@article{NiedlBeta2015,
  author    = {Niedl, Robert Raimund and Beta, Carsten},
  title     = {Hydrogel-driven paper-based microfluidics},
  series = {LAB on a chip : miniaturisation for chemistry and biology},
  volume    = {15},
  journal   = {LAB on a chip : miniaturisation for chemistry and biology},
  number    = {11},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1473-0197},
  doi       = {10.1039/c5lc00276a},
  pages     = {2452 -- 2459},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}
@misc{NiedlBeta2015,
  author    = {Niedl, Robert Raimund and Beta, Carsten},
  title     = {Hydrogel-driven paper-based microfluidics},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-81083},
  pages     = {2452 -- 2459},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}
@article{NiedlBeta2015,
  author    = {Niedl, Robert Raimund and Beta, Carsten},
  title     = {Hydrogel-driven paper-based microfluidics},
  series = {LAB on a chip : miniaturisation for chemistry and biology},
  volume    = {11},
  journal   = {LAB on a chip : miniaturisation for chemistry and biology},
  number    = {15},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1473-0197},
  doi       = {10.1039/c5lc00276a},
  pages     = {2452 -- 2459},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}
@misc{NiedlBerensteinBeta2016,
  author    = {Niedl, Robert Raimund and Berenstein, Igal and Beta, Carsten},
  title     = {How imperfect mixing and differential diffusion accelerate the rate of nonlinear reactions in microfluidic channels},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95810},
  pages     = {6451 -- 6457},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{NiedlBerensteinBeta2016,
  author    = {Niedl, Robert Raimund and Berenstein, Igal and Beta, Carsten},
  title     = {How imperfect mixing and differential diffusion accelerate the rate of nonlinear reactions in microfluidic channels},
  series = {Physical chemistry, chemical physics : PCCP ; a journal of European Chemical Societies},
  volume    = {18},
  journal   = {Physical chemistry, chemical physics : PCCP ; a journal of European Chemical Societies},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1463-9076},
  doi       = {10.1039/c6cp00224b},
  pages     = {6451 -- 6457},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Niedl2015,
  author    = {Niedl, Robert Raimund},
  title     = {Nichtlineare Kinetik und responsive Hydrogele f{\"u}r papierbasierte Schnelltestanwendungen},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-77735},
  school      = {Universit{\"a}t Potsdam},
  pages     = {iv, 128},
  year      = {2015},
  abstract  = {Viele klinische Schnelltestsysteme ben{\"o}tigen vorpr{\"a}parierte oder aufgereinigte Analyte mit frisch hergestellten L{\"o}sungen. Fernab standardisierter Laborbedingungen wie z.B. in Entwicklungsl{\"a}ndern oder Krisengebieten sind solche Voraussetzungen oft nur unter einem hohen Aufwand herstellbar. Zus{\"a}tzlich stellt die erforderliche Sensitivit{\"a}t die Entwicklung einfach zu handhabender Testsysteme vor große Herausforderungen. Autokatalytische Reaktionen, die sich mit Hilfe sehr geringer Initiatorkonzentrationen ausl{\"o}sen lassen, k{\"o}nnen hier eine Perspektive f{\"u}r Signalverst{\"a}rkungsprozesse bieten. Aus diesem Grund wird im ersten Teil der vorliegenden Arbeit das Verhalten der autokatalytischen Arsenit-Jodat-Reaktion in einem mikrofluidischen Kanal untersucht. Dabei werden insbesondere die diffusiven und konvektiven Einfl{\"u}sse auf die Reaktionskinetik im Vergleich zu makroskopischen Volumenmengen betrachtet. Im zweiten Teil werden thermoresponsive Hydrogele mit einem kanalstrukturierten Papiernetzwerk zu einem neuartigen, kapillargetriebenen, extern steuerbaren Mikrofluidik-System kombiniert. Das hier vorgestellte Konzept durch Hydrogele ein papierbasiertes LOC-System zu steuern, erm{\"o}glicht zuk{\"u}nftig die Herstellung von komplexeren, steuerbaren Point-Of-Care Testsystemen (POCT). Durch z.B. einen thermischen Stimulus, wird das L{\"o}sungsverhalten eines Hydrogels so ver{\"a}ndert, dass die gespeicherte Fl{\"u}ssigkeit freigesetzt und durch die Kapillarkraft des Papierkanals ins System transportiert wird. Die Eigenschaften dieses Gelnetzwerks k{\"o}nnen dabei so eingestellt werden, dass eine Freisetzung von Fl{\"u}ssigkeiten sogar bei K{\"o}rpertemperatur m{\"o}glich w{\"a}re und damit eine Anwendung g{\"a}nzlich ohne weitere Hilfsmittel denkbar ist. F{\"u}r die Anwendung notwendige Chemikalien oder Enzyme lassen sich hierbei bequem in getrocknetem Zustand im Papiersubstrat vorlagern und bei Bedarf in L{\"o}sung bringen. Im abschließenden dritten Teil der Arbeit wird ein durch Hydrogele betriebener, Antik{\"o}rper-basierter Mikroorganismenschnelltest f{\"u}r Escherichia coli pr{\"a}sentiert. Dar{\"u}ber hinaus wird weiterf{\"u}hrend eine einfache Methode zur Funktionalisierung eines Hydrogels mit Biomolek{\"u}len {\"u}ber EDC/NHS-Kopplung vorgestellt.},
  language  = {de}
}
@article{HeinsohnNiedlAnielskietal.2022,
  author    = {Heinsohn, Natascha Katharina and Niedl, Robert Raimund and Anielski, Alexander and Lisdat, Fred and Beta, Carsten},
  title     = {Electrophoretic mu PAD for purification and analysis of DNA samples},
  series = {Biosensors : open access journal},
  volume    = {12},
  journal   = {Biosensors : open access journal},
  number    = {2},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2079-6374},
  doi       = {10.3390/bios12020062},
  pages     = {15},
  year      = {2022},
  abstract  = {In this work, the fabrication and characterization of a simple, inexpensive, and effective microfluidic paper analytic device (mu PAD) for monitoring DNA samples is reported. The glass microfiber-based chip has been fabricated by a new wax-based transfer-printing technique and an electrode printing process. It is capable of moving DNA effectively in a time-dependent fashion. The nucleic acid sample is not damaged by this process and is accumulated in front of the anode, but not directly on the electrode. Thus, further DNA processing is feasible. The system allows the DNA to be purified by separating it from other components in sample mixtures such as proteins. Furthermore, it is demonstrated that DNA can be moved through several layers of the glass fiber material. This proof of concept will provide the basis for the development of rapid test systems, e.g., for the detection of pathogens in water samples.},
  language  = {en}
}