Flex-to-Rigid (F2R): A Generic Platform for the Fabrication and Assembly of Flexible Sensors for Minimally Invasive Instruments

The flex-to-rigid (F2R) platform allows for the fabrication of miniature and flexible sensor assemblies for minimally invasive medical instruments such as catheters and guidewires. Devices fabricated on silicon wafers are transferred onto polyimide and partially rendered flexible by means of a two-step backside silicon deep reactive ion etching. The flexibility allows for the devices to be folded into, or wrapped around the tip of the instruments. The fabrication of the whole assembly is based on standard integrated circuit manufacturing technologies so that it is possible to scale the devices down to the dimension of the smallest guidewires. Several demonstrations are presented to show the versatility of the F2R technology, and a polyimide-based flexible thermal flow sensor for application at the tip of a 360- μm diameter guidewire is introduced.