Can Sweat Sensors Detect Common Diseases? A Simple Sweat Patch May Soon Achieve It.

Abstract

Diseases, infections, and hazardous chemicals alter the physiology of the human body and result in changes in the composition of extracellular and intracellular fluids. Given the difficulty in collecting extracellular and intracellular fluids, blood is typically analyzed to diagnose pathological conditions. Blood supplies oxygen and nutrients to every cell of the body and also carries away waste products; therefore, the assumption that blood composition depicts the cellular environment as closely as possible is reasonable. Blood collection, however, requires invasive procedures (such as phlebotomy or a fingerprick) and is not pleasant for the majority of the population, in some cases deterring individuals from seeking medical assistance and having blood tests. If the composition of another biofluid that could be easily tested using a noninvasive sampling technology and portable detectors would be proven to accurately depict the cellular environment, then new disease diagnostic tests could be developed, and health-testing procedures would become easier, cheaper, and appealing to almost everybody. Sweat is a biofluid that can be collected noninvasively, and some research studies suggest that sweat composition might reveal pathological conditions, chemical and biochemical exposures, and psychological stress. There are also articles in popular media that have gone even further and claimed that “sweat is the new blood” and sweat analyses will soon substitute traditional blood tests. The fact is that sweat is analyzed in medical practice in only a few specific cases (e.g., diagnosis of cystic fibrosis, hyperhidrosis, and hematohidrosis, and to optimize fluid and electrolyte intake strategies in athletes), and normal and pathological concentrations of biomarkers in sweat have not been established yet (1). It is also true that the wealth of chemical information present in the sweat has been undervalued for decades and that sweat has not been thoroughly studied for clinical diagnostic purposes. Sweat collection and analysis using conventional …