Streaming Current Based Microtubular Enzymatic Sensor for Self-Powered Detection of Urea

The emergence of microfluidic techniques coupled with flow-induced electrification has advanced the development of innovative self-powered sensors. However, selective detection of target substances using these sensors is extremely challenging, owing to the lack of recognition elements in the flow pathway. To overcome this, catalytic enzymes are immobilized on the microfluidic channel and the concentration of targets is measured via monitoring the streaming current. As an example, a urease equipped self-powered microtubular sensor is developed to selectively detect urea, a physiologically and industrially important molecule. The urease catalyzes the hydrolysis of urea into ions, increasing the pH of the fluid, which serves as the basis of the sensing mechanism. Remarkably, high sensitivity, wide detection range, short response time, and superior selectivity are reported for urinary urea detection. The accuracy and reliability of sensing in artificial urine are validated with the standard spectrophotometric method. The microtubular sensor features facile fabrication and operation and circumvents the need for sophisticated peripherals, highlighting its enormous potential in chemical and biomedical applications, such as pollutant detection, food quality assessment, disease diagnosis, and point-of-care testing.