Summary of oral wearable monitoring devices. (a) Mouthguard glucose sensor and its reaction with the open-loop injection system and phantom jaw. Reproduced with permission 173. Copyright 2016, ELSEVIER. (b) Pacifier Biosensor and schematic amperometry response of glucose monitoring. Reproduced with permission 174. Copyright 2019, American Chemical Society. (c) The intraoral sodium intake sensor enables real-time responses to various diets in vivo by a human subject. Reproduced with permission 175. Copyright 2018, PNAS. (d) Monitoring fluctuations in the local oral microenvironment pH using wearable devices to detect caries lesions Reproduced with permission176. Copyright 2022, Nature. (e) A wearable cellulose acetate-coated mouthguard biosensor for in vivo salivary glucose measurement. Reproduced with permission 177. Copyright 2020, American Chemical Society. (f) A mouthguard biosensor for uric acid that has built-in wireless electronics. Reproduced with permission 178. Copyright 2015, ELSEVIER.