Ultra-flexible devices for 360 μm diameter guidewires

We report on the mechanical and electrical integrity of an ultra-flexible polyimide-based sensor platform for minimally invasive medical instruments. Aluminum structures placed in the stress neutral plane, the tensile plane or a combination of both are fabricated and tested under bending down to 300 μm diameter. The obtained results provide design rules for ultra-flexible flow sensors to be implemented in 360 μm diameter guidewires, while keeping direct contact with the surrounding environment. The need for design rules is further supported by simulations made using an analytical model especially developed for stress-strain modeling in flexible devices with externally applied bending.