Design and optimization of pressure-tolerant flexible systems under extreme hydrostatic pressure

Soft robots have been increasingly developed and deployed for deep-sea applications in recent years. Unlike traditional underwater robots that rely on bulky pressure vessels for protection, some soft robots can be directly exposed to hydrostatic pressure utilizing a polymer-encapsulation approach. This approach optimizes the structure of electronic components in soft robots to eliminate high-pressure interfaces, yet clear design guidelines remain absent due to its complexity. This paper introduces a design methodology for pressure-tolerant electronics; that leverages the Eshelby inclusion theory and finite element analysis. A parameter κ called the geometric coherence index for numerical optimization is proposed to evaluate the arrangement of PCB components. Calculations and simulations have demonstrated that the optimized circuit board components exhibit a reduction of up to 45.5 % in both maximum and average shear stress under high hydrostatic pressure. A circuit board prototype has been manufactured and then tested at a depth of 10,900 m in the Mariana Trench. Field tests have confirmed the effectiveness of this method, demonstrating its potential for improving deep-sea exploration technologies.