Improved self-sealing liquid encapsulation in Parylene structures by integrated stackable annular-plate stiction valve

We report on an improved self-sealing structure for Parylene-based liquid encapsulation. The specific improvements are an integrated stiction valve which reduces overall device footprint by nearly 50% over in-plane designs and the use of an annular-plate design in a stackable multi-layered configuration for successful longterm liquid encapsulation. We achieve automatic wafer-level liquid entrapment without using adhesives or processing at elevated pressures or temperatures. We also demonstrate the use of electrochemical impedance measurements as a means for tracking internal liquid volume.