Piezoresistive polymer composites based on polyether block amide and carbon nanotubes for self-sensing medical urinary catheters

There is a large current need for new and improved approaches to treat chronic diseases such as non-neurogenic bladder diseases, the solution to prevent urethritis or inflammation of the urethral meatus being to slide a catheter along the urethra. In order to improve this procedure, it would be advantageous to place sensors in the catheter, allowing to monitor forces and deformation along the process. This work reports on a new generation of functional, sustainable piezoresistive sensors for their implementation in catheter medical devices. Composite films based on polyether block amide with varying contents of multiwalled carbon nanotubes (MWCNTs) as fillers have been produced with MWCNT contents up to 5 wt%. Further, their morphological, thermal, mechanical, electrical and piezoresistive functional response have been evaluated. Composite materials with suitable filler dispersion have been obtained, with a maximum electrical conductivity of 9 x 10(-3) S.m(-1) for the samples with the highest filler content of 5 wt% of MWCNT, the percolation threshold is between 1 and 2 wt% MWCNT content. All composites show appropriate piezoresistive behavior, with the gauge factor (GF) ranging between 0.5 and 1.5. At a maximum deformation of 5 mm, a composite with 3 wt% of MWCNT dip-coated on a catheter demonstrates an exceptional GF similar to 4.5. Additionally, an electrical system was developed to demonstrate the suitability of the self-sensing catheter for practical applications, by detecting bending deformations in real time. This work shows that these sustainable polymer-based nanocomposites can be used in the biomedical industry due to their excellent piezoresistive characteristics.