SBIR-STTR Award

Polarization Metasurface Detection Device for Food Safety The ongoing effort in food safety diagnostics is in constant need of tests, which are more deployable (i.e. lower-cost and more compact), with the utmost accuracy. Metasurface-based optics present an opportunity for high-performance optical fixtures at reduced cost and size to conventional optics. A single metasurface is capable of multiple simultaneous functions (i.e. a lens, diffraction grating, and polarizer). Further, two such lenses can be superimposed in a single surface. Due to only requiring a thickness of less than one micron, metasurface-based optics provide dramatic reductions in size and weight compared with traditional refractive or reflective optics - from 300 grams to under 2 grams, typically. The only material necessities for a metasurface are that it is transparent and possesses a significant difference in index of refraction to that of the external optical medium, often air or an aqueous solution. This allows the opportunity for producing a metasurface from a low cost (i.e. disposable) material such as a patterned Si on silica. As a result, metasurface optics technology offers an opportunity to surpass the performance of traditional optics at reduced cost while maintaining a more compact footprint. The field of optical metasurface biosensing has only very recently been explored. To date, the metasurface "bind and detect" assay is primarily based on a phase shift of transmitted light. This modality, while sensitive, suffers from a noise floor, which is dominated by vibrational noise. For this reason, an investigation into producing a disposable (i.e. low-cost), high-performance metasurface, which uses a change in polarization of light instead of a phase shift, would greatly reduce the noise floor of an optical metasurface assay because the polarization of light is much more independent from the vibration of the medium in comparison to phase. Reducing this noise floor would create an opportunity for a highly sensitive washless "bind and detect" assay with rapid testing (within minutes), high-throughput multiplexing, and portability to ports of entry and food processing plants. To this end, Nanohmics, will fabricate a metasurface wave plate surface, which operates as a high-efficiency infrared polarizer. Forming the base of a 96-well plate, this metasurface will be functionalized through silanization with a unique antibody in each well. Upon binding with an anitibody a pathogen will induce a persistent polarization change in the transmitted light. This will facilitate rapid and deployable sensing of pathogens of interest to food safety with multiplexed delineation.

Public Health Relevance Statement:
Polarization Metasurface Detection Device for Food Safety Narrative The ongoing effort in food safety diagnostics is in constant need of tests, which are more deployable (i.e. lower-cost and more compact), with the utmost accuracy. Metasurface-based optics offer an opportunity to meet these goals. Nanohmics seeks to develop a polarization metasurface-based biosensor, which is robust against vibrational and background noise, in order to develop a highly sensitive washless "bind and detect" assay with rapid testing (within minutes), high-throughput multiplexing, and portability to ports of entry and food processing plants.

Project Terms:

For farm-to-fork testing for the entire food supply chain, Nanohmics proposes to develop its metasurface-based MetaDotTM bind-and-detect biosensor for portable, low-cost, rapid, highly sensitive multiplex screening of foodborne pathogens. Nanohmics' MetaDot optical reader is designed to measure pathogen binding on a custom optical metasurface test chip coated with an array of bioreceptor regions (dots), each functionalized for direct covalent receptor binding using aminated antibodies or DNA aptamers. MetaDot will provide easy and highly accurate multiplex detection, identification, and quantification of foodborne pathogens. Each single-use functionalized biosensor chip is mounted in a custom cassette for precise insertion into the MetaDot reader. When the biosensor chip is exposed to the rinsate or solution under test, the reader probes the 36 dot regions simultaneously using polarized monochromatic light reflected by each dot as a function of the density of local pathogen binding. Phase II will demonstrate a simultaneous test for less than $3 for 36 dots, enough to cover the 31 major identified foodborne pathogens. The Phase II program will develop and test the MetaDot prototype: Research Aim 1 addresses low-cost multiplex functionalization using a microspotting robot. Research Aim 2 develops the reader. Research Aim 3 concentrates on reducing the cost of metasurface microfabrication. Phase I has already demonstrated a scalable fabrication process that can reduce metasurface cost to dollars per chip. MetaDot's active probing architecture and transparent substrate avoids the photon-starved, low-SNR operation of fluorescence and other detection technologies. Instead, MetaDot provides high signal-to-noise ratio (SNR) and highly accurate and repeatable measurements. Existing pathogen test systems are often costly, non-portable, or require operation by a laboratory technician. In contrast to commercial surface plasmon resonance (SPR) detection, the proposed metasurface has many times more microscopic surface area, increasing overlap between pathogens and the evanescent electric-field of the reflected light. Compared to existing SPR sensors, the MetaDot system reduces cost and size by two to three orders of magnitude. Unlike optical techniques based on external labeling, resonance shifting in the MetaDot metasurface operates as a reporter of the pathogen binding phenomena in a label-free fashion and enables transduction of the capturing event directly as a shift in the polarization of the reflected light. The MetaDot reflection probe geometry separates the optical path from the test solution, minimizing scatter and enabling extremely low noise and high sensitivity. The MetaDot reader is designed to use common commercial off-the-shelf (COTS) optics and electronics and will be easy to use and inexpensive to manufacture. MetaDot can be extended to detect a wider range of pathogens for point-of-care (PoC) applications as diverse as first-aid wound infection diagnosis, on-site dental pathogen assessment, and screening for infectious diseases at ports of entry.

Public Health Relevance Statement:
Project Narrative The lack of ubiquitous, low-cost food safety screening is costly in terms of both commerce and human health. Low- cost, rapid (within minutes), high-throughput, highly sensitive testing with portability to ports of entry and food processing plants could have great value to the FDA and USDA Food Safety Inspection Service (FSIS) and the whole food industry. To address food testing challenges, Nanohmics, Inc. is developing the MetaDotTM bind-and-detect biosensor for portable, low-cost, rapid, and highly sensitive multiplex food safety screening, to provide easy and highly accurate detection, identification, and quantification of foodborne pathogens.

Project Terms: