Skin is not only the largest organ in the human body but also I believe one of the most important. It is the outermost layer of the human body and has a complex structure that is critical to fulfilling its diverse functions. It protects the body from physical and environmental assaults; provides sensation, heat regulation, water resistance, and vitamin D synthesis, and plus is the first line of defense against pathogens. In certain circumstances, skin abnormalities and damage put patient's life at risk.

The health and condition of human skin can be evaluated with a variety of imaging techniques, including magnetic resonance imaging, optical methods, and ultrasound imaging. Very recently, scientists succeeded in developing in vivo imaging technology that can simultaneously generate dual‐wavelength photoacoustic images and ultrasound images. These advances not only allow us to understand the biology behind diseases but also provide tools for early diagnosis. The amount of data collected by innovative imaging modalities nowadays is unprecedented and growing. Adding to this is the emergence of mobile phone technologies that are empowering patients with unprecedented access to high‐resolution imaging and the world's largest database, the World Wide Web. This is a formidable advance, placing the promise of improved healthcare into the hands of every individual.

One key role of skin is to form a barrier preventing the entry of external organisms and chemicals. Thus, to deliver drugs and therapies, for example, pharmaceuticals, vaccines, and moisturizers, novel strategies and techniques are needed to deliver such reagents into the skin and subsequently into the circulation. Considerable investment in research activity is driving continuous growth in the field of transdermal drug delivery, with an impressive array of active and passive‐based technologies that promise to change dermatology and skin health into the future. Many of these technologies represent a paradigm shift in dermatology.

With the emergence of new and innovative technologies, this book is very timely. It first outlines the structural characteristics of skin and skin appendages, which is followed by discussions of the key pathways involved in skin growth and development. Clinical presentations, pathophysiological mechanisms, and current clinical practices used to treat diseases affecting the skin are then introduced, including abnormal wound healing, autoimmune skin disorders, autoimmune blistering diseases, and skin cancers. Further, common preclinical models used for studying the mechanisms of diverse skin diseases, validation of novel therapeutic targets, and screening of new drugs to treat these diseases are covered. The latest imaging technologies that allow us to examine and understand changes in the skin in vivo are also introduced and covered in detail. Technologies including high‐resolution ultrasound imaging, quantitative magnetic resonance imaging, high‐resolution optical coherence tomography, and emerging hybrid imaging modalities such as photoacoustic imaging are described. The book concludes with chapters introducing emerging drug delivery technologies and potential future innovative developments. Emerging developments that repurpose traditional chemical enhancers with modern nanoparticles are described, along with reimagined transdermal delivery technologies featuring needle‐free jet injectors, microneedles, ultrasound, and iontophoresis, helping the reader to grasp emerging developments in transdermal delivery.

A theme that pervades this book is the critical role that interdisciplinary science occupies to achieve the requisite level of understanding of skin conditions and their management that is essential to creating technologies that work. Success is most often found with the integration of concepts and techniques from cell biology, chemistry, physics, optics, material science, nanoscience, clinical sciences, and critically the patient. This book will therefore motivate and enthuse students and researchers from many disciplinary backgrounds.

Personally, I appreciate the great effort that the three editors, Chenjie Xu, Xiaomeng Wang, and Manojit Pramanik, have made to bring this excellent book to completion. I anticipate that this book will catalyze new conversations across the aisles of biology and engineering within industry, academia, and clinical settings.

Zee Upton ^1,2

^1. Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore

^2. Skin Research Institute of Singapore (SRIS), Singapore