Thermal ablation of PMMA for water release using a microheater

Abstract

A new approach was developed in this work to ablate a micropore through a polymethylmethacrylate (PMMA) layer using a microheater for the on-demand release of water stored in a microreservoir. The size of the ablated micropore in the PMMA capping layer is mainly governed by the heater temperature profile and ablation time. Furthermore, the molten PMMA resulting from the heating energy tends to retract away from the micropore location, taking away the gold heater lines from the pore area. This prevents the possibility of any gold traces blocking the flow of water released from within the microreservoir. Simulation was conducted to find temperature profiles on the surface of the microheater, and the results were used to interpret the phenomena observed in the ablation process. Simulation was also conducted for the case when the microreservoir was filled with water. In addition, two alternative ablation materials, unexposed SU-8 and polydimethylsiloxane (PDMS), were examined as possible microreservoir capping layers. The approach developed has potential applications in microfluidic systems to release encapsulated fluids in a controllable manner.