We have grown tree-like vertically-aligned carbon nanotubes (CNTs) on silicon substrate, suitable for highly sensitive interdigital capacitive sensors. As an application, we present a sensitive pressure sensor with branched CNTs as its capacitance plates.
After realization of the interdigital structure, the growth of CNTs has been achieved through direct-current plasma enhanced chemical vapor deposition (DC-PECVD) method. A sequential growth and hydrogenation has led to the formation of multiple branched structures of nanotubes. The growth of tree-like CNTs on the interdigitally patterned substrate results in a high overlap between adjacent fingers and consequently a significant response to mechanical variations of the membrane as a result of the applied pressure.