Implantable SiC based RF antenna biosensor for continuous glucose monitoring

A continuous glucose sensor employing radio frequency (RF) signals has been developed using the biocompatible material Silicon Carbide (SiC). Unlike biosensors that require direct contact with interstitial fluids to trigger chemical reactions to operate, this biocompatible SiC sensor doesn't require a direct interface. The sensing mechanism is based upon a shift in resonant frequency as a function of change in glucose levels which electrically manifests itself as a change in blood permittivity and conductivity. For invivo applications the antenna sensor needs to operate inside the body environment, and it has been determined that the best operational location of this biocompatible SiC biosensor is within fatty tissue in close proximity to blood vessels. To test the sensor as a function of glucose level, measurements using synthetic body fluid (SBF), which is electrically equivalent to blood plasma, and pig blood were performed. Changes in sensor performance to varying glucose levels were measured and a shift in resonant frequency to lower values observed with increasing glucose level. In-vitro sensor performance demonstrated that the sensor showed a dose dependent response to glucose concentration from 120 mg/dl to 530 mg/dl. A shift of 40 MHz and 26 MHz for blood mimicking liquid and pig blood was observed corresponding to 97 KHz and 67 KHz shift per 1 mg/dl change in blood glucose.