Direct conversion of light into mechanical work, known as the photomechanical effect, is an emerging field of research, largely driven by the development of novel molecular and polymeric material systems. However, the fundamental impediment is that the previously explored materials and structures do not simultaneously offer fast and wavelength-selective response, reversible actuation, low-cost fabrication and large deflection. Here, we demonstrate highly versatile photoactuators, oscillators and motors based on polymer/single-walled carbon nanotube bilayers that meet all the above requirements. By utilizing nanotubes with different chirality distributions, chromatic actuators that are responsive to selected wavelength ranges are achieved. The bilayer structures are further configured as smart 'curtains' and light-driven motors, demonstrating two examples of envisioned applications.

Micro- and nanoscale structures of chitosan were fabricated by nanoimprinting lithography and biochemically functionalized for bionanodevice applications. Chitosan solutions were prepared and a nanoimprinting process was developed for it, where chitosan solution is used as a functional resist for nanoimprinting lithography. A low temperature (90°C) and low pressure (5–25psi) nanoimprinting with polydimethylsiloxane mold could achieve not only microscale structures but also nanoscale features such as nanowire and nanodots down to 150nm dimensions. The nanoimprinted structures were chemically modified and used for the immobilization of protein molecules.

Printable electronics and the increased use of nanoparticle products (e.g. quantum dots) has resulted in the rapid development of nanoparticle inks. Microfl uidic reactors -or microreactors -show promise to provide advanced control over size, size distribution and shape for commercial-scale synthesis of nanoparticles. Compared to batch-wise synthesis techniques primarily in use today, microfl uidic technology can provide better control of the reaction conditions, which is the key to controlling the product characteristics. [ 1 ] Handling small volumes of liquid allows better control of mixing, and hence yields more uniform chemical composition. For thermally activated syntheses, reagents can be heated and cooled rapidly and uniformly, avoiding the large thermal gradients typically found throughout the reaction volume in batch techniques. Several high-temperature microreactors for synthesizing nanoparticles have been described in the literature. [ 2 ] Almost all microreactors described to date have a single heated zone where nucleation and growth of particles as well as reaction processes which should be controlled at different temperatures for proper completion, are executed at the same temperature. In order to obtain monodisperse or near-monodisperse size distributions, the nucleation and growth stages must be separated. [ 3 ] LaMer et al. discussed this concept for the reduction of thiosulphate to sulphur, in terms of the concentration of sulphur monomers. [ 4 ] The rate at which thiosulphate is reduced, and hence the sulphur monomer concentration at a given time, is temperature dependent. The principles elucidated by LaMer are broadly applicable to thermally activated syntheses. Of the few reactors with multiple temperature zones, Yang et al. introduced a capillary-based microreactor. [ 2l ] However due to the lack of thermal isolation between these two zones, it was not possible to quench nucleation. This paper focuses on the design and fabrication of an ideal, functioning Multi-Temperature zone Microreactor (MTM) on a silicon substrate, built upon theoretical concepts introduced by Winterton et al. [ 5 ] As discussed by Winterton et al., the necessary concentration profi les can be controlled by controlling the temperature as a function of time. [ 5 ] Ideally, one needs a very short zone of the reactor at a high temperature, to trigger nucleation, followed by a longer duration at a lower temperature where growth occurs to ensure narrow nanoparticle distributions. However Winterton et al. did not fabricate a microreactor to base their ideas. The MTM is the fi rst fabricated and experimentally tested microreactor in literature that has multiple thermally isolated heated and cooled zones designed to separate nucleation and growth as well as to provide a platform for carrying out a systematic study on the effects of temperature and residence time on nanoparticle formation. In this work, TiO 2 nanoparticles were selected as a model system to demonstrate the functionality of the microreactor.The MTM utilizes t...

A novel microfluidic molding process was used to form microscale features of gold nanoparticles on polyimide, glass, and silicon substrates. This technique uses permeation pumping to pattern and concentrate a nanoparticle ink inside microfluidic channels created in a porous polymer template in contact with a substrate. The nanoparticle ink is self-concentrated in the microchannels, resulting in dense, close-packed nanoparticle features. The method allows for better control over the structure of printed features at a resolution that is comparable to inkjet printing, and is purely additive with no residual layers or etching required. The process uses low temperatures and pressures and takes place in an ambient environment. After patterning, the gold nanoparticles were sintered into continuous and conductive gold traces.