Vacuum cavity formation for high thermal isolation in flexible thermal sensor

For producing a variety of flexible MEMS sensors, we previously developed a process that uses a Cu On Polyimide (COP) substrate as a starting material and sacrificial Cu etching to produce a cavity and electrical feed-through structures on the substrate [1]. In the current study, we introduced a vacuum cavity realizing high thermal isolation in a flexible thermal sensor, for the first time. Parylene thickness as a function of the amount of dimer usage was studied, and a preliminary experiment exploring the fabrication of the vacuum cavity structure was performed. These results, demonstrate that we successfully produced a vacuum cavity in the thermal sensor. To determine the effect of the thermal isolation by vacuum cavity to thermal sensor, we applied it to a flow sensor, and found that we can reduce the response time to one-half by introducing the vacuum cavity in thermal sensor.