Single-Fiber Hair Holder: a hair fiber mounting tool for advanced cuticle surface analysis.

Single fiber studies are essential to the development, testing and evaluation of new actives, formulations, and technologies in hair care. However, these studies have been constrained by the highly variable nature of hair fibers, as well as difficulties in their handling, making single fiber research expensive, time-consuming, low-throughput, and difficult to replicate. In response to this unmet need, a new tool, the Single-Fiber Hair Holder (SFHH), has been designed and developed to expedite and broaden accessibility of single fiber imaging and analysis studies; the current report outlines the design features of the tool and proof-of-concept testing. This easy-to-use hair mounting system, by stabilizing and gently straightening single hair fibers, facilitates relocation of the same surface region of hair cuticle at the micrometer scale before and after application of treatments, across a diverse range of hair types. Use of the SFHH reduces sample preparation time to approximately 1 min, reduces laboratory consumables as it is a re-useable 3D printed mount, and optimizes study design by allowing relocation of up to three regions along a fiber. The SFHH represents a new frontier in methodology for single fiber studies as it provides a new, standardized tool that supports top-quality single fiber analysis within the cosmetic industry.