Recent developments in handheld and portable optosensing-a review.

Recent developments in portable and handheld opto-chemical analytical instrumentation over the last decade (2000-2010) are reviewed. First, the characteristics of typical portable/handheld instrumentation are discussed from different points of view: in situ operation, low energy consumption, ease of use, and self-contained devices. These advancements have improved or hastened improvements in the development of miniaturized optoelectronic and optical components, mainly solid-state devices such as different types of semiconductor lasers, light-emitting diodes, and photodiodes. A brief review of advances in these components is also presented. The numerous examples of portable instrumentation presented have been classified according to direct-recognition and reagent-based sensing, and within these, by absorption and emission-based systems. The conclusion discusses some key trends and future perspectives for this technology.