Electrochemical paper-based analytical device for flow injection analysis based on locally enhanced evaporation

We described a new paper-based device for performing flow injection analysis (FIA) in this article. A homemade three-electrode system, an origami paper strip, and a ceramic microheater were attached to a modular plastic supporting structure. Continuous flow in the origami paper strip was generated by the combination of capillary and the evaporation enhanced by a microheater. The proposed device was optimized and characterized by using K4Fe(CN)6/K3Fe(CN)6 as a probe of chronoamperometry. Under optimal conditions, the device can perform a single analysis within 1 min and enable over 200 injections in one sequential test. To demonstrate its applicability, the device was utilized to detect uric acid in human serum and urine samples. The limit of detection was 1.1 μM and the linear range was from 0.01 mM to 1 mM. Moreover, the testing results of the real samples agreed with the reference values. The proposed method exhibits great promise for developing a convenient and high-performance FIA system on paper substrates.