Graphene microelectrodes for real-time impedance spectroscopy of neural cells in organ-on-a-chip

This study presents the development and characterization of a graphene-based sensor integrated into a microfluidic chip for real-time monitoring of cell growth and viability in an organ-on-a-chip platform. The sensor fabrication involved the metabolization of graphene from graphite using a simple and cost-effective method. The sensor design, created using SolidWorks, featured electrodes capable of detecting environmental changes through impedance sensing. A mold was created using a cutter plotter to overcome challenges in achieving the desired sensor shape, and the graphene electrodes were then printed on a polyester (PETE) membrane. The conductivity of the electrodes was optimized through annealing, by considering the temperature limits of the membrane. Annealing at 150 °C for 40 min yielded electrodes with the desired conductivity while maintaining membrane integrity. The annealing parameters were confirmed through cell culture experiments for compatibility with cellular growth. The scaled electrodes were integrated into a microfluidic chip, and their performance was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The results demonstrated the successful functioning of the electrodes within the chip. The developed graphene-based sensor offers promising applications in other organ-on-a-chip studies, as well as in cellular studies and biosensing, through real-time monitoring of cell growth and viability that was achieved by measuring impedance changes resulting from cell attachment.