A nanoscale actuator or an array of such actuators can be used for many potential applications. For example, to investigate the effect of an external force on a cell (transfer of inter-cell signaling, and change of cell function), one must know how to generate and control the required force. In a recent study performed at the Stevens Institute of Technology, which was published in Nanotechnology, the authors used individual multiwall nanotubes (MWNTs) to create bimorph nanoactuators that generate the microNewton force.

The deflection and force generated at the tip of the bimorph nanoactuator are originated from the mismatch of coefficient of thermal expansion (CTE) between two constituting layered materials. To create such nanoscale bimorph structures, the researchers used a directional deposition method called pulsed laser deposition (PLD) technique to enable the deposition of a metal film on only one side of a MWNT exposing the other side as a bare MWNT surface. They measured the force from the nanoactuator by sweeping an AFM tip laterally at the middle of a bimorph.

The thermally generated force twisted the AFM cantilever further, and this amount appeared as an increase as the temperature was elevated by a thermal stage under the AFM. A vertical array of such bimorph nanoactuators can be fabricated using various sets of materials, if necessary, to elucidate the mechanochemical response of individual biological cell.