Easily detachable glass bonding in microfluidic device based on hydrophilic interactions

Abstract Microfluidic devices for chemical and biological processes are commonly constructed of glass. However, glass substrates bonded together by conventional thermal fusion or anodic processes are difficult to detach and reuse. Also, repeated bonding and separation after low-temperature processing has not been sufficiently investigated, and cracks are sometimes observed following substrate separation. This work demonstrates a simple, quick bonding method producing weakly bonded, detachable substrates on the basis of hydrophilic interactions. Leakage tests indicated that such bonds were able to withstand pressures up to 200 kPa, which is sufficient for typical microfluidic experiments. Flow rate measurements confirmed an absence of leakage and the thin bonding layers (approximately 50 nm or less) were found not to affect the channel depth or flow rate in microfluidic channels. The water-based bonding used in this study is applicable to microfluidic devices using organic solvents and could lead to the fabrication of reusable microfluidic devices allowing repeated bonding and detachment.