Miniaturisation of Raman spectroscopy systems: from benchtop to backpocket.

The global portable spectroscopy market is rapidly expanding, with optical technologies composing the greatest market share. One prominent light-based technology is Raman spectroscopy, which confers benefits in terms of high selectivity and thus untargeted detection and multiplexing capabilities. Alongside this, plasmon-enhanced Raman technologies can provide ultra-low, even single molecule, detection. In this article, we analyse the current trends in the miniaturisation of Raman systems, including constituent components, evaluating current market needs, and providing a prospective on likely developments within Raman spectroscopy systems in the coming years. In particular, the progress from handheld Raman systems, which have surged in popularity since 2010 in a plethora of application spaces, to fully integrated on-chip Raman devices, is surveyed. Such palm-sized devices offer potentially easy integration into, for example, consumer white goods at home, and lightweight drone systems, and thus could transform the portable sensing landscape.