LAUSR

Interstitial fluid (ISF), as an emerging source of biomarkers, is unmistakably significant for disease diagnosis. Microneedles (MNs) provide a minimally invasive approach for extracting the desired molecules from ISF. However, existing MNs are limited by their capture efficiency and sensitivity, which impedes early disease diagnosis. Herein, an engineered wearable epidermal system is presented with a combination of reverse iontophoresis and MNs for rapid capture and sensing of Epstein‐Barr virus cell‐free DNA (an important biomarker of nasopharyngeal carcinoma). Owing to a dual‐extraction effect demonstrated by reverse iontophoresis and MNs, the engineered wearable platform successfully isolates the cell‐free DNA target from ISF within 10 min, with a threshold of 5 copies per µL and a maximum capture efficiency of 95.4%. The captured cell‐free DNA is also directly used in a recombinase polymerase amplification electrochemical microfluidic biosensor with a detection limit of 1.1 copies per µL (or a single copy). The experimental data from immunodeficient mouse models rationalizes the feasibility and practicality of the wearable system. Collectively, the developed method opens an innovative route for minimally invasive sampling of ISF for cell‐free DNA‐related cancer screening and prognosis.