Strategies for the implementation of a simple, implantable sensor across different in vivo applications

The resonant behavior of passive sensor systems are affected electrical properties of nearby materials. Encapsulation of passive sensors allows them to be deployed across a wide range of applications without the need for significant redesign. The effects of different materials and media in close proximity to the sensor were compared between a sensor before and after encapsulation. The thickness of the encapsulating layer, (1.0 mm), was determined by defining the distance at which the change in resonant behavior reduced to 10% of the original value. Encapsulation reduced the variability and magnitude of the changes to the resonant frequency of the sensor induced by the surrounding media by 72% and 70% respectively. It also increased the average signal strength by 85% and reduced variability in signal strength between all treatments by 73%. Encapsulation resulted in a significant improvement of sensor performance and consistency across a range of media and packaging. Future work includes the incorporation of these findings into the batch fabrication process and the investigation of the effect of encapsulation using higher permittivity capping layers.