Spectral sensing breakthrough
Researchers at Aalto University in Finland have created a breakthrough in spectral sensing through combining miniaturised hardware and intelligent algorithms, creating a tool that is compact, cost-effective, and capable of solving real-world problems in applications such as healthcare, food safety and autonomous driving.
Currently, spectral sensing is a powerful technique that identifies materials by analysing how they interact with the light, and is particularly beneficial for disease diagnosis, counterfeit drug detection or spoiled food warnings.
However, this technology traditionally requires bulky, expensive systems confined to laboratories and industrial applications. The miniaturised tool created by the researchers has the possibility to fit inside a smartphone or a wearable device.
“It’s similar to how artists train their eyes to distinguish hundreds of subtle colours,” explained Zhipei Sun, professor and lead researcher. “Our device is ‘trained’ to recognise complex light signatures that are imperceptible to the human eye, achieving a level of precision comparable to the bulky sensors typically found in laboratories.”
This sensor achieves spectral differentiation through its electrical responses to light which makes it suitable for being integrated into small devices. The researchers demonstrated its capability to identify materials directly from their luminescence as they tested it on organic dyes, metals, semiconductors and dielectrics.
“Our innovative spectral sensing approach simplifies challenges in material identification and composition analysis,” added Xiaoqi Cui, the study’s lead author, who recently defended his doctoral thesis at Aalto University.
The innovation combines tunable optoelectronic interfaces with advanced algorithms, unlocking new possibilities for applications in integrated photonics and beyond.
During its training, the device was exposed to a wide range of light colours so it could learn and generate unique electrical fingerprints for each light type. The fingerprints are then decoded by an intelligent algorithm which means the sensor can accurately identify materials and analyse their properties based on how they interact with light.
The device measures 5 micrometres by 5 micrometres - 200 times smaller than the cross-section of a human hair, for reference - and can achieve a peak wavelength identification accuracy of ~0.2 nanometres, enabling it to distinguish thousands of colours.
At the core of the sensor is a designed optoelectronic interface that allows precise control of electrical flow through voltage adjustments.
“This work is a major step forward in bringing spectroscopic identification to everyone’s fingertips,” said Fedor Nigmatulin, doctoral researcher and joint first author. “By integrating this ultra-compact hardware with intelligent algorithms, we’ve taken a significant step toward miniature, portable spectrometers that could one day transform consumer electronics.”
The hope is that this miniaturised sensor will bring the power of advanced spectroscopy into devices we use every day and in doing so, revolutionise the sector.