Dynamic characterization of a polymer-based microfluidic device for distributed-load detection

This paper presents an experimental study of the dynamic characteristics of a polymer-based microfluidic device for distributed-load detection. The core of the device is a rectangular polymer microstructure embedded with an electrolyte-filled microchannel. Exerted by a rigid cylinder probe, distributed loads deflect the microstructure and consequently alter the geometry of electrolyte in the microchannel, yielding recordable resistance changes. Using a customized experimental setup, the sinusoidal response of the device is measured with the overall sinusoidal load as the input and the sinusoidal deflection of the device as the output. The recorded data are processed to obtain the amplitude ratio, F0/z0, of the load to the device deflection and the phase shift, ϕ, between the two signals. These two variables are then utilized to fit the dynamic stiffness and damping of the device for extracting its system-level parameters. Three devices of different designs are fabricated and tested, and best-fit values for the system-level parameters of these devices are extracted. Through comparing the measured results among these devices, non-intuitive insight is shed on how key device design parameters and the probe used affect the dynamic characteristics of the device.