Foil level packaging of a chemical gas sensor
A generic method for the packaging of transducers at the foil level is proposed and was demonstrated on chemical gas sensors made on a plastic foil. The processing was based on the lamination of pre-patterned polymeric structures on the fabricated devices and covered by a gas permeable membrane. This polymeric packaging can be either applied on plastic foils or on conventional substrates such as silicon or glass. It can be used when standard packaging techniques might not be applied or when they can represent a significant cost. Using the lamination of a foil, the dry process presented here is compatible with large-scale fabrication techniques, such as roll-to-roll processing, and aims at reducing the global fabrication cost of sensing devices made on a plastic foil. It can further lead to the fabrication of all polymeric devices. This generic processing can be used for a wide range of applications in the field of microsystems, especially for which the foil level is required and where standard techniques at the wafer level are not applicable. The foil level packaging (FLP) was implemented here for the encapsulation of gas sensors on a plastic foil and validated through gas measurements.