Study on the control of mechanical and electrical properties of 3d printed BTO/PDMS flexible porous composites

Flexible piezoelectric functional composite materials have the advantages of strong plasticity and good surface adhesion, and show great potential in smart wearable devices, electronic skin and other applications. However, due to the complexity of traditional preparation process, high molding cost and poor air permeability, its further development is limited. Direct ink writing (DIW) 3D printing technology is a rapid prototyping technology, with higher flexibility, faster manufacturing speed and lower manufacturing costs, is widely used in metal, ceramic and composite material molding. In this work, a ink system with polydimethylsiloxane (PDMS) as binder and barium titanate (BTO) ceramic powder as piezoelectric filler was developed, the printing work of flexible porous BTO/PDMS composite material was completed. DIW dual-nozzle printing technology was applied to realise "electrode-piezoelectric-electrode" integrated flexible porous functional gradient structure composites in this study. The results show that the BTO/PDMS ink has the characteristics of shear thinning. When the nozzle diameter is 0.5 mm, the printing speed is 650 mm/min, and the BTO mass fraction is 80%, the flexible porous piezoelectric composite with high precision and complex structure is printed. By phase analysis of BTO/PDMS, it is found that the sample has the characteristic peak of BTO. The microstructure analysis shows that the surface of the sample has good structural fidelity and there are a few island-like pores in the interior. The mechanical test shows that the maximum tensile strength of the sample is 1.33 MPa, the elastic modulus is 1.72 MPa, the longitudinal piezoelectric coefficient d33 is 4.37 Pc/N, and the open circuit voltage VOC is 3.17 V. This work demonstrates an attractive method of moulding flexible piezoelectric materials with an "electrode-piezoelectric-electrode" structure, which provides a reference to current 3D printing flexible material fabrication techniques due to its simplicity of operation, time and manufacturing cost savings.