Effect of a protective layer on a carbon nanotube thin film channel in a biosensor device

We investigated the effect of HfO2 film on the sensor response of a carbon nanotube thin film transistor (CNT-TFT) biosensor. Some parts of the CNT in the channel are suspended due to the formation of a network structure. The electrical noise of the CNT-TFT as a transducer is mainly caused by the structural fluctuation of the suspended CNTs in solution. We found that the electrical noise is dramatically reduced by introducing hafnium oxide (HfO2) film onto the CNT-TFT channel surface. This means that the HfO2 film has a suppression effect of fluctuation on the suspended CNTs and physical adsorption of the impurities such as non-specific molecules. We demonstrate that introducing HfO2 film is effective for the detection of thrombin molecules using the aptamer-modified CNT-TFT.