Electrochemical time of flight flow sensor

In this paper we propose a time of flight (TOF) micro flow sensor for aqueous fluids using an in situ electrochemically produced tracer. The sensor consists of two electrochemical cells integrated in the flow channel. The upstream cell functions as an oxygen producer and the downstream cell is an amperometric oxygen sensor. Oxygen is produced at the upstream cell and detected at the downstream cell. Since the geometry set-up of the flow channel is known, the flow rate is derived from the time difference between the signals. The measurement results are stable in virtue of its working mechanism. Unlike TOF flow sensors using thermal tracers, there is no need of delicate microstructures in this sensor since the diffusion of oxygen in the wall of the channel is negligible. Backward implicit finite difference simulation is used to analyze the transportation of the oxygen pulse in the channel. The measurement results in different aqueous fluids are shown.