@inproceedings{DietlmeierRajanLeiteretal.2023, author = {Dietlmeier, Maximilian and Rajan, Aromal Somarajan and Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Klassifizierung von Altholz durch FD-FLIM Bilder mit neuronalen Netzen}, series = {Tagungsband AALE 2023}, booktitle = {Tagungsband AALE 2023}, doi = {10.33968/2023.24}, year = {2023}, abstract = {Holz ist eine der wichtigsten erneuerbaren Ressourcen und kann recycelt werden, wobei derzeit nur unbehandeltes Holz in mehreren Lebenszyklen verwendet werden kann. Allerdings werden in Altholzsortieranlagen meist behandeltes und unbehandeltes Altholz gemischt angeliefert und es gibt keine automatische Klassifizierung zur sortenreinen Sortierung. Fr{\"u}here Studien zeigen, dass behandelte und unbehandelte Holzproben mit Hilfe von bildgebender Fluoreszenzabklingzeit Mikroskopie unterschieden werden k{\"o}nnen. Um den Prozess der Klassifizierung von Altholz anhand von Fluoreszenzabklingzeitbildern zu automatisieren, werden zwei neuronale Netzwerke (NN) evaluiert. Das erste NN ist ein MLP (Multi Layer Perceptron), das das Altholz anhand von Erwartungswert und Standardabweichung eines Fluoreszenzabklingzeitbildes klassifiziert. Das zweite untersuchte NN ist ein CNN (Convolutional Neural Network), das das Holz direkt anhand der Fluoreszenzabklingzeitbilder klassifiziert. Beide Netzwerke sind in Python implementiert, um die sp{\"a}tere Verwendung in einem automatischen Klassifizierungs- und Sortierprozess zu erleichtern. Die Evaluation der NN zeigt vielversprechende Ergebnisse zur automatisierten Klassifikation von Altholz.}, language = {de} } @inproceedings{LeiterDietlmeierWohlschlaegeretal.2023, author = {Leiter, Nina and Dietlmeier, Maximilian and Wohlschl{\"a}ger, Maximilian and L{\"o}der, Martin G.J. and Versen, Martin and Laforsch, Christian}, title = {Development of a Neural Network for Automatic Classification of Post-Consumer Wood Using Rapid-FLIM}, series = {2023 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2023 IEEE Sensors Applications Symposium (SAS)}, doi = {10.1109/SAS58821.2023.10254174}, pages = {1 -- 6}, year = {2023}, abstract = {The economic use of wood is a growing sector, not only because of the significant advantage of wood to retain CO 2 . It is crucial to increase the material recycling of wood in several lifecycles, but currently, there is no reliable post-consumer wood sorting technique in line. This research measures 365 post-consumer wood samples of classes A1-4 four times with the frequency domain fluorescence lifetime imaging microscopy (FD-FLIM) subset method rapid fluorescence lifetime imaging microscopy (Rapid-FLIM). The data is analyzed on their statistical features. Four neural networks based on Multilayer perceptron are then trained and tested with twelve statistical features extracted from the Rapid-FLIM images. The best model for this application contains the optimizer RMSprop, the activation function SELU and the loss function binary crossentropy. The best model of this structure could achieve a false positive ratio of 4.79 \% over the ten folds.}, language = {en} } @inproceedings{ThomasSaleemLeiteretal.2023, author = {Thomas, Amal and Saleem, Shaif and Leiter, Nina and Dietlmeier, Maximilian and Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian and Schwarz, Jonas and Auer, Veronika and Risse, Michael}, title = {Frequency Domain Fluorescence Lifetime Imaging Microscopy (FD-FLIM) analysis of Quercus robur samples for origin differentiation purposes}, series = {Optica Sensing Congress 2023}, booktitle = {Optica Sensing Congress 2023}, year = {2023}, abstract = {The fast classification and identification of plastics presents a significant challenge. The study assesses the suitability of a Multilayer Perceptron to classify and identify commonly found plastic types using Rapid-FLIM, achieving an accuracy of 88.33\%. @inproceedingsSchwarz:23, 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} } @inproceedings{LeiterWohlschlaegerDietlmeieretal.2023, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Dietlmeier, Maximilian and Versen, Martin and L{\"o}der, Martin and Laforsch, Christian}, title = {Comparative Analysis of Fluorescence Properties of Post-Consumer Wood Using FD-FLIM}, series = {2023 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2023 IEEE Sensors Applications Symposium (SAS)}, doi = {10.1109/SAS58821.2023.10254052}, pages = {1 -- 6}, year = {2023}, abstract = {The FD-FLIM technique has a high potential for automated post-consumer wood sorting. A problem of analysing post-consumer wood fluorescence properties is the uncertainty of the post-consumer wood category as the origin of the samples are unknown. In this study, the fluorescence properties of actual post-consumer wood is compared with prepared wood samples. The post-consumer wood samples display slightly different fluorescence intensities and lifetimes due to environmental influences and a higher sample diversity. For improved training of evaluation algorithms for post-consumer wood sorting, the prepared sample set should be extended or the post-consumer wood should be additionally analysed in the laboratory.}, language = {en} } @inproceedings{ThomasSaleemLeiteretal.2023, author = {Thomas, Amal and Saleem, Shaif and Leiter, Nina and Dietlmeier, Maximilian and Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian}, title = {Development of a Neural Network for an Automated Differentiation of Plastics using Rapid-FLIM}, series = {Optica Sensing Congress 2023}, booktitle = {Optica Sensing Congress 2023}, doi = {10.1364/ES.2023.EW4E.5}, year = {2023}, abstract = {The fast classification and identification of plastics presents a significant challenge. The study assesses the suitability of a Multilayer Perceptron to classify and identify commonly found plastic types using Rapid-FLIM, achieving an accuracy of 88.33\%.}, language = {en} } @inproceedings{WohlschlaegerLeiterDietlmeieretal.2023, author = {Wohlschl{\"a}ger, Maximilian and Leiter, Nina and Dietlmeier, Maximilian and L{\"o}der, Martin G.J. and Versen, Martin and Laforsch, Christian}, title = {Comparison of Two Classification Methods Trained with FD-FLIM Data to Identify and Distinguish Plastics from Environmental Materials}, series = {2023 International Joint Conference on Neural Networks (IJCNN)}, booktitle = {2023 International Joint Conference on Neural Networks (IJCNN)}, doi = {10.1109/IJCNN54540.2023.10191054}, pages = {1 -- 9}, year = {2023}, abstract = {Previous research on identifying plastic types and differentiating plastics from environmental material is promising by utilizing the specific fluorescence lifetime, but the evaluation still has to be automated. Therefore, an automated Gaussian analysis is developed for evaluating frequency-domain fluorescence lifetime images of plastics and environmental materials. Furthermore, we applied a "Multilayer Perceptron" and "Random Forest Classifier" to the data resulting from the Gaussian analysis of the frequency domain fluorescence lifetime imaging microscopy data. The classification results show high F1-scores, whereby the best "Multilayer Perceptron" and "Random Forest Classifier" achieved an F1-score of 90\%. Thus, identifying and differentiating plastics and environmental materials is possible by applying a "Multilayer Perceptron" or "Random Forest Classifier" to the Gaussian-analyzed imaged fluorescence lifetime data.}, language = {en} } @inproceedings{WohlschlaegerHolstVersen2020, author = {Wohlschl{\"a}ger, Maximilian and Holst, Gerhard and Versen, Martin}, title = {Automatische Erkennung von Kunststoffen durch bildgebende Fluoreszenzabklingzeitmessung}, series = {Tagungsband: AALE 2020 - Automatisierung und Mensch-Technik-Interaktion 17. Fachkonferenz}, booktitle = {Tagungsband: AALE 2020 - Automatisierung und Mensch-Technik-Interaktion 17. Fachkonferenz}, publisher = {VDE Verlag Berlin}, isbn = {978-3-8007-5180-8}, pages = {223 -- 231}, year = {2020}, language = {de} } @article{WohlschlaegerVersen2020, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Detection of plastics in water based on their fluorescence behavior}, series = {Journal of Sensors and Sensor Systems}, volume = {9}, journal = {Journal of Sensors and Sensor Systems}, number = {2}, pages = {337 -- 343}, year = {2020}, abstract = {Plastic waste is one of the biggest growing factors contributing to environmental pollution. So far there has been no established method to detect and identify plastics in environmental matrices. Thus, a method based on their characteristic fluorescence behavior is used to investigate whether plastics can be detected and identified in tap water under laboratory conditions. The experiments show that the identification of plastics as a function of water depth is possible. As the identification becomes more difficult with higher water depths, investigations with a highly sensitive imaging method were carried out to obtain an areal integration of the fluorescent light and thus better results.}, language = {en} } @inproceedings{LeiterWohlschlaegerAueretal.2021, author = {Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Auer, Veronika and Versen, Martin and Laforsch, Christian}, title = {A Novel Approach to Identify Wood Species Optically using Fluorescence Lifetime Imaging Microscopy}, series = {SMSI 2021 Conference - Sensor and Measurement Science International}, booktitle = {SMSI 2021 Conference - Sensor and Measurement Science International}, pages = {169 -- 170}, year = {2021}, abstract = {This contribution presents the results obtained with fluorescence lifetime imaging microscopy (FLIM)within the optical identification and differentiation of the four wood species walnut, beech, spruce, and maple. The experimental setup as well as the evaluation algorithm, with which the experiments were carried out, is explained briefly.}, language = {en} } @inproceedings{WohlschlaegerVersen2019, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Detektion von Kunststoffen in Wasser mithilfe von Fluoreszenz}, series = {20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019}, booktitle = {20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019}, publisher = {AMA Service GmbH}, address = {Wunstorf}, isbn = {978-3-9819376-0-2}, pages = {687 -- 694}, year = {2019}, abstract = {Die wohl gr{\"o}ßte aktuelle Umweltverschmutzung mit Kunststoffen findet in Ozeanen, Seen und Fl{\"u}ssen statt. Bis jetzt gibt es kein etabliertes Verfahren, mit dem Kunststoffe in Umwelt- bzw. Wassermatrizen detektiert werden k{\"o}nnen. Deshalb wird mit einem Verfahren, welches auf dem Prinzip der Fluoreszenz basiert, untersucht, ob unter Laborbedingungen Kunststoffe in Wasser detektiert und identifiziert werden k{\"o}nnen. Anhand eines mathematischen Modells, einer Simulation und mit Hilfe von optischen Experimenten wird gezeigt, dass der Nachweis und auch eine Identifikation von Kunststoffen in Abh{\"a}ngigkeit der Wassertiefe, mit diesem Verfahren m{\"o}glich ist.}, language = {de} } @inproceedings{WohlschlaegerVersenHolstetal.2019, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and Holst, Gerhard and Franke, Robert}, title = {An Approach of Identifying Polymers With Fluorescence Lifetime Imaging}, series = {2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech)}, booktitle = {2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech)}, pages = {186 -- 189}, year = {2019}, abstract = {Nowadays, fluorescence lifetime measurements and the method of fluorescence lifetime imaging are already state of the art in biomedical research. Also first investigations show that polymers could be identified due to their endogenous fluorescent lifetime. Thus an approach of identifying polymers with fluorescence lifetime imaging is done in this contribution. Therefore, four different polymers are examined and evaluated with statistical methods in order to determine their specific fluorescence lifetimes.}, 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 = {2022 Conference on Lasers and Electro-Optics (CLEO)}, booktitle = {2022 Conference on Lasers and Electro-Optics (CLEO)}, pages = {1 -- 2}, year = {2022}, abstract = {The impact of fillers on the fluorescence lifetime of polymers is still unknown. Investigating polypropylene containing different CaCO 3 concentrations using FD-FLIM show an exponential increase in fluorescence lifetime proportional to the CaCO 3 density in polypropylene.}, language = {en} } @inproceedings{WohlschlaegerHolstVersen2020, author = {Wohlschl{\"a}ger, Maximilian and Holst, Gerhard and Versen, Martin}, title = {A novel approach to optically distinguish plastics based on fluorescence lifetime measurements}, series = {2020 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2020 IEEE Sensors Applications Symposium (SAS)}, doi = {10.1109/SAS48726.2020.9220084}, pages = {1 -- 6}, year = {2020}, abstract = {In medical and biological research, fluorescence lifetime measurements and fluorescence lifetime imaging is already a part of the standardized analysis procedures. As first investigations have shown, polymers can be identified using fluorescence lifetime imaging and an evaluation algorithm. Thus, this contribution pursues a novel approach for the direct differentiation of four polymers with fluorescence lifetime imaging. Therefore, the evaluation algorithm is extended to compare several fluorescence lifetime images to prove that a distinction is possible.}, language = {en} } @inproceedings{WohlschlaegerVersenLaforsch2021, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian}, title = {Non-destructive evaluation of treated polyethylene terephthalate films by fluorescence lifetime imaging}, series = {2021 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2021 IEEE Sensors Applications Symposium (SAS)}, doi = {10.1109/SAS51076.2021.9530008}, pages = {1 -- 5}, year = {2021}, abstract = {The fluorescence decay time allows to identify and distinguish polymers from each other. Three differently treated biaxially-oriented polyethylene terephthalate films are examined with two excitation wavelengths of 445 and 488nm. The fluorescence decay time is dependent of the treatment method of the films and is a means for identification.}, 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 = {Tagungsband AALE 2022, 18. AALE-Konferenz. Pforzheim, 09.03.-11.03.2022}, booktitle = {Tagungsband AALE 2022, 18. AALE-Konferenz. Pforzheim, 09.03.-11.03.2022}, doi = {https://doi.org/10.33968/2022.11}, pages = {115 -- 124}, 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 = {2022 Conference on Lasers and Electro-Optics (CLEO)}, booktitle = {2022 Conference on Lasers and Electro-Optics (CLEO)}, pages = {1 -- 2}, year = {2022}, language = {en} } @inproceedings{WohlschlaegerVersen2019, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin}, title = {Bestimmung einer Quanteneffizienz f{\"u}r das automatisierte Sortieren von Kunststoffen durch Fluoreszenz}, series = {AALE 2019 - Autonome und intelligente Systeme in der Automatisierungstechnik 16. Fachkonferenz}, booktitle = {AALE 2019 - Autonome und intelligente Systeme in der Automatisierungstechnik 16. Fachkonferenz}, editor = {Bauer, Benedict and Wittenberg, Carsten}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-4860-0}, pages = {179 -- 187}, year = {2019}, language = {de} } @inproceedings{WohlschlaegerHolstVersen2020, author = {Wohlschl{\"a}ger, Maximilian and Holst, G. and Versen, Martin}, title = {A novel approach to optically distinguish plastics based on fluorescence lifetime measurements}, series = {2020 IEEE Sensors Applications Symposium (SAS), Kuala Lumpur, Malaysia}, booktitle = {2020 IEEE Sensors Applications Symposium (SAS), Kuala Lumpur, Malaysia}, pages = {1 -- 6}, year = {2020}, language = {en} } @inproceedings{WohlschlaegerVersenLanghals2019, author = {Wohlschl{\"a}ger, Maximilian and Versen, Martin and Langhals, H.}, title = {A method for sorting of plastics with an apparatus specific quantum efficiency approach}, series = {2019 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2019 IEEE Sensors Applications Symposium (SAS)}, year = {2019}, abstract = {Today, the automatic separation of polymers from each other in an industrial scale is an unsolved problem. In laboratory environments, two methods are known whereby plastic is sorted either by color or by fluorescence decay time measurements that require fast synchronization and thus expensive equipment. A simple and pragmatic process is proposed to separate plastics from each other: all fluorescent photons are counted in relation to the absorbed photons. A theoretical model and an experimental setup are built in order to determine an apparatus specific quantum efficiency.}, language = {en} } @inproceedings{ManiyattuGeegyLeiteretal.2022, author = {Maniyattu, Georgekutty Jose and Geegy, Eldho and Leiter, Nina and Wohlschl{\"a}ger, Maximilian and Versen, Martin and Laforsch, Christian}, title = {Development of a neural network to identify plastics using Fluorescence Lifetime Imaging Microscopy}, series = {2022 IEEE Sensors Applications Symposium (SAS)}, booktitle = {2022 IEEE Sensors Applications Symposium (SAS)}, doi = {10.1109/SAS54819.2022.9881372}, pages = {1 -- 6}, year = {2022}, abstract = {Plastics have become a major part of human's daily life. An uncontrolled usage of plastic leads to an accumulation in the environment posing a threat to flora and fauna, if not recycled correctly. The correct sorting and recycling of the most commonly available plastic types and an identification of plastic in the environment are important. Fluorescence lifetime imaging microscopy shows a high potential in sorting and identifying plastic types. A data-based and an image-based classification are investigated using python programming language to demonstrate the potential of a neural network based on fluorescence lifetime images to identify plastic types. The results indicate that the data-based classification has a higher identification accuracy compared to the image-based classification.}, language = {en} } @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} }