The Austrian Research Center for Non-Destructive Testing (RECENDT) is solving challenges of the modern industry by developing next-generation spectroscopic measurement solutions using NIRONE sensors.
A growing number of industrial branches is using in-situ process information to achieve optimum production efficiency and constant product quality. Since decades, near-infrared (NIR) spectroscopy is one of the most widely used tools to obtain inline process information, mainly due to its low running costs and its ability to simultaneously measure multiple chemical and material parameters, enabled by the use of multivariate modelling and machine learning algorithms1.
The research institute RECENDT, located in Linz (Austria) has been developing substantial expertise in the application of NIR spectroscopy in industrial environments. Nowadays, RECENDT is one of the leading providers of customer-specific spectroscopic measurement solutions, covering the whole method development process – from the laboratory screening and feasibility assessment to sensor development and chemometric modeling until the final industrial implementation of NIR measurement technology and model maintenance.
Several years ago, RECENDT was among the first to recognize the enormous potential of novel MEMS-based NIR spectrometer technology. This new generation of NIR sensors not only significantly lowers hardware costs, but helps to make this technology more accessible, especially for smaller businesses, and at the same time allows for an intensification of the industrial real-time monitoring. Instead of a single 19” rack-sized process spectrometer one can realize more than ten NIR sensors for the same hardware costs: “Conventional NIR process spectrometers usually cost more than 20,000 Euros, which is often a major obstacle for the implementation of this highly potent technology in the industrial environment”, says Markus Brandstetter, Head of the Infrared & Raman Spectroscopy Group at RECENDT. “By significantly lowering the price of implementation, MEMS-based technology increases the accessibility of NIR spectroscopy, especially for industries with high cost-pressure, such as food production.”
Making industry smarter
Apart from the low price, NIRONE Sensors offer a compact form factor and high ruggedness, which allows positioning them close to the process. This makes elaborate optical fiber networks and multiplexing, which is often necessary in industrial NIR monitoring, obsolete. Despite saving money on optical fibers and high installation expenditures, this also leads to fewer possible error sources and decreased signal loss.
The cost-efficient design of NIRONE sensors allows the implementation of multiple sensors at different measurement positions for simultaneous measurements at a reasonable price. Using chemometric modeling, machine learning algorithms, and artificial intelligence, the data from multiple NIRONE sensors can be analyzed automatically and merged with other process data to deliver valuable information about the production process in real-time. Through tight process control using the available NIR data, this enables smarter and more efficient processes by saving energy (e.g. in drying processes) and reduced downtime, leading to significant economic benefits and lower CO2 footprints in the industry.
Endless application possibilities
The possible applications for MEMS-based NIR spectroscopy in the industry are almost endless and cover the whole process chain, starting from raw materials analysis, over process monitoring to product quality control. RECENDT, as one of the early adaptors of this technology, has already demonstrated the potential of NIRONE sensors and implemented them in industrial environments for automated real-time process monitoring purposes. “Despite the reduced resolution and smaller spectral bandwidth, when compared to conventional NIR process spectrometers, NIRONE sensors offer enough spectral information for most industrial applications”, says Robert Zimmerleiter, specialist for industrial application of NIR spectroscopy at RECENDT. “We already had multiple cases where NIRONE sensors provided the ideal sensor solution for industrial applications due to their stability, high ruggedness and compact form factor.”
An industrial application example is the inline monitoring of a polymerization process of melamine formaldehyde resin2. The performance of the NIRONE sensor was tested and found to be comparable to that of a conventional Fourier-transform NIR (FTNIR) spectrometer, previously implemented in the production plant. These impressive results led to the implementation of NIRONE sensor technology for the inline measurement of formaldehyde concentration in formalin, one of the main ingredients for the resin production, at the production plant3.
NIRONE sensors have also been successfully implemented for contactless inline moisture measurements by RECENDT. Their ability to clearly resolve the water absorption band in the NIR spectral region allows for precise measurements of moisture with an accuracy down to about 0.1%. Moisture measurements are of high interest for numerous industrial branches including wood, pulp & paper, chemical, brickworks, pharmaceutical and food industry, where strict limits have to be adhered to when it comes to the water content of the products. Here the NIRONE sensor offers the perfect sensing solution due to its compact size and adaptive nature and thus helps to avoid huge energy waste by providing real-time moisture values for process control.
As demonstrated in a recently published scientific article, another promising application for NIRONE sensors is bioprocess monitoring4. Scientists of RECENDT have combined two NIRONE sensor modules for the real-time monitoring of biomass, phenoxyacetic acid and penicillin in a fed-batch Penicillium chrysogenum fermentation process. Moreover, it was possible to conduct the measurement in a non-invasive fashion, by measuring through the glass wall of the bioreactor using the NIRONE sensors’ integrated light sources. Since the living cells exploited in bioprocesses are very sensitive to their surroundings, an inline capable measurement of important process parameters is essential to ensure high product yield and quality. As demonstrated, NIRONE sensors offer an elegant and effective sensing solution for this measurement problem.
Furthermore, NIRONE sensors have been applied for real-time monitoring of resin curing in the production of complexly formed fiber-reinforced plastic composites using a cascaded injection process. Additionally, through multivariate data analysis, the mixing ratio of the used two-component polymer system was simultaneously determined using the same sensor module. The real-time monitoring of the polymer curing and mixing ratio enabled the application of a significantly faster production process, supported by the real-time information about curing kinetics and determination of the curing endpoint.
Other application examples include thickness measurements of multilayer polymer films, measurement of the charging state of sorptive materials, as well as NIR-based material identification for plastics recycling. Certainly, the future will reveal many additional industrial application-scenarios where NIRONE sensors will be the core component of the sensing solution of choice.
Future of industrial inline NIR process control
Demands for higher sustainability as well as increased efficiency in industrial production will undoubtedly lead to an increased demand for inline process monitoring across all industrial branches in the near future. This in turn, requires sensing technologies to fulfill this demanding measurement task, for which NIR spectroscopy is among the most capable due to its flexible and non-destructive nature. Up to now, the high price point of this already decades-old technology often made its implementation a hard pill to swallow, especially for smaller production plants. With new and reliable MEMS-based NIR spectrometer technology such as the NIRONE sensor, the entry hurdle is significantly reduced and new, previously unthinkable applications are enabled due to the rugged and compact nature of the technology.
Through the help of research institutes such as RECENDT, it is just a matter of time before MEMS-based sensing technology will be applied more and more in the industry and the huge potential of this technology can finally be exploited to facilitate a more sustainable and efficient industry through smarter production processes.
RECENDT acknowledges financial support provided by the Austrian Research Promotion Agency (FFG) under the scope of the COMET programme within the research project Photonic Sensing for Smarter Processes (PSSP) (contract no. 871974) and the Austrian Competence Centre for Feed and Food Quality, Safety and Innovation (FFoQSI), funded by the Austrian ministries BMVIT, BMDW and the Austrian provinces Niederoesterreich, Styria, Upper Austria, and Vienna.
About the writers:
Robert Zimmerleiter, MSc. is researcher at RECENDT with an educational background in physics. He is mainly concerned with the development and application of industrial spectroscopic sensing solutions as well as chemometric data analysis with a special focus on cost-efficient and compact MEMS-based spectrometer technology.
Dr. Markus Brandstetter is the Head of the Infrared & Raman Group at RECENDT. He has more than ten years of experience in the field of spectroscopy and has published over 35 peer-reviewed journal papers. His main research focus is the development of novel spectroscopic measurement solutions, such as miniaturized industrial sensors and mid-infrared laser based instrumentation.
- Pasquini C. Near infrared spectroscopy: Fundamentals, practical aspects and analytical applications. J Braz Chem Soc. 2003;14(2):198-219. doi:10.1590/S0103-50532003000200006
- Nikzad-Langerodi R, Lughofer E, Cernuda C, et al. Calibration model maintenance in melamine resin production: Integrating drift detection, smart sample selection and model adaptation. Anal Chim Acta. 2018;1013:1-12. doi:10.1016/j.aca.2018.02.003
- Zimmerleiter R, Reischer T, Koppensteiner R, Roßbory M, Brandstetter M. Inline measurement of formaldehyde concentration in an industrial production plant by NIR microspectrometer technology. doi:10.13140/RG.2.2.20282.34249
- Zimmerleiter R, Kager J, Nikzad-Langerodi R, et al. Probeless non-invasive near-infrared spectroscopic bioprocess monitoring using microspectrometer technology. Anal Bioanal Chem. December 2019:1-7. doi:10.1007/s00216-019-02227-w