One-Step Fabrication of Packaged Glass Microheater Using Selective Laser Welding

The increasing demand for miniaturized and versatile microdevices has driven advancements in micropatterning technologies; however, packaging considerations are often overlooked or addressed with basic additions. This study introduces a new selective laser welding process facilitated by a silver (Ag) thin film, enabling simultaneous micropatterning and packaging in a single step. In the proposed method, the Ag thin film serves as a laser absorber in the welded area, where it transitions to a fully insulating state, while in the unwelded areas, the remaining Ag thin film serves as an electrode without transitions. Mathematical modeling and heat transfer simulations were conducted to examine the laser energy transfer mechanism and determine the optimal thickness of the Ag thin film. Laser scan paths were designed for the Joule heating microheater and generated for subsequent selective laser welding. The designed microheater was fabricated and hermetically packaged between the glass substrates. Finally, a reusable cell culture tester was fabricated to demonstrate the practical applicability of the packaged glass microheater. The prototype was directly applicable to cell culture without requiring additional packaging. Moreover, it demonstrated consistent heating performance even after washing for reuse, indicating its feasibility for reusable devices. These results indicate that the proposed selective laser welding process, demonstrating the potential for advancing micropatterning and packaging technologies with diverse applications, is a promising approach for manufacturing packaged microdevices.