Effects of laminar flow within a versatile microfluidic chip for in-situ electrode characterization and fuel cells

We demonstrated a versatile fully on-chip microfluidic electrochemical chip for in-situ electrode characterization and fuel cells application. The microdevices integrate facing working electrode (WE) - counter electrode (CE) pairs onto a microfluidic chip, solely relying on laminar flow to eliminate the chemical coupling of closed-spaced WE-CE pairs. The Pt microelectrodes are used due to the long-term sustainability and excellent biocompatibility such that the corresponding CO poisoning of HCOOH oxidation is mitigated via oxygen bleeding in the presence of dissolved oxygen. Using the Pt pseudo on-chip integrated reference electrode, the HCOOH oxidation within the microfluidic channel under laminar flow is in-situ characterized using cyclic voltammetry. The HCOOH oxidation is found to be enhanced on the dependence of flow rates, resulting from less CO poisoning due to enhanced CO consumption (associated with the oxygen bleeding) and less CO generation via convective mass transport under laminar flow. Such that the power output of HCOOH microfluidic fuel cells increases with flow rates as well. Despite the hydrodynamic resistance induced power loss increases more rapidly, the net power output is delivered at the slow flow regime.status: publishe