This work presents a new method for mass fabrication of a new microfluidic device with integrated graphene-based electrochemical electrodes by the screen printing technique for in-channel amperometric detection. Graphene-based working and counter electrodes were fabricated by screen printing graphene paste on a glass substrate, followed by screen printing of a silver/silver chloride (Ag/AgCl) reference electrode. The screen-printed substrate was then bonded to a prefabricated polydimethylsiloxane (PDMS) sheet containing microchannels via oxygen plasma treatment. The developed microfluidic device was then applied for glutathione analysis in pharmaceutical products. The method offers effective and fast glutathione detection with good analytical features including a wide dynamic range (10–500 μM) and a low detection limit (3 μM). In addition, the screen printed graphene electrode (SPGE) exhibits a good stability in a microfluidic flow system and good repeatability for amperometric detection. The method has numerous advantages including low fabrication cost, high sensitivity, high throughput and satisfactory reproducibility. Thus, it holds great promise for advanced analytical applications.

This study describes the development of a novel, ultrasensitive, and selective electrochemical sensor to determine imiquimod (IMQ) using a screen-printed carbon electrode (SPCE) modified with MXene (Ti₃C₂T_x), graphene nanoplatelets, and ionic liquid (Ti₃C₂T_x/GNPs/IL). This work reveals the synergistic effect of Ti₃C₂T_x, GNPs, and IL, where Ti₃C₂T_x and GNPs provide a large active electrode area and excellent electron transport, and IL exhibits remarkable electrocatalytic behavior. Benefiting from the excellent electrochemical properties of the composite, the developed sensing platform enabled superior electrochemical performance for IMQ in the broad linear range of 0.071–92.0 μM (R² = 0.999) with a limit of detection (LOD) of 0.487 nM and a detection sensitivity of 7.558 μA μM⁻¹ cm⁻². Meanwhile, the sensor has shown good repeatability, reproducibility, stability, and anti-interference ability and has been subsequently used to detect IMQ in cream formulations with satisfactory recoveries (98.33%–99.34%) and lower relative standard deviations (<3%). The findings indicate that the newly developed sensor can contribute to the development of a portable, robust, and high-performance sensing strategy for multidisciplinary targets.

Electrode fouling has been a major problem in the analysis of phenolic compounds. This work synthesized carbon nanofiber (CNF) by electrospinning and demonstrated the anti-fouling properties of the material. The synthesized CNF was characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, infrared spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. Three electrode preparation methods were then tested including as-spun sheet, screen printing and dropcasting. The electrochemical behaviors of CNF towards a wide range of systems were demonstrated, including reversible redox processes [e.g. K₄Fe(CN)₆ and catechol], the deposition and stripping of metal ions [e.g. Ag(I) and Cu(II)], and irreversible redox processes [e.g. resorcinol and bisphenol-A]. To highlight the advantages of the anti-fouling properties of CNF, we then used resorcinol which is an environmental contaminant as a model system and explored the analytical performances of CNF electrodes. The linear range of resorcinol detection was 10–250 μM. The sensitivity and limit of detection (3s_B m⁻¹) were determined to be 0.021 μA μM⁻¹ and 7.27 μM, respectively.