Flexible and multifunctional magnetoelectric sensor for real-time monitoring of electrical and mechanical failures in submarine cables based on PLLA/BBPPE/CFO composites

Abstract

Submarine cable accounts for benthonic power and data transmission, whose failure can cause huge economic losses and environmental pollution. The failure of submarine cable is mostly electrical failures due to external mechanical damage under complex and variable submarine environment. Thus, the real-time monitoring of electric and mechanical abnormal signal of submarine cable is critical. However, current individual sensors show certain limitations considering the limited space and curvature shape of submarine cable. Besides, shocks from ocean currents or biological activities often lead to misjudgment from sensors. In the present work, Poly (L-lactic acid) is selected as matrix due to its heat-resistant piezoelectricity, which is further blended with cobalt ferrite to serve as magnetoelectric composites. Meanwhile, a piezoelectric elastomer (BBPPE) with low elastic modulus and high piezoelectricity is synthesized and added into the blends to significantly improve its piezoelectricity and interfacial coupling, which eliminates the stress transfer loss between the interface to provide excellent magnetoelectric properties. Thus, a flexible and multifunctional magnetoelectric sensors is proposed to real-time and synchronous monitor electrical and mechanical failures in submarine cables. The PLLA/BBPPE/CFO10 magnetoelectric current sensor (PLLA/BBPPE/CFO10 MCS) presents excellent piezoelectric response time (10 ms) and sensitivity (5.03 mV kPa⁻¹), superior tensile strength (17.9 MPa) and magnetoelectric response linearity (>0.99), with current sensitivity of 7.817 mV A⁻¹ and an accuracy of ±10 mA. Meanwhile, the low Tg of BBPPE and the high Curie temperature of CFO ferrite enable the PLLA/BBPPE/CFO10 MCS to work with a wide temperature ranging from −5 °C to 150 °C to satisfy the undersea service. The PLLA/BBPPE/CFO10 MCS can be encapsulated inside submarine cables to realize real-time monitoring and early warning of mechanical shocks and current variations, which demonstrates great potential in submarine cable safety monitoring.