Compared to analytical labs requiring large instruments and skilled users, micro/nano-sensors show great promise as convenient economic tools for specific detection based on bio-physico-chemical interactions of target compounds on sensitive coatings, and for monitoring dynamically the characteristics of fluids or biofilms, as influenced by new compounds. We present an overview of the existing microsensors, and their principles, and describe microsensors that can be developed for fast evaluation of efficiency and toxicity of innovative therapeutic nanostructures. We also describe their key applications, and discuss the analytical techniques employed. Integrative technologies involving multisensor set - akin to an electronic nose or tongue, or those involving a separator step prior to the transducer itself are also presented. Specifically, we discuss micro/nano-fluidics with relevance to particule-flow management, in the field of microsensors towards therapeutics. Ex vivo and in vivo approaches are considered, both in-line or remote controlled, with various analytes collected using invasive or non-invasive techniques.