The exploitation of microdroplets produced within microfluidic environments has recently emerged as a new and exciting technological platform for applications within the chemical and biological sciences. Interest in microfluidic systems has been stimulated by a range of fundamental features that accompany system miniaturization. Such features include the ability to process and handle small volumes of fluid, improved analytical performance when compared to macroscale analogues, reduced instrumental footprints, low unit cost, facile integration of functional components and the exploitation of atypical fluid dynamics to control molecules in both time and space. Moreover, microfluidic systems that generate and utilize a stream of sub-nanolitre droplets dispersed within an immiscible continuous phase have the added advantage of allowing ultra-high throughput experimentation and being able to mimic conditions similar to that of a single cell (in terms of volume, pH, and salt concentration) thereby compartmentalizing biological and chemical reactions. This review provides an overview of methods for generating, controlling and manipulating droplets. Furthermore, we discuss key fields of use in which such systems may make a significant impact, with particular emphasis on novel applications in the biological and physical sciences.

This tutorial review will introduce and explore the fundamental aspects of nanopore (bio)sensing, fabrication, modification, and the emerging technologies and applications that both intrigue and inspire those working in and around the field. Although nanopores can be classified into two categories, solid-state and biological, they are essentially two sides of the same coin. For instance, both garner popularity due to their ability to confine analytes of interest to a nanoscale volume. Due to the vast diversity of nanopore platforms and applications, no single review can cover the entire landscape of published work in the field. Therefore, in this article focus will be placed on recent advancements and developments taking place in the field of solid-state nanopores. It should be stated that the intention of this tutorial review is not to cite all articles relating to solid-state nanopores, but rather to highlight recent, select developments that will hopefully benefit the new and seasoned scientist alike. Initially we begin with the fundamentals of solid-state nanopore sensing. Then the spotlight is shone on the sophisticated fabrication methods that have their origins in the semiconductor industry. One inherent advantage of solid-state nanopores is in the ease of functionalizing the surface with a range of molecules carrying functional groups. Therefore, an entire section is devoted to highlighting various chemical and bio-molecular modifications and explores how these permit the development of novel sensors with specific targets and functions. The review is completed with a discussion on novel detection strategies using nanopores. Although the most popular mode of nanopore sensing is based upon what has come to be known as ionic-current blockade sensing, there is a vast, growing literature based around exploring alternative detection techniques to further expand on the versatility of the sensors. Such techniques include optical, electronic, and force based methods. It is perhaps fair to say that these new frontiers have caused further excitement within the sensing community.

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We demonstrate that single cells can be controllably compartmentalized within aqueous microdroplets; using such an approach we perform high-throughput screening by detecting the expression of a fluorescent protein in individual cells with simultaneous measurement of droplet size and cell occupancy.