Researchers at the University of Cambridge and GlitterinTech, a startup founded by the same research group, have developed a new type of optical spectrometer that combines high precision with a small size and low cost.

Only a few centimeters in diameter, the device can be integrated into portable electronics and wearable health technology. Its potential applications include real-time monitoring of health markers, material identification, and the detection of changes in chemical composition.

What is an optical spectrometer?

Optical spectrometers analyze light to reveal information about the materials it interacts with. They are widely used in medicine, manufacturing, chemical testing, and environmental research.

However, miniaturizing these instruments has traditionally required compromises. Compact spectrometers are often better suited to identifying materials than to making highly precise measurements because of their limited measurement range, lower resolution, and reduced accuracy.

The researchers believe their new design could overcome many of these limitations. Known as a convolution spectrometer, the device uses a mathematical principle called the convolution theorem to analyze light in a fundamentally different way.

According to the researchers, the approach offers advantages over existing spectrometer designs in areas including light dispersion, Fourier transformation, and computational reconstruction.

How the convolution spectrometer works

Traditional spectrometers typically separate incoming light into its component wavelengths or use complex calculations to reconstruct the spectrum. The new device instead performs a mathematical operation called convolution directly on the incident light.

To achieve this, the researchers placed optical components in sequence so that they repeated their spectral responses. These components may include unbalanced Mach-Zehnder interferometers or microring resonators.

By adjusting the components proportionally, the system can shift its response to different wavelengths in a controlled, linear way. A fast Fourier transform then recovers the optical spectrum accurately.

“The key insight was to go back to the mathematics and ask whether there is a fundamentally clean way to obtain spectra,” said Dr. Chunhui Yao, lead author of the study. “By using the convolution theorem directly in the optical domain, we avoid many of the limitations that have hindered compact spectrometers. This provides high accuracy, strong noise immunity, and very low computational overhead, all in a compact, low-cost system.”

Wide wavelength range and subsecond measurements

The researchers built the spectrometer using a silicon nitride photonic platform and integrated it with onboard electronics. It operates across a near-infrared wavelength range of 1,200 to 1,700 nanometers and can collect and process measurements in less than one second.

The system’s measurement capabilities can also be expanded without major hardware changes. Because it uses a repeating optical pattern, the spectral bandwidth could theoretically be extended almost indefinitely. Adding more optical components in sequence can also significantly increase resolution.

A $10 sensor for food testing, medicine, and quality control

To test the device beyond theoretical measurements, the researchers analyzed a range of materials and substances. The results demonstrated potential applications that typically depend on large, expensive laboratory equipment.

In the reported tests, the spectrometer achieved a 100% classification success rate when identifying plastics, pharmaceuticals, coffee, flour, and tea. It also measured the concentrations of water-based and organic solutions with an accuracy of approximately 0.01%, outperforming commercial benchtop spectrometers in those experiments.

Could it enable needle-free blood sugar monitoring?

The healthcare demonstration was particularly promising. Under conditions designed to reflect real-life physiological environments, the device accurately measured several human biomarkers, including skin moisture, blood alcohol, blood lactate, and blood sugar.

The researchers also demonstrated long-term, non-invasive glucose tracking in one participant. More testing is needed before the technology can become a practical medical product, but the findings suggest that it may eventually help monitor blood sugar without repeated skin pricks.

“These biomedical demonstrations are particularly exciting,” said Professor Qixiang Cheng, who led the project. “What sets this work apart is its technical readiness, as well as its performance in the laboratory. Dr. Chunhui Yao’s contributions were critical in translating the mathematical concepts into a fully packaged and robust system that operates reliably under extreme temperatures and real-world conditions. That combination opens the door to practical applications.”

The sensor also resisted temperature changes, continuing to operate reliably between -20°C and 80°C. This unusually wide operating range could be valuable for wearable devices, factory equipment, and outdoor sensors.

Why the simple design matters

The spectrometer’s advantages extend beyond its accuracy, size, and cost. Its internal design also reduces the computational power needed to analyze incoming light.

Many compact spectrometers depend on complex calibration procedures and demanding algorithms to reconstruct spectral information. These approaches can become unreliable when measurements are noisy and may require substantial processing resources.

The Cambridge team’s convolution-based approach avoids much of this complexity. Because the measurements follow linear mathematical relationships, the system can recover spectra quickly and consistently while using relatively little computational power.

“This is a beautiful example of how elegant engineering can unlock real impact,” said Professor Richard Penty, who contributed to the design and integration of the photonic system. “This architecture is simple, scalable, and manufacturable while delivering accuracy comparable to or exceeding much larger instruments. Dr. Chunhui Yao played a central role in putting together the photonic design, system integration, and experimental validation that made this possible.”

The relatively simple structure could also support large-scale manufacturing, potentially bringing advanced optical measurements to devices that would otherwise be too bulky or expensive for traditional spectrometers.

From laboratory instruments to everyday sensors

The researchers envision a future in which precise optical sensing becomes a routine feature of everyday technology rather than being limited primarily to specialized laboratories.

In manufacturing, inexpensive spectrometers could be installed throughout a facility to continuously check material composition and product quality. Similar sensors could help monitor food freshness, identify substances, and analyze environmental conditions on a much larger scale than is currently practical.

Compact optical sensors could also have significant medical applications. Future wearables may measure hydration, detect signs of alcohol intoxication, track biomarkers related to physical fitness, or continuously monitor blood sugar in people managing diabetes.

“Our vision is to make spectroscopic measurements as ubiquitous as temperature and motion sensing,” added Professor Qixiang Cheng. “This study shows that high-quality spectral information doesn’t have to be limited to the laboratory; it can be integrated directly into the technology people use every day.”

As photonic technologies become smaller and more sophisticated, convolution spectrometers offer a promising example of how mathematical insight and practical engineering can make advanced scientific instruments simpler, cheaper, and more accessible.

By combining high precision with a device that costs about $10, the researchers have created a potential foundation for a new generation of smart sensors capable of detecting chemical changes in materials and around the human body.