Ontwerp van een adsorptie gebaseerde elektrochemische sensor

The development of reliable, low-cost electrochemical sensors depends critically on the properties of the electrode materials used. This thesis explores how the interplay between surface area, adsorption behavior, and conductivity in carbon and zeolite-based materials affects electrochemical performance—particularly for applications in small-molecule sensing. Special emphasis was placed on understanding how hybrid coatings, consisting of conductive carbon black (Vulcan XC-72R) combined with microporous zeolites (all-silica zeolite β and ZSM-5), influence the electrochemically active surface area (EC-ASA) and analyte interaction. By employing both capacitive and redox-probe-based methods, the work demonstrates that these hybrid materials enhance surface accessibility and sensitivity, despite the zeolites being non-conductive themselves. This highlights the need for context-dependent surface area characterization when designing sensor interfaces. A central theme in the thesis is the role of adsorption in shaping electrochemical signals. It is shown that strongly adsorbing analytes can significantly distort EC-ASA measurements, depending on the probe used. This behavior is especially pronounced in porous materials and can lead to considerable overestimations if not properly accounted for. The combination of adsorption studies with electrochemical analysis offers a more nuanced understanding of how molecules interact with electrode surfaces. Based on these insights, a disposable electrochemical sensor was designed for the detection of paracetamol (PAR). The sensor achieved a detection limit as low as 150 nM and demonstrated selective response even in the presence of interfering substances like glucose. This selectivity was directly linked to the tailored adsorption properties of the coating materials, emphasizing the practical value of surface chemistry control in real-world sensing applications. Finally, the work evaluates surface modifications intended to further improve analyte capture. While increased adsorption was achieved in some cases, this came at the cost of reduced conductivity and accessible surface area. The findings offer clear guidance for future material design, suggesting that in situ modification on already-structured electrodes or using flat model systems could overcome current limitations. Overall, this research provides a materials-based framework for improving both the sensitivity and selectivity of electrochemical sensors, with potential applications in diagnostics, environmental monitoring, and beyond.