Estrela et al. employed MOS capacitors consisting of Au/SiO2/Si and Poly-Si TFTs with a gold metal gate as ISFET biosensor for label-free electrical detection of DNA hybridization [31]. When probe DNA bind to its complementary DNA, changes in electric potential in the electric double layer occur, leading to a shift in the C–V (capacitance–voltage) or I–V (current-voltage) characteristics.