Richena Marina, Noble Alasdair, Parker Kim, Bhogal Ranjit K, Messenger David, Clerens Stefan, Harland Duane P
AgResearch Ltd, Christchurch, New Zealand.
Unilever R&D Colworth, Colworth Science Park, Bedford, UK.
Int J Cosmet Sci. 2025 Aug;47(4):676-690. doi: 10.1111/ics.13057. Epub 2025 Mar 31.
Characterizing the fibre properties of individuals with different hair textures across several ethnicities is important for understanding how hair shape varies within and between groups, and how these may influence consumer needs. Here, we present a high-throughput scanning electron microscope (SEM) method for simultaneous measurement of cross-sectional single hair shape parameters from hundreds of hairs per sample, which has not been feasible previously. We demonstrate the power of the method through application on a population with diverse hair types.
Scalp hairs were collected from individuals located in the United States of America. Each hair sample (consisting of up to several hundred fibres) was classified using two different methods, one during clinical collection [hair texture Types 1-4] and later another blind standard laboratory method [hair curliness classification Types I-VIII]. Additional clinical data were collected on age and self-identified ethnicity. Hair shape parameters (cross-sectional area, ellipticity, shape factors) were measured using a SEM sample preparation, imaging and image analysis method. SEM data were analysed with respect to clinical texture, age and self-identified ethnicity and subsequent hair curliness classifications.
The SEM method generated sufficient data from each sample to identify trends, and we found some statistically significant differences between SEM hair shape parameters and clinical sample types, as well as with laboratory curliness classifications. In the curliness classification, there was an expected tendency between hair curliness and aspect ratio: curlier hairs were more elliptical than straight hairs. In terms of the hair grouping types, in the age group, older individuals had thinner hairs than young ones. In the texture group, individuals in Texture Type 1 had thinner hairs than Texture Types 2, 3 and 4. Texture Types 3 and 4 had hairs with a more elliptical profile than individuals in Texture Types 1 and 2.
The SEM method was reliable to quantify cross-sectional hair parameters within populations of donors with different types of hair. This approach corroborates clinically assessed hair type and curliness classification systems and provides a more thorough characterization of hair shape variation between and within individuals and ethnicities.
了解不同种族中具有不同头发质地的个体的纤维特性，对于理解头发形状在群体内部和群体之间如何变化，以及这些变化如何影响消费者需求至关重要。在此，我们提出了一种高通量扫描电子显微镜（SEM）方法，可同时测量每个样本数百根头发的横截面单根头发形状参数，这在以前是不可行的。我们通过将该方法应用于具有不同头发类型的人群来展示其强大功能。
从美国的个体收集头皮毛发。每个头发样本（最多由数百根纤维组成）使用两种不同方法进行分类，一种在临床收集时进行[头发质地类型1 - 4]，之后再采用另一种盲法标准实验室方法[头发卷曲度分类类型I - VIII]。还收集了关于年龄和自我认定种族的其他临床数据。使用SEM样本制备、成像和图像分析方法测量头发形状参数（横截面积、椭圆率、形状因子）。针对临床质地、年龄、自我认定种族以及后续的头发卷曲度分类对SEM数据进行分析。
SEM方法从每个样本中生成了足够的数据以识别趋势，并且我们发现SEM头发形状参数与临床样本类型之间以及与实验室卷曲度分类之间存在一些具有统计学意义的差异。在卷曲度分类中，头发卷曲度与纵横比之间存在预期趋势：卷曲头发比直发更椭圆。在头发分组类型方面，在年龄组中，年长者的头发比年轻人的更细。在质地组中，质地类型1的个体头发比质地类型2、3和4的更细。质地类型3和4的头发比质地类型1和2的个体的头发轮廓更椭圆。
SEM方法对于量化不同类型头发供体群体中的横截面头发参数是可靠的。这种方法证实了临床评估的头发类型和卷曲度分类系统，并提供了对个体和种族之间以及个体内部头发形状变化更全面的表征。
