceeded in the room temperature to amplify a few of target DNAs which are extracted from the samples. Besides, the immobilized RCA can occur on the surface of silicon-based material with the modification of 3-Aminopropyltriethoxysilane (APTES). In this work, we are devoted to real-time detecting the changes of DNA concentrations in the immobilized RCA process with the current CMOS devices. Instead of using the fluorescence-labeling or doing the electrophoresis, a CMOS-compatible Extended-Gate Field Effect Transistor (EGFET) with its native passivation (silicon nitride) is employed to monitor the concentration change of the target DNA in the immobilized RCA process. Besides, the other CMOS-compatible open-gate ISFET is also proposed to do the pilot test of the DNA detection. Finally, three types of readout circuits with embedded EGFETs are proposed to read the surface potential of the embedded EGFETs directly and characterized electrically.