Structural design and simulation of PDMS/SiC functionally graded substrates for applications in flexible hybrid electronics

Flexible hybrid electronics possess significant potential for applications in biomedical and wearable devices due to their advantageous properties of good ductility, low mass, and portability. However, they often exhibit a substantial disparity in elastic modulus between the flexible substrate and rigid components. This discrepancy can result in damage to the rigid components themselves and detachment from the substrate when subjected to tensile, bending, or other loads. Consequently, it diminishes the lifespan of flexible hybrid electronics and restricts their broader-scale application. Therefore, this paper proposes a polydimethylsiloxane (PDMS)/SiC functionally graded flexible substrate based on variable stiffness properties. Initially, ABAQUS simulation is employed to analyze how variations in stiffness impact the stress-strain behavior of PDMS/SiC functionally graded flexible substrates. Subsequently, we propose a multi-material 3D printing process for fabricating PDMS/SiC functionally graded flexible substrates and develop an advanced multi-material 3D printing equipment to facilitate this process. Tensile specimens with the functional gradient of PDMS/SiC are successfully fabricated and subjected to mechanical testing. The results from the tensile tests demonstrate a significant enhancement in the tensile rate (from 21.6% to 35%) when utilizing the PDMS/SiC functionally graded flexible substrate compared to those employing only PDMS substrate. Furthermore, the application of PDMS/SiC functional gradient flexible substrate exhibits remarkable bending and tensile properties in stretchable electronics and skin electronics domains. The integrated fabrication approach of the PDMS/SiC functionally graded flexible substrate structure presents a novel high-performance solution along with its corresponding 3D printing methodology for stretchable flexible electronics, skin electronics, and other related fields.