Biosensors and chemical sensors for healthcare applications are garnering interest due to their potential to provide continuous and real-time physiological information, chemical information, and noninvasive measurements of biochemical markers in human biofluids, such as tears, saliva, sweat, interstitial fluid, and human volatiles. Recent developments have focused on electrochemical biosensors and monitoring of metabolites, proteins, chemicals, and bacteria. The measurement of biophysical quantities of the human body has been studied in healthcare and medicine. Many flexible, wearable, and detachable sensors have been developed and commercialized to monitor relevant parameters in sports, healthcare, and medicine. Here, we introduce many challenges regarding the integration of sensors and biosensors into the monitoring of biological and chemical information for the internet of things (IoT) in healthcare. IoT sensors are set to improve quality of life (QoL) and living standards. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.