Investigation of DNA Detection Mechanism with AlGaN/GaN High Electron Mobility Transistor (HEMT) Biosensor in High Ionic Strength Solution

Abstract

In this research, the electrical double layer HEMT device is used to serve as the cardiovascular disease (CVD) RNA biomarkers biosensor. In this experiment, we try to use the DNA equivalent to miRNA-126 to test the ability of the novel DNA sensors. Short Debye length has been a haunted problem among all the field effect transistor (FET) biosensor for years. As the Debye length is extremely short in high ionic strength solutions, the traditional FET may not be directly detecting the biomolecule. The novel HEMT sensors using AlGaN/GaN can perform high sensitivity and great specificity in DNA sequences testing. The detection limit can be down to the 1fM and the specificity measurement can identify the signals between two DNA sequences with six-base mismatch. Furthermore, the mechanism of the sensor structure has also been studied. Since the structure of the device has the separation between source drain channel and gate electrode, the comparison with different electrode area and gap distance has been done as well. With repeating electrical measurement confirming, the reusability can also be seen after the 95℃ dehybridization process. With the Gibbs free energy ∆G of the specific sequences, we can also predict the equilibrium reaction constant and the binding ratio of probe DNA with the target DNA. The comparison between the thermal dynamics with the experiment consequence has been demonstrated too.