arXiv subjects

Max Gmelch

Publications and source records attributed to Max Gmelch.

3 recordsLinked to original sources

arXiv2024

Remote Analysis of Femoroacetabular Impingement by a triade of label-free optical spectroscopy techniques

This paper introduces the combination of Laser-induced breakdown spectroscopy (LIBS), Raman spectroscopy (RS) and diffuse reflectance spectroscopy (DRS) in the field of biomedical research. Thereby, the results from RS and LIBS are combined with previous DRS results. These noninvasive optical methods, used together, offer thorough analysis of the absorptive and scattering behaviour, elemental composition, and molecular bindings of tissue, without resulting in considerable harm or changes to the sample or the requirement of markers. The study centres on applying this triad of techniques to tissues affected by Femoroacetabular Impingement (FAI), a condition characterised by reduced hip mobility due to developmental deformities of the hip joint. The research results in a biochemical pathway model of the condition causing the red staining caused by FAI which origin was unknown until now. This proves that this approach may have significant implications for numerous medical applications and support in exploring complex chemical and biochemical pathways.

physics.optics↗

arXiv2022

Accurate wavelength tracking by exciton spin mixing

Wavelength discriminating systems typically consist of heavy benchtop-based instruments, comprising diffractive optics, moving parts, and adjacent detectors. For simple wavelengths measurements, such as lab-on-chip light source calibration or laser wavelength tracking, which do not require polychromatic analysis and cannot handle bulky spectroscopy instruments, light-weight, easy-to-process, and flexible single-pixel devices are attracting increasing attention. Here, we propose a device for wavelength tracking with room-temperature phosphorescence at the heart of its functionality that demonstrates a resolution down to one nanometer and below. It is solution-processed from a single host-guest system comprising organic room-temperature phosphors and colloidal quantum dots. The share of excited triplet states within the photoluminescent layer is dependent on the excitation wavelength and determines the afterglow intensity of the film, which is tracked by a simple photodetector. Finally, an all-organic thin-film wavelength sensor and two applications are demonstrated where our novel measurement concept successfully replaces a full spectrometer.

physics.optics↗

arXiv2020

High-speed and continuous-wave programmable luminescent tags

Most materials recently developed for room temperature phosphorescence (RTP) lack of practical relevance due to their inconvenient crystalline morphology. Using amorphous material systems instead, programmable luminescent tags (PLTs) based on organic biluminescent emitter molecules with easy processing and smooth sample shapes were presented recently. Here, the effective quenching of the emitters RTP by molecular oxygen (O2) and the consumption of the excited singlet O2 through a chemical reaction represent the central features. With customized activation schemes, high resolution content can be written and later erased multiple times into such films, providing a versatile yet simple photonic platform for information storage. However, two important limitations remain: (i) The immutable fluorescence of the emitters outshines the phosphorescent patterns by roughly one order of magnitude, allowing read-out of the PLTs only after the excitation source is turned off. (ii) The programming of these systems is a rather slow process, where lowest reported activation times are still > 8 s. Here, a material-focused approach to PLTs with fast activation times of 120 +/- 20 ms and high-contrast under continuous-wave (cw) illumination is demonstrated, leading to accelerated programming on industry relevant time scales and a simplified readout process both by eye and low cost cameras.

physics.app-ph↗