Nanowire Sensor Calibration and Performance Evaluation in Microfluidic Flow Velocity Monitoring

A microfluidic chip, integrated with a contact flow velocity sensor, was fabricated. A single gold nanowire prepared by nanoskiving was positioned across the bottom of a microfluidic channel. Real-time monitoring of the microfluidic flow velocity is achieved by leveraging the principle of forced heat exchange between the fluid and the solid nanowire. To harmonize theoretical calculations and experiments, leading to the derivation of a conversion formula between the flow equivalence factor and the flow velocity. Analysis of experimental data, specifically curves of resistance versus time, yields two characteristic parameters for the nanowire sensor: the step size of the flow equivalence factor and the resistivity variation. The performance of nanowire sensor was further analyzed by examining the patterns exhibited in the relationship between characteristic parameters (resolution and response characteristics) and both voltage and inlet flow rate. This work has potential applications in biomedical sensing, microfluidic mixing, and other areas where flow velocity control is required.