(Invited) Triboelectric Identification of Amino Acids

Triboelectrification necessitates a frictional interaction between two dissimilar materials, and their contact electrification is characteristically based on the polarity variance in the triboelectric series. Utilizing this fundamental advantage of the triboelectric phenomenon, different materials can be identified according to their contact electrification capability. Herein, we perform an in-depth analysis of the amino acids present in the stratum corneum of human skin, and we quantify them regarding triboelectric polarization. The principal focus of this study lies in analyzing and identifying the amino acids present in copious amounts in the stratum corneum to explain their positive behavior during the contact electrification process. Thus, we present an augmented triboelectric series of amino acids with quantified triboelectric charging polarity by scrutinizing the transfer charge, work function, and atomic percentage. Furthermore, we detect the chirality of aspartic acid as it is most susceptible to racemization with clear consequences on the human skin. We expect this study to accelerate research exploiting triboelectrification and provide valuable information on the surface properties and biological activities of these important biomolecules.