Terahertz waves have unique specifications that make them very attractive for non-invasive, label-free biosensing. This is because many organic compounds have unique responses to the electromagnetic waves at terahertz frequencies. In addition, terahertz waves can penetrate through many optically-opaque environments as well as most of the packaging materials such as plastic, paper, etc. These great potentials make terahertz imaging/spectroscopy systems an excellent platform for high-sensitivity, high-throughput, and non-destructive detection of aflatoxins, which can grow in various agricultural food products and cause various chronic health problems if consumed, including liver cancer. Aflatoxins have unique spectral characteristics at terahertz frequencies, however the use of terahertz waves for high-throughput and high-sensitivity aflatoxin detection in food products did not seem practical before because of the low sensitivity of conventional terahertz scanners, which suffer from a trade-off between the signal-to-noise ratio (SNR) and the measurement time. For instance, to achieve a sufficiently sensitive measurement to detect the maximum allowed aflatoxin contamination level regulated by the Food and Drug Administration (FDA) with conventional terahertz scanners, more than thousand measurements should be taken on the same sample to reduce the noise of the acquired data, which increases the measurement time significantly. In addition, most of the terahertz spectroscopy measurements should be performed in very meticulous ways, which require specific sample preparation recipes that are not appropriate for field settings. The proposed research addresses these limitations of conventional terahertz scanning systems and offers a high-throughput, non-destructive, and highly-sensitive aflatoxin scanner that does not require a skilled user to operate. The key innovations that enable such a high-performance aflatoxin scanner are: (1) the use of a breakthrough plasmonic terahertz source and detector technology that offers several orders of magnitude higher SNR levels compared to those offered by conventional terahertz devices, (2) the use of an advanced data analysis algorithm that is capable of direct calculation of aflatoxin concentration regardless of the type and shape of the sample under test. As a result, the proposed terahertz scanner offers an excellent regulatory tool for high-throughput, non-destructive, non-contact detection of aflatoxins in nuts and processed nut products, minimizing regulatory non-compliance risks and providing high-quality products to the public. By the end of the Phase I, a thorough experimental analysis will be completed on aflatoxin tablets and aflatoxin- contaminated nuts with a single-pixel terahertz scanner prototype to assess the sensitivity and specificity of the proposed scanner. In Phase II, the aflatoxin scan rate will be boosted by using focal plane detector arrays and the use of the developed multi-pixel scanner for detection of aflatoxins will be extended to a wider range of agricultural food products, while developing a prototype that can be used in realistic field/packaging/distribution settings.

Public Health Relevance

High-sensitivity and high-throughput detection of carcinogen aflatoxins in nuts and processed nut products would have a significant impact on human health. To achieve this goal, we propose an advanced terahertz scanner that can inspect nuts and processed nut products and detect aflatoxin contamination with concentrations lower than the maximum allowed levels by FDA in a non- invasive and contactless scheme. The key innovations enabling such a high-performance aflatoxin scanner are the use of plasmonic terahertz sources and detectors, which offer significantly larger signal-to-noise ratios compared to conventional systems, and a novel data analysis algorithm, which directly calculates aflatoxin concentration regardless of the type and shape of the sample under test.

National Institute of Health (NIH)
Food and Drug Administration (FDA)
Small Business Innovation Research Grants (SBIR) - Phase I (R43)
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Special Emphasis Panel (ZRG1)
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Brown, Tashea
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Lookin, Inc.
Los Angeles
United States
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