Design and Characterization of a Passive Wireless DNA Sensor

This research is aiming at developing an innovative DNA sensing platform that exploits a multidisciplinary area synthesizing the conventional DNA capacitive sensing mechanism and surface-based conformational characterization throughout DNA immobilization and hybridization. The resonant frequency shift caused by the change of capacitance throughout DNA immobilization and hybridization occurring on top of a capacitor is monitored by the means of impedance analyzer, with which it is possible to inspect the graph amplitude on the behavior of signal strength and compute the quality factor of the coupling element represented by bandwidth. Experiments for measuring the frequency shift due to interface charge transmission were carried out to study its DNA sensing mechanism and the possibility of DNA sensing enhancement. 32 samples were measured throughout the experiment and the average capacitance measurements represented a variety of surface charges resulting from DNA molecule behavior. It is found that the capacitance changed from 11.58pF to 114.5pF when specific ssDNA was attached to electrodes and then increased to 218.6pF once complementary strand DNA was involved and hybridized with existing DNA chains. In addition, using impedance analyzer measurements, the resonant frequency decreased from 2.01MHz to 1.97MHz in the presence of ssDNA and further down to 0.95MHz after the complementary strand DNA was deposited.