Black phosphorus (BP), also known as phosphorene, has attracted recent scientific attention since its first successful exfoliation in 2014 owing to its unique structure and properties. In particular, its exceptional attributes, such as the excellent optical and mechanical properties, electrical conductivity and electron-transfer capacity, contribute to its increasing demand as an alternative to graphene-based materials in biomedical applications. Although the outlook of this material seems promising, its practical applications are still highly challenging. In this review article, we discuss the unique properties of BP, which make it a potential platform for biomedical applications compared to other 2D materials, including graphene, molybdenum disulphide (MoS₂), tungsten diselenide (WSe₂) and hexagonal boron nitride (h-BN). We then introduce various synthesis methods of BP and review its latest progress in biomedical applications, such as biosensing, drug delivery, photoacoustic imaging and cancer therapies (i.e., photothermal and photodynamic therapies). Lastly, the existing challenges and future perspective of BP in biomedical applications are briefly discussed.

Microfluidic separation technology has garnered significant attention over the past decade where particles are being separated at a micro/nanoscale in a rapid, low-cost, and simple manner. Amongst a myriad of separation technologies that have emerged thus far, acoustic microfluidic separation techniques are extremely apt to applications involving biological samples attributed to various advantages, including high controllability, biocompatibility, and non-invasive, label-free features. With that being said, downsides such as low throughput and dependence on external equipment still impede successful commercialization from laboratory-based prototypes. Here, we present a comprehensive review of recent advances in acoustic microfluidic separation techniques, along with exemplary applications. Specifically, an inclusive overview of fundamental theory and background is presented, then two sets of mechanisms underlying acoustic separation, bulk acoustic wave and surface acoustic wave, are introduced and discussed. Upon these summaries, we present a variety of applications based on acoustic separation. The primary focus is given to those associated with biological samples such as blood cells, cancer cells, proteins, bacteria, viruses, and DNA/RNA. Finally, we highlight the benefits and challenges behind burgeoning developments in the field and discuss the future perspectives and an outlook towards robust, integrated, and commercialized devices based on acoustic microfluidic separation.

Active and passive techniques for bubble trapping and control in various microfluidic applications.