@article{LeiterWohlschlaegerVersenetal.2022, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian}, title = {An algorithmic method for the identification of wood species and the classification of post-consumer wood using fluorescence lifetime imaging microscopy}, series = {Journal of Sensors and Sensor Systems}, volume = {11}, journal = {Journal of Sensors and Sensor Systems}, number = {1}, doi = {10.5194/jsss-11-129-2022}, pages = {129 -- 136}, year = {2022}, abstract = {In this contribution the frequency domain fluorescence lifetime imaging microscopy (FD-FLIM) technique is evaluated for post-consumer wood sorting. The fluorescence characteristics of several wood samples were determined, whereby two excitation wavelengths (405 and 488 nm) were used. The measured data were processed using algorithmic methods to identify the wood species and post-consumer wood category. With the excitation wavelength of 405 nm, 16 out of 19 samples could be correctly assigned to the corresponding post-consumer wood category by means of the fluorescence lifetimes. Thus, the experimental results revealed the high potential of the FD-FLIM technique for automated post-consumer wood sorting.}, language = {en} } @inproceedings{WohlschlaegerVersenLaforsch2022, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian}, title = {Optical identification of car tire particles on soil using fluorescence lifetime imaging microscopy}, series = {Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES), Technical Digest Series (Optica Publishing Group, 2022)}, booktitle = {Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES), Technical Digest Series (Optica Publishing Group, 2022)}, doi = {10.1364/ES.2022.ETu3H.3}, pages = {ETu3H.3}, year = {2022}, abstract = {Tire wear is one of the major contributors of environmental pollution by microplastic. FD-FLIM in combination with an image processing algorithm are successfully applied to detect tyre wear on soil.}, language = {en} } @article{LeiterWohlschlaegerVersen2023, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Analysis of the phase-dependent fluorescence decay time of treated wood using FD-FLIM}, series = {tm - Technisches Messen}, volume = {90}, journal = {tm - Technisches Messen}, number = {6}, doi = {10.1515/teme-2022-0114}, pages = {401 -- 406}, year = {2023}, abstract = {For sustainable handling of wood and high material utilization, post-consumer wood has to be sorted by post-consumer wood categories in Germany. The non-destructive FD-FLIM method could improve the wood recycling process by automatic classification of waste wood into post-consumer wood classes. Thus, the phase-dependent fluorescence decay time of treated wood is analysed in this study to obtain the impact of the treatment on the fluorescence decay time. It is shown that treated and untreated wood can be differentiated using the fluorescence decay time, although the state-of-the-art theoretical fluorescence decay time differs from the experimentally determined fluorescence decay time.}, language = {en} } @inproceedings{WohlschlaegerHolstVersenetal.2021, author = {Wohlschl{\"a}ger, Maximilian and Holst, Gerhard and Versen, Martin and Laforsch, Christian}, title = {An optical method to differentiate wood from polymers using fluorescence lifetime imaging microscopy}, series = {OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES) (2021), paper EW4G.6}, booktitle = {OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES) (2021), paper EW4G.6}, doi = {10.1364/ES.2021.EW4G.6}, pages = {EW4G.6}, year = {2021}, abstract = {In this contribution investigations with fluorescence lifetime imaging microscopy (FLIM) are made to optically distinguish polymers and wood. The results show that the distinction and identification is possible in a graphical and calculative way.}, language = {en} } @inproceedings{LeiterWohlschlaegerAueretal.2021, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Auer, Veronika and Versen, Martin and Laforsch, Christian}, title = {An algorithmic method to identify multiple wood species in a single image by their specific fluorescence lifetimes}, series = {OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP) (2021), paper CF2B.3}, booktitle = {OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP) (2021), paper CF2B.3}, doi = {10.1364/COSI.2021.CF2B.3}, pages = {CF2B.3}, year = {2021}, abstract = {Fluorescence lifetime imaging microscopy (FLIM) combined with an image processing algorithm is successfully used for the optical identification and areal separation of three wood species of maple, larch and nut in a single taken image.}, language = {en} } @inproceedings{WohlschlaegerKhanLeiteretal.2023, author = {Wohlschl{\"a}ger, Maximilian and Khan, Yamna and Leiter, Nina and Versen, Martin and L{\"o}der, Martin and Laforsch, Christian}, title = {Combining BLOB-Detection and MLP to Detect and Identify Plastics in an Environmental Matrix}, series = {2023 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2023 IEEE Sensors Applications Symposium (SAS)}, doi = {10.1109/SAS58821.2023.10254171}, pages = {1 -- 5}, year = {2023}, abstract = {Environmental pollution by plastics is an increasing problem. However, state-of-the-art methods have significant disadvantages in detecting and identifying plastics directly in an environmental matrix. In this study, we propose a blob detection algorithm in combination with a neural network for fast and automated identification of plastics and non-plastics in a single fluorescence lifetime image. Therefore an artificial environmental matrix is prepared that contains soil, grass, spruce and HDPE (high density polyethylene) particles. Several FD-FLIM (frequency domain fluorescence lifetime imaging microscopy) images are taken, and the detection algorithm and the neural network are applied. We successfully demonstrated the suitability of the thresholding algorithm and the binary classification of the HDPE particles directly in the environmental matrix.}, language = {en} } @article{ManiyattuGeegyWohlschlaegeretal.2023, author = {Maniyattu, Georgekutty Jose and Geegy, Eldho and Wohlschl{\"a}ger, Maximilian and Leiter, Nina and Versen, Martin and Laforsch, Christian}, title = {Multilayer Perceptron Development to Identify Plastics Using Fluorescence Lifetime Imaging Microscopy}, series = {EDFA Technical Articles}, volume = {25}, journal = {EDFA Technical Articles}, number = {3}, doi = {10.31399/asm.edfa.2023-3.p031}, pages = {31 -- 37}, year = {2023}, abstract = {Existing plastic analysis techniques such as Fourier transform infrared spectroscopy and Raman spectroscopy are problematic because samples must be anhydrous and identification can be hindered by additives. This article describes a new approach that has been successfully demonstrated in which plastics can be classified by neural networks that are trained, validated, and tested by frequency domain fluorescence lifetime imaging microscopy measurements.}, language = {en} } @inproceedings{SchwarzWohlschlaegerLeiteretal.2023, author = {Schwarz, Jonas and Wohlschl{\"a}ger, Maximilian and Leiter, Nina and Auer, Veronika and Risse, Michael and Versen, Martin}, title = {Frequency Domain Fluorescence Lifetime Imaging Microscopy (FD-FLIM) analysis of Quercus robur samples for origin differentiation purposes}, series = {Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES)}, booktitle = {Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES)}, doi = {10.1364/AIS.2023.JTu4A.10}, year = {2023}, abstract = {Increasing demand for wood products requires methods to determine its harvest origin and ensure sustainable and legal sourcing. In 15 out of 21 cases, the origin of Quercus robur was differentiable in FD-FLIM studies.}, language = {en} } @article{WohlschlaegerVersenLoederetal.2024, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and L{\"o}der, Martin G. J. and Laforsch, Christian}, title = {Identification of different plastic types and natural materials from terrestrial environments using fluorescence lifetime imaging microscopy.}, series = {Analytical and Bioanalytical Chemistry}, journal = {Analytical and Bioanalytical Chemistry}, doi = {10.1007/s00216-024-05305-w}, year = {2024}, abstract = {Environmental pollution by plastics is a global issue of increasing concern. However, microplastic analysis in complex environmental matrices, such as soil samples, remains an analytical challenge. Destructive mass-based methods for microplastic analysis do not determine plastics' shape and size, which are essential parameters for reliable ecological risk assessment. By contrast, nondestructive particle-based methods produce such data but require elaborate, time-consuming sample preparation. Thus, time-efficient and reliable methods for microplastic analysis are needed. The present study explored the potential of frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) for rapidly and reliably identifying as well as differentiating plastics and natural materials from terrestrial environments. We investigated the fluorescence spectra of ten natural materials from terrestrial environments, tire wear particles, and eleven different transparent plastic granulates <5 mm to determine the optimal excitation wavelength for identification and differentiation via FD-FLIM under laboratory conditions. Our comparison of different excitation wavelengths showed that 445 nm excitation exhibited the highest fluorescence intensities. 445 nm excitation was also superior for identifying plastic types and distinguishing them from natural materials from terrestrial environments with a high probability using FD-FLIM. We could demonstrate that FD-FLIM analysis has the potential to contribute to a streamlined and time-efficient direct analysis of microplastic contamination. However, further investigations on size-, shape-, color-, and material-type detection limitations are necessary to evaluate if the direct identification of terrestrial environmental samples of relatively low complexity, such as a surface inspection soil, is possible.}, language = {en} } @article{WohlschlaegerVersenLoederetal.2024, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and L{\"o}der, Martin G. J. and Laforsch, Christian}, title = {A promising method for fast identification of microplastic particles in environmental samples: A pilot study using fluorescence lifetime imaging microscopy}, series = {Heliyon}, volume = {10}, journal = {Heliyon}, number = {3}, doi = {10.1016/j.heliyon.2024.e25133}, year = {2024}, abstract = {Microplastic pollution of the environment has been extensively studied, with recent studies focusing on the prevalence of microplastics in the environment and their effects on various organisms. Identification methods that simplify the extraction and analysis process to the point where the extraction can be omitted are being investigated, thus enabling the direct identification of microplastic particles. Currently, microplastic samples from environmental matrices can only be identified using time-consuming extraction, sample processing, and analytical methods. Various spectroscopic methods are currently employed, such as micro Fourier-transform infrared, attenuated total reflectance, and micro Raman spectroscopy. However, microplastics in environmental matrices cannot be directly identified using these spectroscopic methods. Investigations using frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) to identify and differentiate plastics from environmental materials have yielded promising results for directly identifying microplastics in an environmental matrix. Herein, two artificially prepared environmental matrices that included natural soil, grass, wood, and high-density polyethylene were investigated using FD-FLIM. Our first results showed that we successfully identified one plastic type in the two artificially prepared matrices using FD-FLIM. However, further research must be conducted to improve the FD-FLIM method and explore its limitations for directly identifying microplastics in environmental samples.}, language = {en} } @inproceedings{WohlschlaegerKhanLeiteretal.2023, author = {Wohlschl{\"a}ger, Maximilian and Khan, Yamna and Leiter, Nina and Versen, Martin and L{\"o}der, Martin and Laforsch, Christian}, title = {Development of a BLOB-detection algorithm based on DoG to detect Plastic in an environmental matrix using FD-FLIM}, series = {Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES)}, booktitle = {Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES)}, doi = {10.1364/ES.2023.EW4E.4}, year = {2023}, abstract = {The direct identification of plastics in an environmental matrix is heavily researched. We successfully developed a BLOB-detection algorithm based on differences of Gaussians to identify HDPE particles in an artificial environmental matrix using FD-FLIM.}, language = {en} } @inproceedings{BernoeckerLeiterWohlschlaegeretal.2022, author = {Bern{\"o}cker, Anton and Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Entwicklung eines neuronalen Netzwerks als Basis zur automatisierten Holzartenerkennung}, series = {18. AALE-Konferenz. Pforzheim, 09.03.-11.03.2022}, booktitle = {18. AALE-Konferenz. Pforzheim, 09.03.-11.03.2022}, organization = {Hochschule f{\"u}r Technik, Wirtschaft und Kultur Leipzig}, doi = {10.33968/2022.11}, year = {2022}, abstract = {Holz ist ein vielseitig einsetzbarer nachwachsender Rohstoff. Neben seinem wirtschaftlichen Nutzen ist er f{\"u}r den Erhalt des Klimas unersetzlich. Eine sortenreine Sortierung f{\"u}r die Weiterverarbeitung von Altholz spielt f{\"u}r einen ressourcenschonenden Umgang eine wichtige Rolle. Um das Potenzial eines neuronalen Netzwerks basierend auf Messdaten der bildgebenden Fluoreszenzabklingzeitmessung f{\"u}r die Altholzsortierung aufzuzeigen, wurden zwei unterschiedliche Klassifikationsans{\"a}tze auf Basis der Programmiersprache Python gew{\"a}hlt. Die Ergebnisse zeigen, dass die bildbasierte Klassifizierung der Holzart mit einer Genauigkeit von 47,36 \% noch ausbauf{\"a}hig ist. Eine datenbasierte Klassifizierung der Holzart mit einer Identifikationsgenauigkeit von 98,28 \% ist dagegen vielversprechend.}, language = {de} } @inproceedings{LeiterWohlschlaegerVersen2022, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Frequency-domain fluorescence lifetime imaging as method to analyze wood structures}, series = {Conference on Lasers and Electro-Optics}, booktitle = {Conference on Lasers and Electro-Optics}, organization = {Technical Digest Series (Optica Publishing Group, 2022)}, doi = {10.1364/CLEO_AT.2022.JW3A.19}, pages = {JW3A.19}, year = {2022}, abstract = {The analysis of wood structures using FD-FLIM seems promising for the identification of wood at 488 nm, as lignin has a high impact on the fluorescence lifetime.}, language = {en} } @inproceedings{LeiterWohlschlaegerAueretal.2021, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Auer, Veronika and Versen, Martin and Laforsch, Christian}, title = {An algorithmic method to identify multiple wood species in a single image by their specific fluorescence lifetimes}, series = {OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP)}, booktitle = {OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP)}, doi = {10.1364/COSI.2021.CF2B.3}, pages = {CF2B.3}, year = {2021}, abstract = {Fluorescence lifetime imaging microscopy (FLIM) combined with an image processing algorithm is successfully used for the optical identification and areal separation of three wood species of maple, larch and nut in a single taken image.}, language = {en} } @inproceedings{WohlschlaegerHolstVersenetal.2021, author = {Wohlschl{\"a}ger, Maximilian and Holst, Gerhard and Versen, Martin and Laforsch, Christian}, title = {An optical method to differentiate wood from polymers using fluorescence lifetime imaging microscopy}, series = {OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES)}, booktitle = {OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES)}, doi = {10.1364/ES.2021.EW4G.6}, pages = {EW4G.6}, year = {2021}, abstract = {In this contribution investigations with fluorescence lifetime imaging microscopy (FLIM) are made to optically distinguish polymers and wood. The results show that the distinction and identification is possible in a graphical and calculative way.}, language = {en} } @inproceedings{WohlschlaegerVersenLaforsch2022, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian}, title = {Investigation of the Impact of CaCO3 Concentrations on the Fluorescence Lifetime of Polypropylene}, series = {Conference on Lasers and Electro-Optics}, booktitle = {Conference on Lasers and Electro-Optics}, organization = {Technical Digest Series (Optica Publishing Group, 2022)}, doi = {10.1364/CLEO_AT.2022.AM2M.2}, pages = {AM2M.2}, year = {2022}, abstract = {The impact of fillers on the fluorescence lifetime of polymers is still unknown. Investigating polypropylene containing different CaCO3 concentrations using FD-FLIM show an exponential increase in fluorescence lifetime proportional to the CaCO3 density in polypropylene.}, language = {en} }