Parylene-oil-encapsulated low-drift implantable pressure sensors

This paper demonstrates a parylene-oil-encapsulated packaging technology that applies to commercial pressure sensors to enable intraocular pressure sensing with minimal drift. Commercial digital-output barometers are chosen to be packaged first with 100,000 cSt silicone oil and then sub-micron thick parylene within the volume of the original housing. It is newly found that parylene type and oil viscosity can decide the sign and magnitude of the intrinsic stress in parylene. Additionally, the effect of deposited thickness and temperature on film stress is studied through induced pressure offset. When properly designed, parylene-oil-encapsulated pressure sensors maintain <0.3% sensitivity drift and