Laser-induced hierarchical carbon patterns on polyimide substrates for flexible urea sensors

Abstract

Highly sensitive urea sensors can now be made with direct infrared laser writing on cheap Kapton sheets A collaborative international team led by Dr. Swati Sharma from Karlsruhe Institute of Technology, Germany demonstrates the first catheter-compatible, pH-based enzymatic urea sensor. The authors directly convert commercially available Kapton films into carbon using IR laser, and optimize the process for obtaining a high surface area material with hydrophilic functional groups for biosensor fabrication. These inexpensive flexible sensors are fabricated by enzyme absorption on to the carbon films, with or without an electrodeposited intermediate chitosan layer. They can be rolled-up to fit inside a catheter tube, and feature detection limit down to 10−4 M urea concentration that is 100 times lower than that in the blood serum of a healthy human. These sensors show promising applications as they are inexpensive, flexible, readily usable for in-vivo urea determination and easily extendable to multi- functional circuits.