Liquid atomization in a microfluidic channel for electrodeposition coating process of commercial vehicle*

Liquid chemicals for cleaning or surface preparation that remain in the gap between two panels joined by spot welding have a serious impact on the quality of the electrodeposition process. To solve this problem, we present a liquid emptying technology with acoustic excitation which can atomize the remaining liquid in wide microfluidic channels with a height of tens to hundreds of micrometers. A microfluidic channel chip fabricated to mimic the vehicle panel gap and piezoelectric transducer capable of generating ultrasonic wave with various frequency were used. For understanding the unwanted filling of the liquid inside the microfluidic channel, the fabricated chip is repeatedly immersed in the liquid medium at various tilting angles, and liquid filling behavior is observed. To evaluate liquid emptying performance, we conducted an liquid atomization experiment by changing not only the electrical signal applied to the transducer but also the channel height and tilting angle. This in-channel droplet atomization technology with ultrasonic excitation is expected to be applied to a variety of industries that require the removal of liquids from precise structures.