Fast packaging by a partially-crosslinked SU-8 adhesive tape for microfluidic sensors and actuators

Abstract This paper proposes a novel SU-8 adhesive tape by using the dose-controlled UV exposure method, which enables the fast packaging with fluidic interconnections for microfluidic sensors and actuators. The conventional packaging for microfluidic devices demands two complicated steps: (1) to drill the fluidic connections on the glass cover in the first process, which may make the glass cover broken due to poor machinability of glass; and then (2) to spread a thin adhesive on the cover in the second process, which may induce the clogging of the fluidic connections. To realize a fast and simple packaging for microfluidic devices, we propose a versatile method that employs a partially-crosslinked SU-8 adhesive tape composed of an adhesive layer (uncrosslinked SU-8) onto the backing material (crosslinked SU-8) with fluid connections, which can be fabricated in one simple step. We choose a suitable substrate from which we can release the SU-8 adhesive tape and build the mathematic model of the dose-controlled UV exposure method which can estimate the thickness of the crosslinked SU-8. Then, we investigate the influence of developing time on the formation of the SU-8 adhesive tape. We also examine the bonding quality by using the visual inspection method and measuring the bonding strength based on the pull-test experiments. Moreover, its applications to a T-junction droplet generator and a shallow channelprove the feasibility to be widely applied to microfluidic sensors and actuators.