1. Introduction

Optofluidics defines a wide research field that is characterized by the synergic combination of optics and microfluidics; hence, the term can be applied either when light senses or modifies a fluid or when a fluid is used to define or tune the properties of a photonic device (e.g., laser activated fluids, liquid lenses or microfluidic microscope) [1], [2]. In biophotonic applications, the combination of microfluidics and optics is typically exploited to further increase the miniaturization of the devices toward an integrated optofluidic platform [3]. Such a platform would benefit from both aspects previously mentioned in the definition of optofluidics; on the one hand, small amounts of fluid can provide unprecedented reconfigurability of the photonic devices; on the other hand, the very high sensitivity of optical detection methods can provide relevant measurements even on small amounts of biological fluid samples (nano/picoliters), down to single molecule detection [4], [5]. Particular attention is dedicated to the integration of different functionalities on a single substrate to obtain a lab-on-chip microsystem that can address biochemical and biomedical assays in a cost-effective, miniaturized, and automated way. Here, we review a selection of results reported in 2011, by classifying them into four main areas of research: 1) lens-free optofluidic microscopes (OFMs); 2) fluidic tuning of photonic devices; 3) on-chip optofluidic sensors; 4) optofluidic micromanipulation of biosamples.