Reverse iontophoresis sensing electrode for joint detection of pH, NH4+, and lactic acid

With the rapid development of integrated electronic circuit technology, biological fluid-electricity integrated detection systems have gradually become a research hotspot. Researchers have integrated biological fluid electrical detection methods into circuits and developed small, low-power, portable detection devices equipped with sensing electrodes, which can achieve continuous monitoring of human health parameters. In recent years, the integration of reverse iontophoresis technology that can be used to extract body fluids with electrochemical sensors has opened up the possibility of flexible, portable biochemical sensing with excellent detection sensitivity. Herein, we present a method for extracting biofluids based on reverse iontophoresis technology, coupled with electrochemical sensing techniques for the simultaneous detection of various biomarkers in body fluids. The multi-channel sensing electrode was modified layer by layer using nitrogen-doped graphene (N-Gr), ion-selective membrane, or lactate oxidase for rapid and sensitive detection of pH (3–8), ammonium ion (NH₄⁺) (0.1 mM–50 mM), and lactic acid (1 mM–50 mM). Subsequently, an integrated system for electrical stimulation extraction and sensing analysis based on reverse iontophoresis was established and experimentally tested. Experimental results demonstrated that the multi-channel joint detection sensing electrode has excellent sensing linearity, specificity, repeatability, and long-term stability. Finally, a smartphone-based WeChat applet was developed, which can realize parameter setting, function selection, and result display of sensor detection. In this study, reverse iontophoresis technology was used to collect body fluids, and the important biomarkers pH, NH₄⁺, and lactic acid in the body fluids were detected. Overall, this research presents an integrated detection system and a multi-channel sensing scheme for the detection of important biochemical markers in bodily fluids, thereby providing potential value for health monitoring applications.