A small implantable dual band biocompatible antenna for medical wireless telemetry applications

Small antennas are absolutely essential for implantable medical telemetry systems since they dictate the overall size of the system. Earlier, we designed a miniaturized implantable antenna based on the leaky wave properties of the wave travelling along the interface (which happens in case of a slot along the interface) between two different dielectric media. The leaky wave is radiated in the medium with higher wave number. The property is extremely useful for implantable antennas since the dielectric properties of biological tissues are extremely high. The designed antenna had dimensions of 10mm × 12 mm × 1mm and was printed on FR4 substrate. This antenna is not biocompatible and it can be made so by coating the antenna with biocompatible materials like silica (ε_r=3.8). Coating the antenna with permittivity less than FR4 does not produce leaky waves and hence no radiation. This problem can be averted by coating the antenna with a higher permittivity biocompatible material. The additional layer complicates the antenna design in addition to increasing the size of the implant.