Stretchable array of ISFET devices for applications in biomedical imagers

Technologies for rendering of 2D arrays of ISFET (Ion Sensitive FET) devices into stretchable and biocompatible systems with applications in biomedical imagers are presented. Rigid silicon segments containing the ISFET devices are mechanically and electrically connected through flexible parylene beams with embedded metal tracks for signal and power distribution. Key in this technology is the use of biocompatible parylene polymer both as a structural element for the stretchable-interconnect beams, as well as for the overall system encapsulation. Local laser ablation of the parylene coating is successfully applied on the fabricated ISFET devices to expose the ion-sensitive ISFET gates resulting in a leakage current in the nA range. The ISFET devices are fabricated using a custom 2 µm CMOS process. ISFETS are processed successfully side by side with CMOS devices to verify their compatibility.