@article{BalderasValadezPacholski2021,
  author    = {Balderas-Valadez, Ruth Fabiola and Pacholski, Claudia},
  title     = {Plasmonic Nanohole Arrays on Top of Porous Silicon Sensors},
  series = {ACS applied materials \& interfaces},
  volume    = {13},
  journal   = {ACS applied materials \& interfaces},
  number    = {30},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/acsami.1c07034},
  pages     = {36436 -- 36444},
  year      = {2021},
  abstract  = {Label-free optical sensors are attractive candidates, for example, for detecting toxic substances and monitoring biomolecular interactions. Their performance can be pushed by the design of the sensor through clever material choices and integration of components. In this work, two porous materials, namely, porous silicon and plasmonic nanohole arrays, are combined in order to obtain increased sensitivity and dual-mode sensing capabilities. For this purpose, porous silicon monolayers are prepared by electrochemical etching and plasmonic nanohole arrays are obtained using a bottom-up strategy. Hybrid sensors of these two materials are realized by transferring the plasmonic nanohole array on top of the porous silicon. Reflectance spectra of the hybrid sensors are characterized by a fringe pattern resulting from the Fabry-P{\´e}rot interference at the porous silicon borders, which is overlaid with a broad dip based on surface plasmon resonance in the plasmonic nanohole array. In addition, the hybrid sensor shows a significant higher reflectance in comparison to the porous silicon monolayer. The sensitivities of the hybrid sensor to refractive index changes are separately determined for both components. A significant increase in sensitivity from 213 ± 12 to 386 ± 5 nm/RIU is determined for the transfer of the plasmonic nanohole array sensors from solid glass substrates to porous silicon monolayers. In contrast, the spectral position of the interference pattern of porous silicon monolayers in different media is not affected by the presence of the plasmonic nanohole array. However, the changes in fringe pattern reflectance of the hybrid sensor are increased 3.7-fold after being covered with plasmonic nanohole arrays and could be used for high-sensitivity sensing. Finally, the capability of the hybrid sensor for simultaneous and independent dual-mode sensing is demonstrated.},
  language  = {en}
}
@article{RudolphMohrToetzkeKardjilovetal.2017,
  author    = {Rudolph-Mohr, Nicole and Toetzke, Christian and Kardjilov, Nikolay and Oswald, Sascha Eric},
  title     = {Mapping water, oxygen, and pH dynamics in the rhizosphere of young maize roots},
  series = {Journal of plant nutrition and soil science = Zeitschrift f{\"u}r Pflanzenern{\"a}hrung und Bodenkunde},
  volume    = {180},
  journal   = {Journal of plant nutrition and soil science = Zeitschrift f{\"u}r Pflanzenern{\"a}hrung und Bodenkunde},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1436-8730},
  doi       = {10.1002/jpln.201600120},
  pages     = {336 -- 346},
  year      = {2017},
  abstract  = {Rhizosphere processes are highly dynamic in time and space and strongly depend on each other. Key factors influencing pH changes in the rhizosphere are root exudation, respiration, and nutrient supply, which are influenced by soil water content levels. In this study, we measured the real-time distribution of soil water, pH changes, and oxygen distribution in the rhizosphere of young maize plants using a recently developed imaging approach. Neutron radiography was used to capture the root system and soil water distribution, while fluorescence imaging was employed to map soil pH and soil oxygen changes. Germinated seeds of maize (Zea mays L.) were planted in glass rhizotrons equipped with pH and oxygen-sensitive sensor foils. After 20 d, the rhizotrons were wetted from the bottom and time-lapsed images via fluorescence and neutron imaging were taken during the subsequent day and night cycles for 5 d. We found higher water content and stronger acidification in the first 0.5 mm from the root surface compared to the bulk soil, which could be a consequence of root exudation. While lateral roots only slightly acidified their rhizosphere, crown roots induced stronger acidification of up to 1 pH unit. We observed changing oxygen patterns at different soil moisture conditions and increasing towards lateral as well as crown roots while extending laterally with ongoing water logging. Our work indicates that plants alter the rhizosphere pH and oxygen also depending on root type, which may indirectly arise also from differences in age and water content changes. The results presented here were possible only by combining different imaging techniques to examine profiles at the root-soil interface in a comprehensive way during wetting and drying.},
  language  = {en}
}