Demonstration of a Transparent and Adhesive Sealing Top for Microfluidic Lab-Chip Applications.

A transparent and adhesive film-based enclosing and sealing method is here presented for out-of-cleanroom-based open-form microfluidic devices. The commercially available polyester flexible film known as Microseal 'B' is presented in this paper as a cover seal for open-form microfluidic devices. This film is adaptable to high working temperatures and is biocompatible. The quality of the sealing film was investigated by leak tests, fluorescence tests, and contact angle measurements. The investigations revealed its sealing strength, fluorescence detection compatibility, and surface wettability. It was found that the proposed sealing polyester film on the 3D-printed device could sustain a gauge pressure of 2.7 atm at a flow rate of 4 mL/min without any leaks. It also provided fluorescence detection compatibility and an intensity-to-background ratio in the range of 2.3 to 4.5 for particle sizes of 5 μm and 15 μm, respectively, which is comparable with the performances of other sealing materials. The film's hydrophobicity is comparable to other polymers used in microfluidics. This paper concludes by showcasing some applications of such transparent tops in classical microfluidic devices used for droplet generation and fluid mixing, in order to demonstrate the prospects of this fabrication technique in lab-on-a-chip devices.