dc.description.abstract | In this study, the microchannel sealed with double-sided adhesive tape to achieve high bonding strength and high-quality microfluidic system. Bonding process was related to the microchannel integrity in the microfluidic system. Besides the dry adhesive tape bonding, it must be fabricated with the high temperature and pressure or via solvent conditions, which lead to low yield and high cost. The tape bonding is simple to operate, and the material is easily obtainable. Moreover, an effective bonding can be achieved at room temperature, low pressure and short bonding time. However, selecting suitable tapes and optimized bonding parameters in the simple manufacturing process can effectively improve the quality of the microfluidic chip. Due to the viscoelasticity of adhesive tape and substrate properties to produce the bubble phenomenon, the bonding strength will be affected. The bonding strength is influenced by two factors: the bubble and thickness of the tape. Few scholars discuss in detail the bonding strength factors with the tape bonding method. Therefore, we focus on investigating dry-adhesive bonding in this thesis.
In order to fabricate high bonding strength and high-quality microfluidic chips, this study discusses three parameters that affect the performance: tape thickness, bonding time, and properties of cover layer. This is achieved using 30μm, 50μm, 60μm, and 80μm thick double-sided tape and 0sec (hand press), 5sec, and 15sec bonding time, and bonding with inflexible cover layer and flexible cover layer respectively. The bubble ratio was analyzed by microscopic image, the bonding strength was measured, and the cross-section morphology of the channel was observed. The results were obtained by bonding with 60μm double-sided tape with 15sec bonding time of high bonding strength and competent interface morphology. The average bubble ratio of the inflexible cover layer is 0.47±0.18%, which is 7.97% lower than 0sec bonding time, and the bonding strength is increased by 2.07 bar to 11.26±1.49 bar; the average bubble ratio of the flexible cover layer is 0.25±0.06%, decreased about 2.11% compared to 0sec, and increases the bonding strength of about 0.97 bar to 3.93±0.36 bar. The inflexible cover layer is stronger than the flexible cover layer since the bonding strength increased 7.3 bar due to its better rigidity. Though the flexible cover layer also has enough bonding strength for the microfluidic chip.
The cross-section of the channel can verify the interface adhesive is not squeezed into the channel, and the shape of the channel remains constant without deformation or clogging. In addition, the devices were stored in the atmosphere for 30 and 60 days to observe the bonding-quality stability. The results show that the storage time does not significantly effect high-strength devices. It can be a reference for the preparation of microfluidic system by tape bonding process and the selection of tapes, which can improve the process yield and apply to mass production requirements in the future. | en_US |