Examining the Application of Terahertz Metamaterials for Food Safety Testing

A recent study examined a new way that can improve agricultural product testing. This study, which was led by Jianfeng Qiu of Shandong First Medical University & Shandong Academy of Medical Sciences, examined the potential benefit of using terahertz metamaterials (THz-MM) in food safety inspections (1). THz-MM can be considered analogous to SERS (surface-enhanced Raman spectroscopy) in Raman, as the metamaterials are used to enhance the THz spectral signals. THz-MM technology is viewed as a more efficient, reliable, and non-invasive technology (1). This review article highlighted the latest advancements in THz-MM technology, how it’s being applied in agriculture, and where this technology is heading in the future.

Workers examining and sorting fresh carrots on a conveyor system in a processing facility during daylight hours | Image Credit: © Vital - stock.adobe.com

Currently, the food safety industry is handling numerous challenges simultaneously. Agricultural products face risks of contamination from pesticide residues, pollutants, and improper storage. Traditional methods for testing, such as high-performance liquid chromatography (HPLC), while highly accurate, often require time-intensive sample preparation, skilled personnel, and specialized laboratory equipment (2). As consumer demand for rapid food safety testing grows, researchers have turned their attention to alternative technologies that can provide quick, sensitive, and non-destructive analyses (1–3).

In this study, the researchers highlighted the utility of THz-MM in this space. THz-MM are defined as artificially engineered structures designed to enhance THz electromagnetic waves (1). What makes these materials unique is that they can be tailored to operate in the THz frequency range (0.1–10 THz), which lies between microwave and infrared (1). This region is particularly important for food safety testing because many organic molecules exhibit unique “fingerprints” at terahertz frequencies, corresponding to their vibrational and rotational energy levels (1). By exploiting these molecular signatures, THz metamaterials can identify contaminants or residues in food products without damaging them (1).

THz-MM have been built with a wide range of materials. The researchers discussed in their review that graphene, vanadium dioxide, carbon nanotubes, and gold nanoparticles have been used to develop THz-MM (1). Each material offers specific advantages in terms of conductivity, tunability, and sensitivity. For example, metals such as gold, silver, copper, and aluminum are widely used because of their electrical conductivity and compatibility with microfluidic systems (1).

After discussing how THz-MM are built, the researchers spotlighted a few new innovations in this space. First, the researchers highlight how optimizing the structural topology is improving detection sensitivity (1). By fine-tuning the geometry and arrangement of metamaterial structures, scientists can significantly improve the performance of THz sensors, allowing them to detect even trace amounts of harmful substances in agricultural products (1). This type of precision is important, especially in applications such as monitoring pesticide residues, which has taken on increased importance to protect human health (1,2).

Another innovation of THz-MM technology is how easy they are to produce. Unlike mid-infrared or visible-light-based metamaterials, which require extremely precise fabrication techniques, THz metamaterials do not require this level of precision to make (1). Their high penetration capabilities also allow for the inspection of packaged foods, reducing the need to open or alter products during testing (1). Therefore, this technology highly attractive for real-world applications in food supply chains and market supervision.

However, the researchers acknowledge that because this technology is new, there are some limitations that need to be addressed before it can progress further. First, there are cost considerations, as THz-MM are expensive to make. Second, large-scale fabrication remains a challenge. And finally, integrating THz-MM into portable devices remain challenges for researchers (1). The researchers emphasize that future research should focus on improving material design, developing more efficient structural models, and exploring novel fabrication techniques to make the technology more accessible and commercially viable (1).

Because more work is being conducted in this space, it is expected that the potential applications of THz-MM will expand rapidly. Some potential applications of THz-MM include rapid detection of chemical pollutants to quality assessment of agricultural products (1) By offering a non-invasive, highly sensitive, and easy-to-operate alternative to traditional detection methods, THz-MM-based spectroscopy may soon become a cornerstone in modern agricultural testing (1).

Therefore, the researchers conclude that THz-MM, and the progress developing them the past five years, will play role in safeguarding global food supplies in the future.

References

1. Cong, M.; Zhang, Z.; Song, W.; Qiu, J. Food safety application of Terahertz spectroscopy based on metamaterials: A review. J. Food Comp. Anal. 2025, 139, 107034. DOI: 10.1016/j.ifca.2024.107034
2. Workman, Jr., J. Advanced Spectroscopy Uncovers Hidden Pesticide Contaminants with Precision. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/advanced-spectroscopy-uncovers-hidden-pesticide-contaminants-with-precision (accessed 2025-08-19).
3. Wetzel, W. How the Advancement of Soil Spectroscopy is Improving Agriculture in The Gambia. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/how-the-advancement-of-soil-spectroscopy-is-improving-agriculture-in-the-gambia (accessed 2025-08-19).