Printable piezoresistive polymer composites for self-sensing medical catheter device applications

There is a constant demand for new and/or improved health treatments that require flexible sensor devices. This is particularly relevant in relation to neurogenic bladder dysfunction. In this context, polymer composites have been developed based on three different matrices, carboxymethyl cellulose (CMC), styrene-ethylene/butylene-styrene (SEBS) and polyvinyl alcohol (PVA), with different concentrations of multiwalled carbon-nanotubes (CNT) filler contents for catheter medical device application. The mechanical properties of the nanocomposites are critically dependent on the polymeric matrix and also depend on CNT content with maximum strain is about 4%, 100% and 700% for CMC, PVA and SEBS materials, respectively. Electrical conductivity increases near 10 orders of magnitude up to 0.11 S/m for PVA with 5 wt percentage (wt.%) of CNT, one magnitude order than the most filled PVA and CMC composites. The percolation threshold (fc) of the composites are fc = 3 wt% for CMC, fc = 2 wt% for SEBS, and fc = 1 wt% for PVA as polymer matrices. Furthermore, the functional performance of the composites is characterized by the piezoresistive response, with a gauge factor (GF) ranging between 1 and 6 for the different composites. Finally, a self-sending catheter device was developed as a proof-of-concept, based on a PVA composite with a GF∼1.5. demonstrating proper adhesion and excellent sensing behavior at bending up to 7 mm. Thus, it is demonstrated that screen-printable piezoresistive sustainable composites can be developed for medical application with excellent electrical and mechanical properties.