TY  - JOUR
A1  - Niedl, Robert Raimund
A1  - Beta, Carsten
T1  - Hydrogel-driven paper-based microfluidics
JF  - LAB on a chip : miniaturisation for chemistry and biology
N2  - Paper-based microfluidics provide an inexpensive, easy to use technology for point-of-care diagnostics in developing countries. Here, we combine paper-based microfluidic devices with responsive hydrogels to add an entire new class of functions to these versatile low-cost fluidic systems. The hydrogels serve as fluid reservoirs. In response to an external stimulus, e.g. an increase in temperature, the hydrogels collapse and release fluid into the structured paper substrate. In this way, chemicals that are either stored on the paper substrate or inside the hydrogel pads can be dissolved, premixed, and brought to reaction to fulfill specific analytic tasks. We demonstrate that multi-step sequences of chemical reactions can be implemented in a paper-based system and operated without the need for external precision pumps. We exemplify this technology by integrating an antibody-based E. coli test on a small and easy to use paper device.
Y1  - 2015
U6  - https://doi.org/10.1039/c5lc00276a
SN  - 1473-0197
SN  - 1473-0189
VL  - 11
IS  - 15
SP  - 2452
EP  - 2459
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Niedl, Robert Raimund
A1  - Berenstein, Igal
A1  - Beta, Carsten
T1  - How imperfect mixing and differential diffusion accelerate the rate of nonlinear reactions in microfluidic channels
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European Chemical Societies
N2  - In this paper, we show experimentally that inside a microfluidic device, where the reactants are segregated, the reaction rate of an autocatalytic clock reaction is accelerated in comparison to the case where all the reactants are well mixed. We also find that, when mixing is enhanced inside the microfluidic device by introducing obstacles into the flow, the clock reaction becomes slower in comparison to the device where mixing is less efficient. Based on numerical simulations, we show that this effect can be explained by the interplay of nonlinear reaction kinetics (cubic autocatalysis) and differential diffusion, where the autocatalytic species diffuses slower than the substrate.
KW  - arsenious acid
KW  - systems
KW  - poly(dimethylsiloxane)
KW  - fronts
KW  - scale
KW  - paper
Y1  - 2016
U6  - https://doi.org/10.1039/c6cp00224b
SN  - 1463-9076
SN  - 1463-9084
VL  - 18
SP  - 6451
EP  - 6457
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -