Electrolytes such as sodium play an important role in maintaining homeostasis within the body. Sweat is the visible manifestation of a body’s attempt to correct electrolytic imbalances due to changes in hydration state. However, the appearance of dampness on clothing is insufficient to assess homeostasis because electrolyte concentration in sweat varies highly across individuals and may be perturbed by medical conditions such as diabetes and cystic fibrosis. Researchers at Drexel University have created sodium-specific colorimetric sensors that can be readily manufactured and woven into chitosan fibrous nanomats. When woven into wearable textiles, these sensors provide a more specific and sensitive measure of sodium excretion from the body, which can be used to tailor electrolyte replenishment regimens to an individual’s needs.