A powerless, gas-permeable, flexible and transparent carbon micromesh electrode for simultaneous ascorbic acid detection and pH monitoring

Ascorbic acid (AA) is a critical nutrition and chemical for humans, due to its crucial role in metabolic processes and medical treatments. It is necessary to develop a simple and rapid method for real-time tracking AA level in the body. In this work, we fabricated a powerless, gas-permeable, flexible and transparent AA biosensor based on carbon micromesh electrode (CME). The AA biosensor worked without an external power supply and exhibited excellent performances, including high transmittance (>95%), wide detection range (1 μM–1 mM), low limit of detection (10 nM), good selectivity and long-term storage stability (30 days). In addition, we integrated a pH-sensing electrode to correct the AA analysis. A layer of polyaniline (PANI) film was electrodeposited on the carbon micromesh as pH-sensing electrode that had an average sensitivity of 58.1 mV/pH with a high correlation coefficient ( R 2  = 0.997) within the physiological range of human body fluids (pH 4.0–8.7). To verify the availability of the CME in practical application, the Ag/C electrode was used as reference electrode to fabricate the integrated dual-functional biosensors for artificial tears detection. The CME-based biosensors showed good sensitivity, selectivity and correlation coefficient, indicating its excellent practicability towards wearable electronics.