Scientists invent near-infrared sensors: easy to manufacture with dimensions comparable to mobile phone sensors

A research team from Eindhoven University of Technology has recently developed a brand new near-infrared sensor, which is easy to manufacture, has the same size as sensors in smartphones, and can be immediately used for industrial process monitoring and agriculture. This breakthrough has just been published in Nature Communications.

The human eye is a magical sensor. By using three different types of photosensitive cone cells to convert visible light into signals of different colors, the eyes provide basic information about the world around us. "When our brain puts these signals together, it predicts the meaning of these signals based on our experience. For example, red strawberries are sweet, but green strawberries are not," explained Kaylee Hakkel, co first author of the study and doctoral researcher in the Photonics and Semiconductor Nanophysics groups of the Department of Applied Physics.

Although human eyes are impressive, they are not the most powerful in nature. Hakkel said, "The eyes of praying mantis shrimp have 16 different types of cells that are sensitive to ultraviolet, visible, and near-infrared (NIR) light. Measuring infrared spectra is the most interesting for industrial and agricultural applications, but there is a major issue - current near-infrared spectrometers are too large and expensive.".

Hakkel and her collaborators solved this problem by developing a near-infrared sensor suitable for small chips. And just like the eyes of praying mantis shrimp, it has 16 different sensors - but they are all sensitive to near-infrared radiation. She said, "The miniaturization of sensors while maintaining low cost is a major challenge. Therefore, we have designed a new wafer level manufacturing process to achieve this goal.".

She continued, "Its cost is very low because we can produce multiple sensors simultaneously, and it is ready to be used in real-world applications now. The sensor chip is very small and can even be embedded in future smartphones.".

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