Microsensors on the Fly

Abstract

Optically driven microresonators freely floating in liquids, embedded into transparent solid media, or even taken up by life cells, can be exploited as optical microsensors, which yield precise information on the immediate local condition of their respective environment. Besides plain physical information, such as on local refractive indices, mechanical stress, and mixture ratios in composite materials, the sensors may be applied as chemical and even bio‐sensors for the specific targeting of biochemical binding reactions if accordingly functionalized. Sensitivity can be further improved by driving the sensors above the lasing threshold, thereby increasing signal intensity and optical resolution at the same time. In this article, we introduce the optical principles, present useful implementations, and illustrate feasibility of this still novel approach to optical sensing by a number of diverse examples.