Miniature and multi-spectral spectrometers in consumer goods and wearables

Abstract

In the past twenty years optical spectrometers have shrunk dramatically in size, giving us successively laboratoryportable, toaster-sized, instruments; cordless-drill-sized portable instruments for use in the field; and onto spectrometers the size of a computer mouse or deck of cards. The latest development in portable spectroscopy is the availability of very low-cost multispectral sensors, the size of computer chips, leading to the possibility of embedding them into consumer goods, including personal health monitoring, and eventually into medical products. The width of absorption bands in the visible and near-infrared regions for condensed phase samples imply that an instrument with a small number of resolution elements will be able to perform routine analyses, and that spectral range is a more important parameter than spectral resolution. Multispectral sensors can now be incorporated into 'fitness' products like smart watches and sports watches, and as photonic miniaturization increases, into 'wearables' like smart rings providing the user with health information. Multispectral devices can be produced in volume via semiconductor and optical coating techniques, at very low cost -less than $10 each. Silicon photonics and photonic integrated circuits (PICs), produced en masse using semiconductor manufacturing techniques, are the ideal next step. This paper surveys the field and highlights some 'smart' consumer device possibilities from toothbrushes to toilets.

Emerging technologies for miniature spectrometers and multispectral sensors

“…The use of optical filters 54 in small spectrometers has been comprehensively reviewed. 55 Here, we are mainly concerned with LVFs and discrete or patterned filters, used with array detectors to provide compact spectroscopic devices with no moving parts. It should be noted that this filter technology is very mature, coming from a combination of optical telecommunications and digital camera production: The key technology for digital color cameras is the use of a Bayer filter pattern (two green, one red and one blue in a grid of four) on the sensor itself.…”