We report the first fluorescence light detector combining a fully solution processed organic electrochemical cell (OLEC) and a fully solution processed organic photodiode (OPD) within one microfluidic chip. The blue OLEC was used as the excitation source, whereas the OPD was used for detection of the emitted fluorescent light. Two orthogonally oriented linear polarizers were used as excitation and emission filters, enabling the use of fluorescent dyes with emission and absorption peaks very close to each other. In addition the system is compatible with many different fluorescent dyes. The filters and organic devices were mounted onto a microfluidic glass chip. Fluorescein amidite (FAM) was used as a model dye to characterize and demonstrate the concept of the system. Despite a very close excitation peak (492 nm) and emission peak (518 nm) of FAM, we were able to detect FAM concentrations as low as 1 μM even for a brightness value of the OLEC as low as 500 cd m -2. This opens the possibility of producing low cost, portable and disposable fluorescence sensors with a high sensitivity
A strength of microfluidic chip laboratories is the rapid heat transfer that, in principle, enables a very homogeneous temperature distribution in chemical processes. In order to exploit this potential, we present an integrated chip system where the temperature is precisely controlled and monitored at the microfluidic channel level. This is realized by integration of a luminescent temperature sensor layer into the fluidic structure together with inkjet-printed micro heating elements. This allows steering of the temperature at the microchannel level and monitoring of the reaction progress simultaneously. A fabrication procedure is presented that allows for straightforward integration of thin polymer layers with optical sensing functionality in microchannels of glass-polydimethylsiloxane (PDMS) chips of only 150 μm width and 29 μm height. Sensor layers consisting of polyacrylonitrile and a temperature-sensitive ruthenium tris-phenanthroline probe with film thicknesses of about 0.5 to 6 μm were generated by combining blade coating and abrasion techniques. Optimal coating procedures were developed and evaluated. The chip-integrated sensor layers were calibrated and investigated with respect to stability, reproducibility, and response times. These microchips allowed observation of temperature in a wide range with a signal change of around 1.6 % per K and a maximum resolution of around 0.07 K. The device is employed to study temperature-controlled continuous micro flow reactions. This is demonstrated exemplarily for the tryptic cleavage of coumarin-modified peptides via fluorescence detection.
The functionalized hyper-cross-linked
polymers (HCLPs) with high
Brunauer–Emmett–Teller (BET) surface area (S
BET) were promising porous materials while their facile
fabrication remains a challenge. Herein, a universal strategy was
developed for chloromethylated polystyrene (CMPS) according to the
nucleophilic substitution and Friedel–Crafts alkylation, and
a series of O-enriched HCLPs was fabricated accordingly. The nucleophilic
substitution offered plentiful oxygen to the polymers, and the Friedel–Crafts
alkylation provided the polymers with hyper-cross-linking frameworks
with a unique hierarchical porosity. The resulting polymers had high S
BET’s up to 601 m2/g and abundant
oxygen (up to 13.04 wt %). They exhibited promising adsorption properties
for aniline from aqueous solution with a maximum capacity (q
max) of 223.7 mg/g. In particular, the unique
hierarchical porosity of the polymers endowed the fast diffusion of
aniline in the kinetic adsorption. This universal synthetic protocol
is of great importance for the fabrication of some other functionalized
HCLPs.
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