Advances and applications of wearable electrochemical sensors in personalised medicine and precision agriculture: a systematic review

Wearable electrochemical sensors have advanced in two application domains seldom examined together: personalised medicine, where on-body and microneedle devices interrogate sweat, interstitial fluid, saliva and tears, and precision agriculture, where leaf patches, in-planta microneedles and soil electrodes track phytohormones, agrochemicals and nutrients. Following PRISMA 2020, we screened 1,687 Scopus records using a single pre-specified search string, reproduced in full in the Supplementary Information, and analysed 201 primary studies. Both literature rest on an almost identical technology stack flexible substrates, nanostructured electrodes, enzymatic, affinity, imprinted and ionophore-based recognition, and wireless readout yet only fourteen eligible studies span both fields. Applying a five-level validation taxonomy derived from technology-readiness and analytical method-validation practice, we find analytical performance excellent but deployment evidence scarce: 4.0% demonstrated field or free-living operation, 53% stopped at on-body or on-plant testing, and drift, biofouling and reference-method benchmarking were reported in 24%, 27% and 32% respectively. These three figures are reporting rates rather than measures of adequacy: they record whether an issue was addressed at all, not whether it was validated over the period for which the device is claimed to work. The bottleneck is no longer sensitivity but sustained, reference-anchored operation; we propose a five-item validation-reporting framework, which adds the duration of continuous operation to validation tier, drift, biofouling and reference-method benchmarking, to make deployment readiness comparable across domains.