Battery-free and wireless tag for in situ sensing of urinary albumin/creatinine ratio (ACR) for the assessment of albuminuria

Random urine albumin-to-creatinine ratio (ACR) is highly correlated with 24-hour urine albumin, which is of great significance for the diagnosis of nephropathy, diabetes, hyperglycemia, and hypertension. In this study, we developed a battery-free, wireless, and flexible electrochemical tag for in situ quantification of urinary ACR. A flexible circuit electrochemical board is integrated with chronoamperometry (CA) and differential pulse voltammetry (DPV) for the detection of creatinine and albumin, respectively. Near field communication (NFC) module is applied for wireless power obtaining and data transmission. A disposable screen-printed flexible electrode array connected with the circuit board, including a non-enzymatic sensor for creatinine detection and an electrochemical immunosensor was applied for albumin detection. Within the effective working distance (1 ~ 2 cm), ACR sensing platform could be powered wirelessly by the NFC-enabled smartphone via electromagnetic coupling , performing real-time urine ACR detection and data transmission. The tag showed high consistency with clinical laboratory methods to several synthetic urine samples. This platform provides a rapid and convenient method for the detection of urinary biochemical substance, such as ACR, which has a broad prospect in mobile health and point-of-care testing (POCT).