Ultraflexible Multimodal Sensors with Stable Physical Sensing and Disposable Electrochemical Calibration for...

Wearable electrochemical biosensors offer direct biochemical readouts but often suffer from enzyme deactivation, biofluid fluctuation, fouling, and calibration drift during prolonged on-body use. Here, we report an ultrathin (∼1.3 μm thick) multimodal sensing system that decouples whole-day physical monitoring from short-term disposable electrochemical calibration. The system integrates stable physical sensors for electrocardiogram, pulse, and temperature acquisition with a detachable electrochemical glucose module that provides personalized calibration labels during initial use. At the material level, the pulse sensor combines an embedded Ag nanowire network with a cracked Cr/MoO3/Cr/Au layer in an ultrathin polyimide matrix, enabling both strain sensitivity and cyclic stability. The resulting strain sensor shows a gauge factor of 5.49 in the 0-4% strain range, a response time of 55 ms, and durability over 15,000 stretching cycles. The detachable glucose sensor employs a co-crosslinked porous enzymatic matrix to delay active-site saturation, achieving a broad linear range of 0-20 mM. After three days of personalized calibration, a random-forest model using 60 s recordings of electrocardiogram, pulse, and temperature signals yields an overall tolerance-based accuracy of 81.36% and a mean absolute relative difference (MARD) of 9.12%. Furthermore, in individual on-body tracking over one day and 15 days, the glucose predictions achieved an accuracy of at least 80%. This stable-physical-sensing/disposable-electrochemical-calibration architecture provides a practical strategy for personalized glucose prediction while mitigating the long-term instability of wearable electrochemical biosensors.