ABSTRACT
Photonic crystal hydrogels (PCHs), with smart stimulus-responsive abilities, have been widely exploited as colorimetric sensors for years. However, the current fabrication technologies are mostly applicable to produce PCHs with simple geometries at the sub-millimeter scale, limiting the introduction of structural design into PCH sensors as well as the accompanied advanced applications. This paper reports the microfabrication of three-dimensional (3D) PCHs with the help of supramolecular agarose PCH as a sacrificial scaffold by two-photon lithography (TPL). The supramolecular PCHs, formulated with SiO2 colloidal nanoparticles and agarose aqueous solutions, show bright structural color and are degradable upon short-time dimethyl sulfoxide treatment. Leveraging the supramolecular PCH as a sacrificial scaffold, PCHs with precise 3D geometries can be fabricated in an economical and efficient way. This work demonstrates the application of such a strategy in the creation of structural-designed PCH mechanical microsensors that have not been explored before.
ABSTRACT
In this paper, we experimentally investigate the migration of liquid bridges at the interface of spheres and plates with an imposed thermal gradient. The key influencing factors of interface gap, sphere material and diameter, liquid viscosity, and thermal gradient on the migration behaviors are highlighted. Furthermore, the physical mechanism of this intriguing interfacial phenomenon is numerically unraveled. The originality of this work lies in the fact that when thermal gradients were encountered, liquid bridges could migrate at the interface of spheres and plates, and a general design philosophy of related parameters for enhancing or weakening this thermal flow is proposed.
ABSTRACT
HYPOTHESIS: Thermocapillary migration is a phenomenon that liquid droplets can move from warm to cold regions on a nonuniformly heated surface. We expect to construct functional surfaces to manipulate the migration of liquid lubricants on rubbing surfaces. EXPERIMENTS: Superoleophobic surfaces with wedge shaped superoleophilic grooves of varying geometrical parameters are fabricated, and migration experiments of typical liquid lubricants are performed on the designed surfaces. FINDINGS: Manipulation capacity of the designed surfaces on the migration of liquid lubricants is confirmed, and the mechanism is revealed. An effective method using superoleophobic surfaces with wedge shaped superoleophilic grooves to reconcentrate the migrated lubricants is highlighted. Moreover, a general design philosophy for patterns of wedge shaped groove is proposed.
