High performance strain sensors based on chitosan/carbon black composite sponges

Highlights: • Conductive chitosan (CS)/carbon black (CB) composite sponges were prepared by solution-mixing and freeze-drying. • CB can form a continuous filler network in CS matrix. • CB increased the electrical conductivity, compressive properties, and thermal stability of CS sponges. • CS/CB composite sponges can detect various human activities such as pronouncing and breathing. Chitosan (CS)/carbon black (CB) composite sponges with high electrical conductivity and strain sensing sensitivity are prepared by combining solution-mixing and freeze-drying techniques. CB nanoparticles with diameter of ~ 40 nm play the role of a conductive component in the CS/CB composites. CB can form a continuous filler network in CS, which leads to the increase in viscosity and shear modulus. When writing and drying the CS/CB conductive ink, conductive tracks are obtained. With the increase in CB content, the density, electrical conductivity, compressive properties, and thermal stability of CS sponges are improved. The X-ray diffraction and Fourier transforms infrared spectroscopy results show CB are successfully compounded into CS matrix. The addition of CB leads to a slight decrease in the porosity of CS sponges. Sensing performances of CS/CB composite sponges are investigated by detecting various human activities including pronouncing, breathing, and joint bending. CS/CB composite sponges show good sensitivity and stability after several hundred loops. CS/CB composite sponges combine the advantages of low-cost, easy fabricating process, flexible, and high performance, which make them show great potentials in highly sensitive strain sensor.