A smartphone-inspired spectrometer platform, built with low-cost plastic materials instead of glass, could make spectral imaging more accessible across the scientific, industrial, and consumer domains. The spectrometer spans the visible to SWIR range and is fabricated using mass-producible, non-lithographic methods. These properties could make it suitable for in-home health care monitoring, food quality testing, agricultural sensing, and many other applications that require affordable, broadband sensing capabilities. The spectrometer design is the result of a collaboration among researchers at the University of Cambridge, Zhejiang University, Zhejiang Sci-Tech University, and Nanyang Technological University, with backgrounds in materials science, optical engineering, and signal processing. Birefringence of plastic products in the lab. (Scale bar: 1 cm). Courtesy of Science Advances (2025). DOI: 10.1126/sciadv.adu4225. Plastic optical components are used in smartphone cameras to achieve high performance in an ultracompact format. Inspired by this approach, the research team took a similar path, using transparent shape memory epoxies to stress-engineer optical dispersive elements made from plastic. The epoxy used for the spectrometer, bisphenol A epoxy, is highly transparent across the visible to SWIR range. Shape memory epoxies can be mechanically stretched at elevated temperatures to program precise, stable stress distributions into the material. These stresses create birefringence, an optical effect where light is split according to its wavelength. Through temperature-controlled mechanical stretching, the team was able to stress-engineer the epoxy and tailor its optical properties. Shape memory epoxies provide superior stress storage compared to other plastic materials, which enables a wide range of spectral encoding through stress engineering. “By shaping the internal stress within the polymer, we are able to engineer spectral behavior with high repeatability and tunability, something that’s incredibly difficult to achieve with conventional optics,” professor Gongyuan Zhang said. The resulting films act as spectral filters, encoding information that can be read by standard CMOS image sensors and reconstructed via algorithms. The researchers demonstrated that the planar, stress-engineered epoxy films can be used to form a spectrometer device when they are integrated with a commercial CMOS image sensor and a spectral reconstruction algorithm is used for computational processing of the pixel outputs. The use of large-scale stretched epoxy films as filters significantly enhances the yield of the spectrometer. The team realized miniaturized spectrometers with broad coverage across both the visible (400-800 nm) and NIR (800-1600 nm) ranges. The epoxy film layer also enables the spectrometer to serve as a line-scanning device for spectral imaging on 2D images, facilitating the acquisition of corresponding spectral data cubes, and demonstrating the spectrometer’s potential as a portable tool for hyperspectral imaging. The stress-engineered films can be fabricated in a single step, without the need for lithography or expensive nanofabrication, making the spectrometers suitable for mass production and integration into consumer electronics like mobile phones and wearable technologies. “We’ve shown that you can use programmable plastics to cover a much broader range of the spectrum than typical miniaturized systems — right into the SWIR,” professor Zongyin Yang said. “That’s really important for applications like agricultural monitoring, mineral exploration, and medical diagnostics.” The new spectrometer design could be used to detect pollutants, verify the authenticity of drugs, monitor blood sugar noninvasively, and even to sort recyclable materials in real-time. By eliminating the trade-offs between size, cost, and spectral range, the spectrometer could help advance research in computational photonics and sustainable sensing technologies. “This work shows how mechanical design principles can be used to reshape photonic functionality,” professor Tawfique Hasan said. “By embedding stress into transparent polymers, we have created a new class of dispersive optics that are not only lightweight and scalable but also adaptable across a wide spectral range. This level of flexibility is very difficult to achieve with traditional optics relying on static, lithographically defined structures.” As the team continues to refine the design and explore commercial pathways, the stress-engineered, plastic spectrometer could become a building block for the next generation of intelligent, compact sensors embedded in devices for everyday use. The research was published in Science Advances (www.doi.org/10.1126/sciadv.adu4225).
