Wolfgang Petrich

Wolfgang Petrich
Roche

Prof. Dr.

About

88
Publications
14,943
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,516
Citations
Citations since 2016
14 Research Items
1572 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300

Publications

Publications (88)
Article
Full-text available
Diagnostic procedures, therapeutic recommendations, and medical risk stratifications are based on dedicated, strictly controlled clinical trials. However, a plethora of real-world medical data exists, whereupon the increase in data volume comes at the expense of completeness, uniformity, and control. Here, a case-by-case comparison shows that the p...
Article
Mid-infrared spectroscopy has been applied to research in biology and medicine for more than 20 years and conceivable applications have been identified. More recently, these applications have been shown to benefit from the use of quantum cascade lasers due to their specific properties, namely high spectral power density, small beam parameter produc...
Article
Continuous glucose monitoring enables an improved disease management for people with diabetes. However, state-of-the-art, enzyme-based, minimally invasive sensors loose their sensitivity over time and have to be replaced periodically. Here, we present the in vitro investigation of a quantum cascade laser-based measurement scheme that conceptually s...
Article
A laser’s high degree of coherence leads to interferences, which ‐ in the absence of precautions ‐ can cause severe image distortions such as fringes and speckles and which thereby strongly hamper a meaningful interpretation of hyperspectral images in laser‐based widefield microspectroscopy. While images and spectra of homogenous samples may alread...
Article
The optical properties of skin in the mid-infrared range are not known, despite their importance for e.g. non-invasive glucose monitoring. In this paper, transmission, absorption, scattering, and reduced scattering coefficients are quantified using a custom-built goniometer based on a quantum cascade laser operated at the glucose absorption band at...
Article
Reliable human activity recognition with wearable devices enables the development of human-centric pervasive applications. We aim to develop a robust wearable-based activity recognition system for real life situations where the device position is up to the user or where a user is unable to collect initial training data. Consequently, in this work w...
Article
Full-text available
Duncan Graham opened a general discussion of the paper by Pavel Matousek: Regarding the temperature measurements, how did you do them? Stokes/anti-Stokes measurement? The values are not what I'd expect and seem lower. What was the wavelength and power of the laser and did you calculate what you thought the temperature measurement should be based on...
Article
Full-text available
Parvez Haris opened the discussion of the introductory lecture by Max Diem: Varying degrees of accuracy have been obtained for discrimination between cancerous and non-cancerous tissues using vibrational spectroscopic methods. What are the explanations for these variation in accuracy between cancerous and non-cancerous tissues and how do they corre...
Article
Richard Dluhy opened a general discussion of the paper by Duncan Graham: In your example of a heterogeneous solution-based assay for multicomponent analysis, what is the concentration of the target fungal ssPCR DNA that is used, and how do you manage the kinetics of the reaction such that the target reaches the probe in a time frame appropriate for...
Article
The Faraday Discussion meeting "Advanced Vibrational Spectroscopy for Biomedical Applications" provided an excellent opportunity to share and discuss recent research and applications on a highly interdisciplinary level. Spectral pathology, single cell analysis, data handling, clinical spectroscopy, and the spectral analysis of biofluids were among...
Conference Paper
A detailed knowledge of optical properties of tissue is important for the development of non-invasive monitoring systems for clinical practice. However, tissue optical properties are rarely known in the mid-infrared wavelength range. Goniometry offers an opportunity to determine in particular the scattering properties of tissue. Here, a custom-buil...
Conference Paper
Infrared microscopy can be performed to observe dynamic processes on a microscopic scale. Fourier-transform infrared spectroscopy-based microscopes are bound to limitations regarding time resolution, which hampers their potential for imaging fast moving systems. In this manuscript we present a quantum cascade laser-based infrared microscope which o...
Article
The large mid-infrared absorption coefficient of water frequently hampers the rapid, label-free infrared microscopy of biological objects in their natural aqueous environment. However, the high spectral power density of quantum cascade lasers is shifting this limitation such that mid-infrared absorbance images can be acquired in situ within signal-...
Article
Full-text available
The speed and efficiency of quantum cascade laser-based mid-infrared microspectroscopy are demonstrated using two different model organisms as examples. For the slowly moving Amoeba proteus, a quantum cascade laser is tuned over the wavelength range of 7.6 µm to 8.6 µm (wavenumbers 1320 cm(-1) and 1160 cm(-1) , respectively). The recording of a hyp...
Article
Full-text available
We report on the successful measurement of surface-enhanced infrared vibrational spectra from a few nanometer thick organic semiconductor layers on samples with resonant plasmonic nanoantennas arranged in arrays. For the first time, a setup with a tunable quantum cascade laser as the light source in mid-infrared range is used. The combination of th...
Article
Full-text available
Changes in the volume covered by mucin-secreting goblet cell regions within colon thin sections may serve as a mean to differentiate between ulcerative colitis and infectious colitis. Here we show that the rapid, quantum cascade laser-based mid-infrared microspectroscopy might be able to contribute to the differential diagnosis of colitis ulcerosa,...
Article
Full-text available
Background The discharge of the Cnidarian stinging organelle, the nematocyst, is one of the fastest processes in biology and involves volume changes of the highly pressurized (150 bar) capsule of up to 50%. Hitherto the molecular basis for the unusual biomechanical properties of nematocysts has been elusive, as their structure was mainly defined as...
Patent
The invention relates to compounds, which are useful for intramolecular fluorescence resonance energy transfer (FRET), comprising the oxidized form of a carbaNADH-based first fluorophore and a second fluorophore that is excitable at a wave-length of between 445 to 540 nm and that has an emission maximum of greater than 560 nm, and methods, kits and...
Article
The spectroscopy of analyte-specific molecular vibrations in tissue thin sections has opened up a path toward histopathology without the need for tissue staining. However, biomedical vibrational imaging has not yet advanced from academic research to routine histopathology due to long acquisition times for the microscopic hyperspectral images and/or...
Article
Today´s minimally-invasive biosensors are often based on chemical reagents and suffer from e.g. oxygen dependence, toxic reaction products, excess analyte consumption and/or degradation of the reagents. Here, we show the first successful analyte quantification by means of a minimally-invasive sensor in vivo, which does not use chemical reactions. T...
Article
Despite the successes of mid-infrared hyperspectral imaging in a research environment, progress in the migration of technology into the day-to-day clinical application is slow. Clinical acceptance may be improved if the spectroscopy would be faster and the infrared microscopes available at lower cost. Here we present first results of a fast, multi-...
Article
The evaporation of water from open u-shaped microchannel grooves was investigated with particular emphasis on the roles of channel width and air flow conditions. Given the small dimensions of the microchannels, all measurements were conducted in a range where convection and diffusion are of equal importance and known correlations for the calculatio...
Patent
Full-text available
The invention relates to a test element for detecting at least one analyte in a sample, in particular for detecting at least one metabolite in a bodily fluid. The test element comprises at least one test field with a test field surface. The test field comprises at least one detection reagent that is adapted to undergo a detectable reaction in the p...
Patent
Full-text available
The invention relates to processes and devices for detecting an analyte in a sample by fluorescence measurement of a fluorophore, wherein the detection medium which contains a fluorophore or a precursor of the fluorophore is admixed with an absorber whose absorbance spectrum superimposes the fluorescence excitation range of the fluorophore. The sys...
Chapter
The fundamental vibrations of the molecules that are most relevant to biology or medicine may be investigated usingelectromagnetic radiation in the mid-infrared spectral range. However, because water constitutes an essential ingredientof biomedical samples and exhibits a strong absorption in the mid-infrared spectral region, means had to be found t...
Article
Carba nicotinamide adenine dinucleotide (cNAD) may serve as a stable cofactor for the enzyme-based detection of glucose. Many characteristics of cNAD and its reduced form cNADH resemble those of NAD and NADH, respectively. The fluorescence lifetimes of cNADH are determined to be 0.32(2) ns and 0.66(3) ns compared to 0.28(2) ns and 0.60(3) ns for NA...
Article
Diabetes mellitus is a disorder of glucose metabolism and it is one of the most challenging diseases, both from a medical and economic perspective. People with diabetes can benefit from a frequent or even continuous monitoring of their blood glucose concentrations. The approach presented here takes advantage of the observational nature of biomedica...
Article
Fluorescence lifetime-based glucose sensing does not depend on fluctuations of the intensity of the light source, light scattering, or changes in the transmission of optical components. Here we demonstrate the sensing of glucose based on the fluorescence lifetime properties of dihydro nicotinamide adenine dinucleotide (NADH), which is reduced from...
Article
The standard agent glucose has been the subject of numerous experimental and theoretical studies, especially in the aqueous environments which are present in most biochemical processes. The impact of the solvation process on the vibrational spectra of glucose in the mid-infrared region is investigated in this work. The computational study focused b...
Article
The continuous surveillance of glucose concentration reduces short-term risks and long-term complications for people with diabetes mellitus, a disorder of glucose metabolism. As a first step towards the continuous monitoring of glucose, reagent-free transmission spectroscopy in the mid-infrared region has been carried out in vitro using a quantum c...
Article
Present data acquisition and/or analysis tools such as OPUS (Bruker Optics), Perkin Elmer's Spotlight software (Perkin Elmer), Resolutions Pro (Varian), Grams (Thermo Fisher Scientific), The Unscrambler (CAMO), CytoSpec (www.cytospec.com) or various Matlab (The MathWorks) toolboxes allow for the easy recording and evaluation of infrared spectra. Ho...
Article
The continuous monitoring of the concentration of glucose provides an essential tool for the improved glycemic control for people with diabetes. Most of the present approaches of transcutaneous, continuous glucose monitors are based on chemical detection and require the insertion of reagents into the body. In contrast, we aim at the reagent-free mo...
Article
Full-text available
Regularized regression methods such as principal component or partial least squares regression perform well in learning tasks on high dimensional spectral data, but cannot explicitly eliminate irrelevant features. The random forest classifier with its associated Gini feature importance, on the other hand, allows for an explicit feature elimination,...
Article
Full-text available
A total of 1,429 serum samples from 389 consecutive patients with acute chest pain were analyzed with the goal to aid the rapid diagnosis of acute myocardial infarction. To the best of our knowledge this is the largest and most comprehensive study on mid-infrared spectroscopy in cardiology. We were able to identify those signatures in the mid-infra...
Chapter
Aspects in the Design of Clinically Relevant Studies in Biomedical Vibrational Spectroscopy The Role of Noise and Reproducibility in the Raw Spectra Safeguarding the Analysis of Data and Its Interpretation Conclusion Acknowledgments References
Article
Full-text available
A hierarchical scheme has been developed for detection of bovine spongiform encephalopathy (BSE) in serum on the basis of its infrared spectral signature. In the first stage, binary subsets between samples originating from diseased and non-diseased cattle are defined along known covariates within the data set. Random forests are then used to select...
Article
The application of mid-infrared laser spectroscopy to the reagent-free quantification of the concentration of glucose was investigated using cryogenically cooled lead salt lasers or, alternatively, quantum cascade lasers operating at room temperature. The concentration of glucose in aqueous solutions was quantified by means of fiber-based attenuate...
Article
Mid-infrared and Raman spectroscopy together with multivariate data analysis offers the potential to be applied to clinical laboratory analysis due to their reagent-free nature, the speed of analysis and the possibility of obtaining a variety of information from a single measurement. In what we believe to be among the largest studies on mid-infrare...
Article
Mid-infrared or Raman spectroscopy together with multivariate data analysis provides a novel approach to clinical laboratory analysis, offering benefits due to its reagent-free nature, the speed of the analysis and the possibility of obtaining a variety of information from one single measurement. We compared mid-infrared and Raman spectra of the se...
Article
Full-text available
The continuous monitoring of glucose allows for tighter control of the glucose concentration and thus may prevent hyper- and hypoglycemia as well as long-term complications of diabetes. While most current systems depend on the transport of fluid to a glucose sensor outside the body, we investigate the possibility of implanting a reagent-based senso...
Article
Full-text available
The fast and reliable determination of concentrations of blood, plasma or serum constituents is a major requirement in clinical chemistry. We explored Raman spectroscopy as a reagent-free tool for predicting the concentrations of different parameters in serum and serum ultrafiltrate. In an investigation using samples from 247 blood donors (which we...
Article
Full-text available
Signatures of Bovine Spongiform Encephalopathy (BSE) have been identified in serum by means of “Diagnostic Pattern Recognition (DPR)”. For DPR-analysis, mid-infrared spectroscopy of dried films of 641 serum samples was performed using disposable silicon sample carriers and a semi-automated DPR research system operating at room temperature. The comb...
Article
Full-text available
In our former studies a diagnostic approach for the detection of transmissible spongiform encephalopaties (TSE) based on FT-IR spectroscopy in combination with artificial neural networks was described, based on a controlled animal study with terminally ill Syrian hamsters and control animals. As a consequence of the bovine spongiform encephalopathy...
Article
The identification and analysis of disease-specific signatures in mid-infrared spectra of serum forms the basis of a method called "Diagnostic Pattern Recognition (DPR)". A conceivable usage of this method in clinical diagnostics requires that the method be applied in a convenient and robust manner. Thus, automation, room-temperature operation and...
Article
Full-text available
Design and functionality of a reagent-free Raman-based fiber optic sensor are described in the context of glucose monitoring. Theoretical calculations of sensor performance are shown using raytrace software. An optimized sensor design with an outer diameter of 1.5 mm was carried out. First experiments in aqueous glucose solutions showed a root mean...
Article
Full-text available
Since 1986, more than 180 000 clinical cases of bovine spongiform encephalopathy (BSE) have been observed in the U.K. alone. Most of these cases were confirmed by postmortem examination of brain tissue. However, BSE-related risk assessment and risk management would greatly benefit from antemortem testing on living animals. A serum-based test could...
Article
The vicious circle of insulin resistance and hyperinsulinemia is considered to precede the manifestation of diabetes type-2 by decades and the corresponding cluster of risk factors is described as the "insulin resistance syndrome" or "metabolic syndrome". Since the present diagnosis of insulin resistance is expensive, time consuming and cumbersome,...
Article
We observed differences between the mid-infrared spectra of sera originating form healthy volunteers and from patients with diabetes mellitus or rheumatoid arthritis (RA). These differences were found to be significant within particular regions of the spectrum both in terms of the χ2 test as well as the Kolmogorov–Smirnov significance level. Compar...
Article
In view of the importance of the diagnosis of rheumatoid arthritis, a novel diagnostic method based on spectroscopic pattern recognition in combination with laboratory parameters such as the rheumatoid factor is described in the paper. Results of a diagnostic study of rheumatoid arthritis employing this method are presented. The method uses classif...
Article
The spectroscopy of molecular vibrations using mid-infrared or Raman techniques has been applied to samples of human tissue or body fluids. This review gives examples for its potential in supporting medical diagnostics. Most of the investigations have been performed in the field of internal medicine, namely angiology, hematology, rheumatology, endo...
Article
We observed differences between the mid-infrared spectra of sera originating from healthy volunteers and from patients with diabetes mellitus or rheumatoid arthritis. These differences were found to be significant in terms of the Fisher criterion, the t-test, and the Kolmogorov-Smirnov test. The significance allows for a classification of the spect...
Article
To benefit from the full information content of the mid-IR spectra of human sera, we directly related the overall shape of the spectra to the donors' disease states. For this approach of disease pattern recognition we applied cluster analysis and discriminant analysis to the example of the disease states diabetes type 1, diabetes type 2, and health...
Article
Vibrational spectra in the mid-infrared region show significant and reproducible correlation with the disease state of the blood donor. When focusing our "disease pattern recognition (DPR)" approach onto the example of diabetes mellitus we can clearly separate samples obtained from healthy volunteers from those samples which originated from diabete...
Article
Die Untersuchung von Blut auf der Basis von chemischen, reagenzgetragenen Analysen bildet einen Schwerpunkt der medizinischen Diagnostik. Darüber hinaus erlauben auch rein physikalische, reagenzfreie Methoden wie die Spektroskopie von Blutserum im mittleren Infrarot einen Einblick in die molekulare Struktur der Probe. Mit Augenmerk auf den medizini...
Article
Eines der herausragendsten Ergebnisse der theoretischen Quantenstatistik ist die Vorhersage, daß Teilchen mit ganzzahligem Drehimpuls bei sehr großer Dichte und/oder sehr geringer Temperatur in einen gemeinsamen Quantenzustand kondensieren können. Als 1924 diese Bose-Einstein-Kondensation eines idealen — also wechselwirkungsfreien — Gases vorherges...
Article
Experimentelle Entwicklungen innerhalb der letzten zwanzig Jahre ermöglichen es, Gase bis auf Temperaturen von weniger als 20 milliardstel Kelvin abzukühlen. Diese Fortschritte eröffnen der physikalischen Forschung vollkommen neue Bereiche, wie die Realisierung des Bose-Einstein-Kondensats eines nahezu idealen Teilchengases.
Article
We describe a new type of magnetic trap whose time-averaged, orbiting potential (TOP) supplies tight and harmonic confinement of atoms. The TOP trap allows for long storage times even for cold atom samples by suppressing the loss due to nonadiabatic spin flips which limits the storage time in an ordinary magnetic quadrupole trap. In preliminary exp...
Article
We have demonstrated an order of magnitude increase in the number and in the lifetime of magneto-optically trapped 87Rb atoms collected from a low-pressure vapor. The improvement results from the reduction of light-assisted collision losses and is achieved by shelving the atomic population into the lower hyperfine ground state. Large fractional pop...
Article
We investigate the behavior of a cloud of atoms in a magneto-optical trap, which—after collection—is compressed when the field gradients of the trap magnetic field are increased. We measure sizes and shapes of the atom cloud as a function of laser detuning, magnetic field gradient, and number of trapped atoms. A transient density increase of more t...
Article
A longitudinal laser cooling of ion beams at about 5% of the velocity of light has been performed at the Heidelberg Test Storage Ring with various cooling schemes employing the spontaneous force. For a 7.29-MeV 9Be+ beam with an initial longitudinal temperature of 2700 K, the main characteristics of laser cooling in a storage ring are discussed. Wh...
Article
We have performed for the first time precision spectroscopy on a coasting fast7Li+ ion beam in a storage ring. The ion beam moving with 6.4% speed of light was first electron cooled and then merged with two counterpropagating laser beams acting on two different hyperfine transitions sharing a common upper level (-system). One laser was frequency lo...