Photoactuated Pens for Molecular Printing.

The photoactuation of pen arrays made of polydimethylsiloxane carbon nanotube composites is explored, and the first demonstration of photoactuated pens for molecular printing is reported. Photoactuation of these composites is characterized using atomic force microscopy and found to produce microscale motion in response to modest illumination, with an actuation efficiency as high as 200 nm mW on the sub-1 s time scale. Arrays of composite pens are synthesized and it is found that local illumination is capable of moving selected pens by more than 3 µm out of the plane, bringing them into contact to perform controllable and high quality printing while completely shutting off the nonilluminated counterparts. In light of the scalability limitations of nanolithography, this work presents an important step and paves the way for arbitrary control of individual pens in massive arrays. As an example of a scalable soft actuator, this approach can also aid progress in other fields such as soft robotics and microfluidics.