Multi-amino acid quantification device using amino acid-binding enzymes and color-forming reagents

This study reports the development of a compact tabletop onsite device designed to facilitate non-invasive, rapid, low-cost, and user-friendly health evaluation by quantifying amino acids in sweat through enzymatic reactions. The system employs freeze-dried reagents coated onto a multilayer PET film-based microfluidic channel. As sweat extract flows through the channel, each target amino acid reacts selectively with its corresponding enzyme, and the resulting color change is quantified within a short onsite analysis time. Sweat was collected using a pre-wetted non-woven patch, automatically extracted into liquid form with a dedicated cassette, and applied to the analytical film device. The extract contained multiple amino acids, including glycine, aspartic acid, leucine, histidine, and serine, which were detected by their respective enzymes. Although further optimization of the enzymatic reaction conditions is required to reduce variability among amino acids, the present device demonstrates a practical platform for convenient onsite multi-amino acid analysis in sweat, with potential applications in beauty, sports, health screening, agriculture, environmental monitoring, and space exploration.