Preparation and property of cellulose electrospun nanofibers-based flexible epidermal electrodes

Objective In order to solve the problems of bio-incompatibility and low response integration of current wearable electrode materials, cellulose electrospun nanofiber based flexible epidermal electrode was prepared by natural cellulose as raw material, combining novel dissolution technology and electrospinning technology, and then in situ polymerizing conductive polymers. The electrode application in the field of human electrical signal monitoring was explored.

Method Cellulose was dissolved in a novel ionic liquid composite solvent to construct a low-viscosity, long-term stable spinning solution. The regenerated cellulose-based electrospun nanofibers were prepared by room-temperature electrospinning combined with pre-coagulation process. Then, they were composite with poly (3,4-ethylenedioxythiophene) - poly (styrene sulfonate) (PEDOT:PSS) for nano-self-assembly to obtain flexible epidermal electrodes. The scanning electron microscopy, automatic specific surface and porosity analyzer, C101 gas penetration test system, Fourier transform infrared spectrometer, and X-ray diffractometer were used to characterize the morphology and chemical structure of the electrodes. The universal material testing machine was used to test the tensile properties and adhesion of electrodes. The electrochemical workstation was used to detect electrode impedance. The electromyography and electrocardiogram were monitored by dual conductivity muscle electrical module and multi-channel physiological signal acquisition system.

Result The cellulose electrospun nanofibers based flexible epidermal electrode had an ordered network and rich pore structure, presenting a cellulose Ⅱ crystal structure. When the volume fraction of PEDOT:PSS was 20%, the tensile properties and adhesion of the electrode were optimal, that is, the strain was 9.8%, the Young’s modulus was 0.04 MPa, and the adhesion force to glass and pigskin (17.8 and 14.7 N/m, respectively) was high. The electrode exhibited a low contact impedance of electrode-skin in the range of 10⁻²−10⁵ Hz. Moreover, it can generate high-quality electromyography and electrocardiogram signals.

Conclusion A wearable electrode with flexible, breathable, self-adhesive, and low impedance is prepared by natural cellulose and conductive materials as main components. The electrode can be used for human electrical signal monitoring, providing technical support for the construction of biocompatible cellulose-based wearable electrode materials.