Reversible bonding of thermoplastic-based microfluidics with freeze-release adhesive

Bonding is the critical step in the fabrication of thermoplastic-based microfluidic devices to enclose the microchannel. Conventional bonding method for thermoplastic is usually irreversible with thermal fusion or chemical treatment approaches. The reversible bonding for microfluidic applications is sometimes desirable to retrieve the samples inside the microstructures. In this study, a low cost, rapid, and low-residue reversible bonding method was proposed with the freeze-release adhesive. The poly(butyl methacrylate)-based freeze-release adhesive can achieve a relatively high bonding strength between the thermoplastic plates after applying a gentle compression force with/without thermal treatment. The detachment of the thermoplastics plates can be achieved by either storing the bonded chip in the refrigerator for several minutes or using freeze spray (immediate detachment). With the help of freeze-release adhesive, bonding between PMMA plates and hybrid bonding between PMMA and PS/PC was achieved. Bonding strengths were studied in detail with various temperature settings in the bonding process. The detachment process was also studied with different low-temperature treatment durations. The biocompatibility of the freeze-release adhesive was also discussed in this study. Compared to the previous reversible bonding methods, the proposed reversible bonding approach is simple to handle, rapid on bonding/debonding, low residue, and harmless to biological samples inside the microfluidic chip.

Automated summary

A low-cost, rapid, and low-residue reversible bonding method using freeze-release adhesive was proposed in this study. The poly(butyl methacrylate)-based adhesive achieved high bonding strength between thermoplastic plates with gentle compression force and/or thermal treatment. The plates could be detached by storing the bonded chip in the refrigerator or using freeze spray. The proposed method is simple, rapid, low residue, and harmless to biological samples inside the microfluidic chip.