Skin-applied sensors for measuring vital signs including body temperature, heart rate, respiration rate, pulse oximetry, and movement; devices for analyzing sensor-measured skin temperature to core body temperature; skin applied devices and systems to measure vital signs for fever detection, heart rate detection; skin applied devices and systems to detect concussion, heat exhaustion, software applications for use in conjunction with skin applied devices, smartphone software applications for use in conjunction with skin applied devices for receiving, processing, and displaying temperature, heart rate, respiration rate, pulse oximetry, and movement data from skin-applied sensors; algorithms for translating sensor-measured skin temperature to core body temperature, software used to detect concussion and heat exhaustion for athletes, software as a service (SaaS) used in connection with skin applied devices, featuring cloud-based electronic medical records systems for storing, managing, and accessing patient medical data, including temperature, heart rate, respiration rate, pulse oximetry, and movement data; computer software development and maintenance services for healthcare applications used in connection with skin applied devices, including algorithms for translating sensor-measured skin temperature to core body temperature, SaaS designed to be used to detect concussion and heat exhaustion for athletes, design and development of software to be used in connection with skin applied devices for healthcare data analysis and visualization; providing an online platform featuring a clinician dashboard display to be used in connection with a system comprising skin applied devices for monitoring and analyzing temperature, heart rate, respiration rate, pulse oximetry, and movement data collected from skin-applied sensors