@article{WintzheimerOppmannDoldetal.2019,
  author    = {Wintzheimer, Susanne and Oppmann, Maximilian and Dold, Martin and Pannek, Carolin and Bauersfeld, Marie-Luise and Henfling, Michael and Trupp, Sabine and Schug, Benedikt and Mandel, Karl},
  title     = {Indicator Supraparticles for Smart Gasochromic Sensor Surfaces Reacting Ultrafast and Highly Sensitive},
  series = {Particle \& Particle Systems Characterization},
  volume    = {36},
  journal   = {Particle \& Particle Systems Characterization},
  number    = {10},
  doi       = {10.1002/ppsc.201900254},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213671},
  year      = {2019},
  abstract  = {The detection of toxic gases, such as NH\(_{3}\) and CO, in the environment is of high interest in chemical, electronic, and automotive industry as even small amounts can display a health risk for workers. Sensors for the real-time monitoring of these gases should be simple, robust, reversible, highly sensitive, inexpensive and show a fast response. The indicator supraparticles presented herein can fulfill all of these requirements. They consist of silica nanoparticles, which are assembled to supraparticles upon spray-drying. Sensing molecules such as Reichardt's dye and a binuclear rhodium complex are loaded onto the microparticles to target NH\(_{3}\) and CO detection, respectively. The spray-drying technique affords high flexibility in primary nanoparticle size selection and thus, easy adjustment of the porosity and specific surface area of the obtained micrometer-sized supraparticles. This ultimately enables the fine-tuning of the sensor sensitivity and response. For the application of the indicator supraparticles in a gas detection device, they can be immobilized on a coating. Due to their microscale size, they are large enough to poke out of thin coating layers, thus guaranteeing their gas accessibility, while being small enough to be applicable to flexible substrates.},
  language  = {en}
}
@article{MillerWintzheimerPrieschletal.2021,
  author    = {Miller, Franziska and Wintzheimer, Susanne and Prieschl, Johannes and Strauss, Volker and Mandel, Karl},
  title     = {A Supraparticle-Based Five-Level-Identification Tag That Switches Information Upon Readout},
  series = {Advanced Optical Materials},
  volume    = {9},
  journal   = {Advanced Optical Materials},
  number    = {4},
  doi       = {10.1002/adom.202001972},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224469},
  year      = {2021},
  abstract  = {Product identification tags are of great importance in a globalized world with increasingly complex trading routes and networks. Beyond currently used coding strategies, such as QR codes, higher data density, flexible application as well as miniaturization and readout indication are longed for in the next generation of security tags. In this work, micron-sized supraparticles (SPs) with encoded information (ID) are produced that not only exhibit multiple initially covert identification levels but are also irreversibly marked as "read" upon readout. To achieve this, lanthanide doped CaF\(_{2}\) nanoparticles are assembled in various quantity-weighted ratios via spray-drying in presence of a broad-spectrum stealth fluorophore (StFl), yielding covert spectrally encoded ID-SPs. Using these as pigments, QR codes, initially dominated by the green fluorescence of the StFl, could be generated. Upon thermal energy input, these particle-based tags irreversibly switch to an activated state revealing not only multiple luminescent colors but also spectral IDs. This strategy provides the next generation of material-based security tags with a high data density and security level that switch information upon readout and can be, therefore, used as seal of quality.},
  language  = {en}
}