This book is the second edition of the one originally published in 2016, which focused on state-of-the-art microfluidic research in medical and biological applications. Similar to the first edition, beginners in the field —undergraduates, engineers, biologists, medical and pharmaceutical researchers—will easily learn to understand microfluidic-based medical and biological applications. Because a wide range of topics is summarized here, it also helps experts to learn more about fields outside their own specialties. In this second edition, significant revisions have been made to chapters covering technologies that have seen major advancements, such as acoustofluidics, protein crystallography, organ-on-a-chip systems, nanopore sensing, and paper-based microfluidics. In addition, the chapters on cancer diagnosis using exosomes and single-cell sequencing using droplet microfluidics, which are attracting attention as new technologies, have been newly added. Readers will be convinced that microfluidic devices have great potential for medical and biological applications.