A three-dimensional micropillar electrode array-based microfluidic sensor for sensitive and stable voltammetric detection of phosphate

In this study, a sensor based on a three-dimensional gold micropillar array of working electrodes was designed and fabricated using microfluidic chip technology and electrochemical methods. The geometrical parameters of the micropillar working electrode array were optimized through simulation analysis to enhance the efficiency of the electrochemical reaction. The main results showed that the developed sensor exhibited a high sensitivity of -0.032 μA (μmol L^-1)^-1 for phosphate with a low limit of detection (LOD) of 0.7 μmol L^-1 (S/N = 3) and a correlation coefficient of 0.99, which demonstrated a good linear relationship in the concentration range of 5-50 μmol L^-1. In the consistency and stability tests, the sensor showed a low relative standard deviation (RSD = 1.3%) and only a 7% drop in response current over 30 days, demonstrating its long-term stability. In the ion interference test, common water ions had little effect on the sensor's detection performance, demonstrating good resistance to interference. The sensor can be applied to the real-time detection of phosphate in groundwater.