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

• Published in: Sensors and actuators. A. Physical. 2019-04, Vol.289, p.77-86
• Main Authors: Mao, Zebing, Yoshida, Kazuhiro, Kim, Joon-wan
• Format: Article
• Language: English
• Subjects: Actuators; Adhesive bonding; Adhesives; Bonding; Bonding strength; Components; Crosslinking; Dose-Controlled UV exposure method; Fluid dynamics; Fluid mechanics; Fluidic sensors and actuators; Glass; Machinability; Mechanical properties; Microfluidic devices; Packaging; Partially photo-crosslinked SU-8; Sensors; Substrates; Ultraviolet radiation
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2019.02.020

Figure: Schematics of the fabrication process of the SU-8 adhesive tape by using a dose-controlled UV exposure method. [Display omitted] •A partially-crosslinked SU-8 adhesive tape was proposed by using the dose-controlled UV exposure, for the fast packaging of fluidic devices.•The proposed SU-8 adhesive tape consists of an adhesive layer (uncrosslinked) onto the backing material (crosslinked) with fluid connections.•The applications to a T-junction droplet generator and a shallow channel demonstrate the feasibility of our proposed method. 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.