Andreas Güntner

Last Name

Güntner

First Name

Andreas

ORCID

0000-0002-4127-752X

Organisational unit

09794 - Güntner, Andreas / Güntner, Andreas

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Publications 1 - 10 of 67

Structure-Function Relationship of Highly Reactive CuOx Clusters on Co₃O₄ for Selective Formaldehyde Sensing at Low Temperatures
D'Andria, Matteo; Krumeich, Frank; Yao, Zhangyi; et al. (2024)
Advanced Science
Designing reactive surface clusters at the nanoscale on metal-oxide supports enables selective molecular interactions in low-temperature catalysis and chemical sensing. Yet, finding effective material combinations and identifying the reactive site remains challenging and an obstacle for rational catalyst/sensor design. Here, the low-temperature oxidation of formaldehyde with CuOₓ clusters on Co₃O₄ nanoparticles is demonstrated yielding an excellent sensor for this critical air pollutant. When fabricated by flame-aerosol technology, such CuOₓ clusters are finely dispersed, while some Cu ions are incorporated into the Co₃O₄ lattice enhancing thermal stability. Importantly, infrared spectroscopy of adsorbed CO, near edge X-ray absorption fine structure spectroscopy and temperature-programmed reduction in H₂ identified Cu⁺ and Cu²⁺ species in these clusters as active sites. Remarkably, the Cu⁺ surface concentration correlated with the apparent activation energy of formaldehyde oxidation (Spearman's coefficient rho = 0.89) and sensor response (0.96), rendering it a performance descriptor. At optimal composition, such sensors detected even the lowest formaldehyde levels of 3 parts-per-billion (ppb) at 75 degrees C, superior to state-of-the-art sensors. Also, selectivity to other aldehydes, ketones, alcohols, and inorganic compounds, robustness to humidity and stable performance over 4 weeks are achieved, rendering such sensors promising as gas detectors in health monitoring, air and food quality control.
Highly selective detection of methanol over ethanol by a handheld gas sensor
van den Broek, Jan; Abegg, Sebastian; Pratsinis, Sotiris E.; et al. (2019)
Nature Communications
Methanol poisoning causes blindness, organ failure or even death when recognized too late. Currently, there is no methanol detector for quick diagnosis by breath analysis or for screening of laced beverages. Typically, chemical sensors cannot distinguish methanol from the much higher ethanol background. Here, we present an inexpensive and handheld sensor for highly selective methanol detection. It consists of a separation column (Tenax) separating methanol from interferants like ethanol, acetone or hydrogen, as in gas chromatography, and a chemoresistive gas sensor (Pd-doped SnO2 nanoparticles) to quantify the methanol concentration. This way, methanol is measured within 2 min from 1 to 1000 ppm without interference of much higher ethanol levels (up to 62,000 ppm). As a proof-of-concept, we reliably measure methanol concentrations in spiked breath samples and liquor. This could enable the realization of highly selective sensors in emerging applications such as breath analysis or air quality monitoring.
Handheld methanol detector for beverage analysis: interlaboratory validation
van den Broek, Jan; Keller, Sebastian D.; Goodall, Ian; et al. (2024)
Analytical Methods
Methanol is a toxic alcohol contained in alcoholic beverages as a natural byproduct of fermentation or added intentionally to counterfeits to increase profit. To ensure consumer safety, many countries and the EU have established strict legislation limits for methanol content. Methanol concentration is mostly detected by laboratory instrumentation since mobile devices for routine on-site testing of beverages in distilleries, at border stations or even at home are not available. Here, we validated a handheld methanol detector for beverage analysis in an ISO 5725 interlaboratory trial: a total of 119 measurements were performed by 17 independent participants (distilleries, universities, authorities, and competence centers) from six countries on samples with relevant methanol concentrations (0.1, 1.5 vol%). The detector was based on a microporous separation filter and a nanostructured gas sensor allowing on-site measurement of methanol down to 0.01 vol% (in the liquid) within only 2 min by laymen. The detector showed excellent repeatability (<5.4%), reproducibility (<9.5%) and small bias (<0.012 vol%). Additional measurements on various methanol-spiked alcoholic beverages (whisky, rum, gin, vodka, tequila, port, sherry, liqueur) indicated that the detector is not interfered by environmental temperature and spirit composition, featuring excellent linearity (R2 > 0.99) down to methanol concentrations of 0.01 vol%. This device has been recently commercialized (Alivion Spark M-20) with comparable accuracy to the gold-standard gas chromatography and can be readily applied for final product inspection, intake control of raw materials or to identify toxic counterfeit products.
3D printing by two-photon polymerization of hollow microneedles for interstitial fluid extraction
Elias Abi-Ramia Silva, Tiago; Kohler, Stephan; Bartzsch, Nicolas; et al. (2024)
arXiv
Dermal interstitial fluid (ISF) is a rich source of biomarkers (e.g., glucose) that can be used for continuous health monitoring with wearable sensors. Hollow microneedle devices are a promising solution to extract ISF on demand by penetrating the skin with minimal pain. However, they rely on inserting bio-incompatible materials (e.g., silicon) into individuals, limiting the application time. Here, the direct 3D printing of polymer hollow microneedles on silicon-based microfluidic devices and the successful in-vivo extraction of ISF are demonstrated. Our additive manufacturing approach enables the versatile combination of materials and rapid prototyping of microneedle geometry. After improving the design through finite element modeling, a hollow microneedle geometry was printed by two-photon polymerization and experimentally characterized with mechanical and fluidic tests. Microneedles were fabricated with high accuracy (i.e., 997 +/- 2 um) and reliably interfaced with the microfluidic chip (i.e., centerline alignment within 5% of diameter). The needles demonstrated sufficient mechanical strength (i.e., 411 +/- 3 mN per needle) to endure at least 10 consecutive insertions into simulated skin. Biocompatibility and ISF extraction were demonstrated in an in-vivo 72-hour test, showing the safety and reliability of our approach. Such a platform is promising for minimally invasive, continuous monitoring of biomarkers in ISF, aiding in medical diagnoses and personalized health treatments.
Zeolite membranes for highly selective formaldehyde sensors
Güntner, Andreas; Abegg, Sebastian; Wegner, Karsten; et al. (2018)
Sensors and Actuators B: Chemical
The road to commercializing the mobile methanol detector Alivion Spark M-20
Güntner, Andreas; D’Andria, Matteo; van den Broek, Jan (2023)
Nature Reviews Bioengineering
The Spark M-20 is a nanotechnology-based, handheld device that detects toxic methanol in beverages and sanitizers, which may soon also be applied for intoxication screening in human breath. Here, we share our pathway and experiences during the translation of this university-originated innovation into a commercial product that today is serving customers in 23 countries on 6 continents.
Monitoring breath markers under controlled conditions
Righettoni, Marco; Ragnoni Alessandro; Güntner, Andreas; et al. (2015)
Journal of Breath Research
CuOx – enriched Co3O4 surfaces enable selective formaldehyde sensing at low temperature
D'Andria, Matteo; Krumeich, Frank; Wang, Ryan; et al. (2023)
ChemRxiv
Designing highly reactive surface clusters at the nanoscale on metal-oxide supports enables selective molecular interactions in low-temperature catalysis and chemical sensing. Yet, finding effective material combinations and identifying the reactive site remains challenging and a key obstacle for rational catalyst/sensor design. Here, we demonstrate the low-temperature oxidation of formaldehyde with CuOx clusters on Co3O4 nanoparticles yielding an excellent sensor for this critical air pollutant. When fabricated by flame-aerosol technology, such CuOx clusters are finely dispersed onto the surface, while some Cu ions are incorporated into the Co3O4 lattice enhancing thermal stability. Most importantly, infrared spectroscopy of adsorbed CO and temperature-programmed reduction in H2 identified Cuδ+ species in these clusters as active sites. In fact, its surface concentration correlated with the apparent activation energy of formaldehyde oxidation (Spearman’s coefficient ρ = 0.89) and sensor response (0.96). At optimal composition, such sensors detected even the lowest formaldehyde levels of 3 parts-per-billion at 75 °C, superior to the state-of-the-art sensors. Also, selectivity to other aldehydes, ketones, alcohols, and inorganic compounds, robustness to relevant humidity levels and stable performance over 4 weeks were achieved, rendering such sensors promising as low-power gas detectors in air and food quality control as well as in health monitoring.
Monitoring of selected skin- and breath-borne volatile organic compounds emitted from the human body using gas chromatography ion mobility spectrometry (GC-IMS)
Mochalski, Paweł; Wiesenhofer, Helmut; Allers, Maria; et al. (2018)
Journal of Chromatography B
Catalytic filters for metal oxide gas sensors
Weber, Ines C.; Güntner, Andreas (2022)
Sensors and Actuators B: Chemical
Chemical sensors based on metal oxides (MOx) are most promising for emerging applications including medical breath analysis, distributed environmental monitoring and rapid food quality assessment. Yet, such sensors are not established in daily practice, mainly due to their limited selectivity, sensitivity and stability. Catalytic filters offer an effective solution to improve these by converting interferants to inactive species and/or target analytes to more responsive ones. This has been exploited successfully for alkane sensors, enabling their commercial utilization. Here, catalytic filters are discussed as promising tool to optimize the performance of chemoresistive MOx sensors. First, we provide an overview of chemical and physical parameters that govern the catalytic reactivity of such filters and we compare their implementation as overlayers and packed beds. Thereby, recent advances in the nanoscale design of suitable materials to finely tune their catalytic properties are elaborated. Next, filter solutions for analytes of various chemical families (including alkanes, alkenes, inorganics, alcohols, ketones and aromatics) are discussed and quantitatively compared also to other state-of-the-art detectors. Emphasis is placed on present challenging scenarios, for instance, the distinction of analytes from significantly higher concentrated interferants (e.g., breath markers in the presence of background ethanol in hospitals) or chemically similar compounds (e.g., benzene from xylene and toluene in air quality assessment). This is followed by examples demonstrating the integration of such filter-sensor concepts into devices and their evaluation under real conditions. Finally, opportunities and research frontiers are highlighted to inspire future research.

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Andreas Güntner

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