[Show abstract][Hide abstract]ABSTRACT: Reported here is the fabrication of solvent-tunable polydimethylsiloxane (PDMS) microlenses using the femtosecond laser direct writing (FsLDW) technique. PDMS microlenses with equation-defined profiles, including both spherical microlens and aspheric hyperboloid microlens, have been fabricated according to preprogrammed models. In addition to excellent optical performance derived from the high accuracy and smooth surface, the resultant PDMS microlenses also show unique solvent-tunable properties; the focal length could be dynamically tuned by organic solvents of different solubility parameters. To obtain better control over the tunable property, a PDMS microlens has been flexibly integrated with a microfluidic device. Under the stimulation of different solvents, its tunable imaging performance has been demonstrated in a controlled manner.
Full-text · Article · Jan 2014 · Journal of Materials Chemistry C
[Show abstract][Hide abstract]ABSTRACT: Reported in this paper is a solvothermal synthesis of highly porous polydivinylbenzene. The nanoporous structures of the resultant polymers could be modulated from macro/mesoporosity to meso/microporosity by simply changing the amount of acetone solvent in the synthesis. A micro-phase separation during the solvothermal process was found to be the key factor for this transition in porous structures. The hierarchically porous polymers prepared here were characterized by N2 physi-sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and contact angle testing. Experimental results show that these nanoporous polymers have large BET surface areas (up to 420 m2/g), large pore volumes (up to 1.73 cm3/g), and superhydrophobicity due to their highly porous structures, which make these nanoporous materials an excellent candidate for selective removal of toxic volatile organic compounds (VOCs). In the adsorption tests, the nanoporous polymers show outstanding adsorptive capacity and very high selectivity to organic compounds, giving a great potential for indoor VOCs removal.
No preview · Article · Nov 2012 · Colloids and Surfaces A Physicochemical and Engineering Aspects
[Show abstract][Hide abstract]ABSTRACT: Reported here is the design and fabrication of three-dimensional (3D) "overpass" microstructures at the junction of crossed microfluidic channels by femtosecond laser direct writing of photopolymers. The post-integrated overpass could be used for guiding different microfluids across the junction without mixing; therefore it is proposed as an enabler for achieving 3D microfluidic chips based on conventional two-dimensional (2D) microchannels. As representative examples, bi-crossed and tri-crossed microchannels have been equipped with bi-connected and tri-connected overpasses, respectively. Flow tests confirm 3D flowing capability. The integration of such overpass structures at the microchannel junction provides an opportunity to impart 3D capability to conventional 2D microchips, thus the method may hold great promise for both functionalization and miniaturization of Lab-on-a-Chip systems.
[Show abstract][Hide abstract]ABSTRACT: The wonderful world of graphene! A simple one-step fabrication of biomimetic graphene surfaces that possess both superhydrophobicity and bright structural color is presented. By using two-beam laser interference, construction of periodic grating microstructures and removal of hydrophilic oxygen groups were realized at the same time.
Full-text · Article · Feb 2012 · Chemistry - An Asian Journal