Personalized stress monitoring: a smartphone-enabled system for quantification of salivary cortisol

Collection of salivary cortisol has been widely used as a method of investigating an array of health parameters. Monitoring of cortisol levels can help us to understand stress levels and the body's response to stressors. Traditional methods of measuring cortisol in saliva, however, require costly equipment, trained personnel, and transportation of samples to a centralized laboratory. This creates a barrier to personal monitoring of cortisol. It also adds a level of cost and difficulty to large-scale studies which require participants to store and ship their saliva samples. Here, we present a novel system in which an individual with minimal training may collect their own saliva sample and measure it at home. Our system utilizes a lateral flow assay, a portable imaging device, and a smartphone to give salivary cortisol results in less than 15 min. We also demonstrate the use of our system on samples from a human study and give results from that study, which analyzes the relationship between cortisol levels and alertness across multiple days.