Biocompatible encapsulation of CMOS based chemical sensors

One of the most challenging design aspects of chemical sensors is the isolation of the non-sensitive areas from the sensed medium. This becomes particularly critical in applications where the sensors are part of an implantable platform, restricting the available options to those using biocompatible materials. Parylene has been extensively used to coat pacemakers as it demonstrates excellent chemical, electrical and thermal stability. In this work, we have utilized parylene to encapsulate CMOS-based chemical sensors bonded on a cartridge, while the sensing area has been exposed by laser ablation and sonication. Measured results demonstrate improved electrical isolation than previously reported techniques.