Liquid encapsulation by Bonding-in-Liquid Technique

We propose and demonstrate Bonding-in-Liquid Technique (BiLT) for encapsulation of liquid in MEMS devices. Liquid encapsulation enables innovative MEMS devices with various functions. Interfusion of air bubbles, heterogeneity of the liquid quantity, and leakage of the encapsulated liquid must be averted not to deteriorate device performances. In BiLT, two structural layers are passively aligned and brought into contact in solution, where the encapsulation cavities are uniformly filled up with the liquid without air bubbles. A UV-curable resin is used as an adhesive that does not require heat or vacuum environment but UV to bond the two layers. We successfully achieved encapsulation of DI water and glycerin in silicon structural layers. Since conventional aligners are not applicable to BiLT, we experimentally evaluated the accuracy of the passive alignment process in solution that makes use of matching concave and convex structures.