We developed a method to collect micro- and nano-vesicles on a glass substrate using the optical pressure of a laser beam. The laser beam was focused on the glass substrate which sandwiches a suspension containing micro- or nano-sized vesicles prepared by a phospholipid. The optical pressure generated at the interface of the medium and the vesicles accelerated the vesicles to form aggregates on the glass surface. Two types of glass substrates, hydrophilic and aminated ones, showed no difference in the adsorption property of the vesicles. Time to be required for collecting a certain amount of the vesicles was inversely proportional to the concentration of the vesicles. To enhance the collection efficiency, gold nanoparticles were added to the suspension of the vesicles. We found that gold nanoparticles reduced the collection time as short as 1/10-times.
We report on selective metal deposition over complex polymer structures formed by two-photon induced photopolymerization
(TPP) technique. Periodic three-dimensional (3D) polymer micro/nanostructures are fabricated
by means of a microlens array to produce multiple spots from a single-beam femtosecond laser amplified
by a regenerative amplifier. The photopolymerizable resin and the glass substrate are chemically modified, and a
pre-treatment with SnCl2 is applied before realizing a uniform silver coating by electroless plating. This preparation
enables a selective deposition of small silver particles only on the polymer surface all over the sample and
to avoid metal deposition on the substrate. Electrical measurements show the structures to be highly conductive
with typical resistivities ρ approx. 10-7 Ωm, only a few times larger than the value for bulk silver. By taking advantage
of the high accuracy and arbitrary shape modeling of TPP fabrication, we can realize complex periodic and/or
metallic micro-nanostructures which were so far out of reach. Thus, a straightforward application could be the
realization of metamaterials. The processing efficiency of our technique is demonstrated with the fabrication of
several large samples, created by more than 700 objects written in parallel and metallized with silver.
Recently, fabrication of metal micro-pattern has attracted a great attention. For such purpose, site-selective activation is crucial for metal deposition on a substrate, and it can be achieved through lithography, chemical vapor deposition and micro-contact printing. Here, we propose to control the activation point three-dimensionally (3D) through two-photon absorption (TPA) polymerization method, which leads to 3D site-selective deposition. Two types of photopolymer were prepared for deposition control of metal through electroless plating method. One was a commercially available resin, which is typically inactive to metal deposition. Another was a modified resin containing suitable functional groups for metal adhesion. We created a 3D polymer structure consisting of those two components by localizing each resin through TPA method. The fabricated structures were immersed in an electroless plating solution of silver. The partially silver coated sample was observed by a scanning electron microscope after washing and desiccation. Metal microstructure supported with polymer can be realized by 3D site-selective metal deposition. Therefore, it is a useful technique for 3D aligned metallic microstructures without any contacts each other.
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