Frontiers in nanotribology: Magnetic storage, bio/nanotechnology, cosmetics, and bioinspiration

The word "nanotribology" was introduced for the first time in the title of a paper and a book in 1995. This field encompasses fundamental studies of surface characterization, adhesion, friction, scratching, wear, and lubrication at the atomic scale. At most solid-solid interfaces of technological relevance, contact occurs at numerous asperities. It is of importance to investigate a single asperity contact in the fundamental tribological studies. A nanoprobe sliding on a surface in probe-based microscopies, including atomic force microscopy (AFM) at ultralow loads, simulates one such contact. AFMs and depth-sensing nanoindentation techniques are also used for nanomechanical characterization. The field is referred to as nanomechanics. AFMs can also be used for nanoelectrical characterization which includes electrical resistance, surface potential, and capacitance mapping. Research in the field of nanotribology and nanomechanics was initiated by or for the magnetic storage industry in the late 1980s. Later in the mid-1990s, nanotribology and nanomechanics research became important in bio/nanotechnology devices which involve relative motion, as well as ultrathin films. Adhesion, friction and wear issues in bio/nanotechnology devices led to the development of the field of bio/nanotribology. Research in ultrathin films used in the cosmetic industry, including hair, hair conditioner, skin, and skin cream, led to development of the field of nanotribology in cosmetics. Biologically inspired design, adaptation, or derivation from nature, referred to as biomimetics or bioinspiration, can guide us to initiate and produce nanomaterials, nanodevices, and processes in a sustainable and environmentally friendly manner. So called, green nanotribology research is important in this field. This perspective article presents an overview of fundamental understanding of nanotribology and nanomechanics and their applications in various fields ranging from magnetic storage, bio/nanotechnology, hair and hair conditioner, skin and skin cream, and bioinspiration (green nanotribology).