Chip-scale sensor for spectroscopic metrology

TL;DR

This paper introduces a miniaturized, integrated NIR spectrometer capable of high-resolution, wide-bandwidth measurements with performance comparable to large benchtop devices, enabling precise spectroscopic analysis in compact form.

Contribution

The paper presents a fully packaged, chip-scale reconstructive spectrometer with record-breaking bandwidth-to-resolution ratio and high accuracy in substance classification and concentration measurement.

Findings

Achieves <8 pm resolution over 520 nm bandwidth

Classifies solid substances with nearly 100% accuracy

Detects glucose concentration as low as 0.1%

Abstract

Miniaturized spectrometers hold great promise for in situ, in vitro, and even in vivo sensing applications. However, their size reduction imposes vital performance constraints in meeting the rigorous demands of spectroscopy, including fine resolution, high accuracy, and ultra-wide observation window. The prevailing view in the community holds that miniaturized spectrometers are most suitable for the coarse identification of signature peaks. In this paper, we present an integrated reconstructive spectrometer that enables near-infrared (NIR) spectroscopic metrology, and demonstrate a fully packaged sensor with auxiliary electronics. Such a sensor operates over a 520 nm bandwidth together with a resolution of less than 8 pm, which translates into a record-breaking bandwidth-to-resolution ratio of over 65,000. The classification of different types of solid substances and the concentration measurement of aqueous and organic solutions are performed, all achieving approximately 100% accuracy. Notably, the detection limit of our sensor matches that of the commercial benchtop counterparts, which is as low as 0.1% (i.e. 100 mg/dL) for identifying the concentration of glucose solution.