Recent trends in non-invasive on-body chemical sensing

Recent advances in non-invasive on-body chemical sensing over the last five years (2018–2022) are summarized in this review. The review illustrates major achievements enabled by chemical sensors and biosensors based on electrochemical and optical transduction that were tested on human subjects. The review is limited to purely non-invasive analysis of body fluids and therefore sampling methods using e.g. microneedles and implantable sensors are excluded. Based on the recent literature, major research efforts are currently directed towards epidermal chemical sensors, in particular electrochemical and optical sensors and biosensors for determination of electrolytes, pH and metabolites in sweat. Other types of samples, such as tears, saliva and dermal interstitial fluid, receive less attention. However, glucose monitoring often relies on interstitial fluid as a representative sample. Recent approaches utilize innovative design of chemical sensor and biosensor platforms as well as microfluidic sampling for non-invasive on-body chemical sensing.