Ultra-flexible micro-antennas on PDMS substrate for MRI applications

In this paper, we present the development of ultra-flexible micro-antennas dedicated to MRI on small rodents. Their design is wireless and based on transmission lines into a dielectric material i.e. PDMS. To overcome the weak adhesion of metal to this polymer surface, we have developed a new fabrication process using transfer technology. This process avoids contact of PDMS with chemicals to preserve the bulk properties. An accurate alignment of conductor lines and a high transfer yield are obtained. The electromagnetic characterization of the antennas validates the reliability of the process. Bending the structures up to a radius of 2 mm does not mechanically alter the copper lines. In these conditions, only a small decrease of f₀ (less than 1%) and no change in Q factor are observed. MRI micro-antennas are just an example of application for the developed process which can be used for fabrication of various metallic structures on PDMS.