Sustainable Microelectrode Fabrication for Electrochemical Impedance-Based In Situ Monitoring In Vitro Models

The development of sustainable microelectronic fabrication strategies is increasingly important due to the environmental and economic limitations of conventional photolithography and vacuum-based metal deposition processes. These approaches typically require hazardous chemicals and high energy consumption. In this work, we address these challenges by introducing an environmental friendly fabrication route for patterning gold microelectrodes, based on inkjet-printed dextran sacrificial masks and spray-coated gold nanoparticles (AuNPs) synthesized via pulsed laser ablation. Inkjet printing enables maskless and material-efficient patterning, while spray coating provides a low-temperature and scalable route for the deposition of conductive nanoparticle networks. The resulting microelectrodes exhibit excellent electrical conductivity (sheet resistance of 37.01 ± 12.09 Ω/square and conductivity of 0.0037 ± 0.0008 MS/cm) and well-defined interdigitated geometries suitable for bioelectronic applications. To evaluate their performance, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are cultured directly on the electrodes. Electrochemical impedance spectroscopy (EIS) is employed as a label-free and real-time technique to monitor cell-electrode interactions and temporal variations in cell coverage and viability. EIS measurements, supported by equivalent circuit modeling, reveal distinct phases corresponding to initial cell adhesion, progressive remodeling of the cellular layer, and long-term reduction in viability, further validated by optical measurements. Overall, this work demonstrates a sustainable and cost-effective fabrication strategy for gold microelectrodes, enabling quantitative, noninvasive monitoring of cellular dynamics through impedance-derived parameters and image-based validation of cell coverage evolution.