The application of molecular switches
for the fabrication of multistimuli-responsive
chromic materials and devices still remains a challenge because of
the restrictions imposed by the supporting solid matrices where these
compounds must be incorporated: they often critically affect the chromic
response as well as limit the type and nature of external stimuli
that can be applied. In this work, we propose the use of ionogels
to overcome these constraints, as they provide a soft, fluidic, transparent,
thermally stable, and ionic-conductive environment where molecular
switches preserve their solution-like properties and can be exposed
to a number of different stimuli. By exploiting this strategy, we
herein pioneer the preparation of nitrospiropyran-based materials
using a single solid platform that exhibit optimal photo-, halo-,
thermo-, and electrochromic switching behaviors.
The
fast and simple fabrication of modular microfluidic devices comprising
different fluidic components and configurations that can rapidly be
assembled and reconfigured depending on the requirements of a particular
application is very attractive. The application of these modular systems
as complete analysis systems requires the incorporation of flow-cell
modules capable of selectively detecting chemical species. Here, a
new magnetic clamping approach is presented that allows both interconnection
of microfluidic modules and reversible integration of solid-state
sensors. Planar and optically transparent materials are used to easily
assess device fluidic performance. Double-sided polyacrylic adhesive
layers, sandwiched between two transparent polycarbonate films, are
mechanized to produce fluidic structures containing the required inlets
and outlets. The latter also include chemically bonded poly(dimethylsiloxane)
gaskets for easy leak-free interconnection of the different modules
and the incorporation of chemical sensors without adding dead volumes.
Microfluidic channels, junctions, mixers and flow cells with solid-stated
sensors are thus fabricated. Different microfluidic modules are assembled
with the aid of poly(methyl methacrylate) clamping structures containing
embedded magnets. By using a magnetic breadboard, complete microfluidic
analysis systems can be arranged in a few minutes. Three systems incorporating
conductivity, amperometric, or pH sensors are thus assembled and fully
characterized to show the advantages of the presented approach for
analytical applications.
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