A German research institute even sees applications at home, for example distinguishing similar substances such as sugar and salt, an interchange that is of great importance in food preparation.
Complex composition analyzes can also provide information about the quality, ripeness or freshness of products.
That is why Fraunhofer IPMS researches and develops the smallest energy-efficient scanner systems, which enable contactless and mobile freshness testing on site.
Freshness testing using near infrared spectral analysis
In the field of analysis of materials in general, but especially in the case of food and its freshness, near infrared (NIR) spectral analysis is a proven method in laboratory use. High-precision instruments can provide accurate information about the condition of the product at the time of measurement.
However, it becomes problematic when the sample changes in the period between sampling and measurement in the lab, or when results are needed quickly. Many new applications can benefit from NIR spectral analysis if the systems can be sufficiently miniaturized for mobile use and made available at a low cost.
For this reason, the Fraunhofer Institute for Photonic Microsystems IPMS is developing ultra-small analysis devices that can even be integrated into handhelds, tablets or, in perspective, smartphones. The use of micro-electromechanical systems (MEMS) enables very compact systems that can be manufactured cost-effectively in large quantities.
Despite its small size, the quality of the measurements is competitive for many important applications. The obtained data is analyzed chemometrically on site or online and specific features are extracted from it.
This makes it possible, for example, to make direct statements about the ripeness and freshness of food. Other applications such as checking correct mixing ratios in food processing, rapid inbound and outbound goods checks or selection in recycling or reuse processes can also be served.
Current research at Fraunhofer IPMS combines a simple technology for the MEMS component with a large addressable spectral range of the system and a high degree of modularity.
The core of the system is a MEMS scanning mirror, which deflects the incident collimated light rays onto a grid mounted in the system. A selection of different spectral diffraction gratings is possible, which can be optimized and used for specific applications.
Presentation of spectral analysis at the Analytica fair in Munich
The current demonstrator, also on display at the Fraunhofer IPMS booth at the Analytica fair in Munich from June 21 to 24, focuses on the proven spectral range of 950 nm to 1900 nm with a spectral resolution of 10 nm.
Currently, the system achieves a build volume of about 2 cm³. However, further miniaturization is possible.
The measurements are performed in typical setups, depending on the sample properties, for example in transmission for liquid media or sufficiently transparent solids or in diffuse reflection for less transparent samples with sufficient scattering cross-section.
The optical coupling of the spectrometer is possible as free-beam optics or via coupled fibres. In the demonstrator, the detection of white powders is shown.
This can be salt, sugar, starch or flour, but many substances that are visually similar can be reliably detected and assigned.
Visitors to the Analytica fair in Munich can find Fraunhofer IPMS at booth #A3-227.