Trace Polymer-Bonded carbon nanotube networks for precise strain sensing in healthcare

• Trace polymer bonded-CNT networks with high conductivity and mechanical stability . • Stretchable strain sensors with linear response and a low detection limit of 0.0024%. • The sensor is hysteresis-free, pressure-insensitive, robust for underwater operation. • Precise cuff expansion monitoring of tracheal tubes for better healthcare. • Real-time monitoring of the swallowing-respiration coordination. Stretchable sensors that can provide precise strain measurements have a paramount impact on applications ranging from healthcare, biomedical engineering, and soft robotics to human–machine interactions. However, developing simple resistive strain sensors that meet all the requirements for real-world applications remains challenging. This work presents trace polymer-bonded carbon nanotube (TP-CNT) networks for high-performance stretchable resistive strain sensors. Owing to the trace polymer bonding between CNTs, the networks exhibit both good mechanical stability and electrical conductivity. Crucially, the TP-CNT strain sensor shows a linear response up to 100% strain, with an extremely low detection limit of 0.0024% and negligible hysteresis. Further experiments reveal that the TP-CNT sensor is insensitive to pressure loading and is robust for underwater operation. We demonstrate that a TP-CNT sensor can precisely monitor the expansion of a tracheal tube cuff and recognize the critical pressure point where the cuff is in good contact with the tracheal wall. Moreover, sensors can be worn on the skin to monitor the coordination between swallowing and respiration for the assessment of deglutition disorders. In summary, TP-CNT sensors can be easily fabricated in batches with consistent characteristics and accurate strain sensing capabilities, making them promising for practical applications in healthcare.