Aligned carbon nanotubes on quartz substrate for liquid gated biosensing

A facile and high performance biosensing platform using aligned carbon nanotubes on quartz substrate is reported in this communication. Single walled carbon nanotubes are grown on quartz substrates by a chemical vapor deposition process and are characterized with field emission scanning electron microscopy and atomic force microscopy in order to verify the quality of the material. The quartz substrate is then directly used as a biosensor in a field effect transistor configuration. In order to demonstrate the sensing capabilities of the fabricated sensor devices, electronic detection of prostate specific antigen, a potential cancer biomarker, is carried out by adopting liquid gated configuration. A conductivity change due to the specific binding of target antigen with the immobilized receptor antibody demonstrates the sensing capabilities of the fabricated device. Sub-nM detection sensitivities have been obtained using the adopted direct immunoassay approach, which shows that the device responds to clinically relevant concentration regimes.