Session: 04-07-01: Material Processing of Flexible/Emerging Electronics, Sensors, and Devices

Paper Number: 173930

Pressure-Tolerant, Miniature Ocean Sensing Tag With Acoustic Telemetry for Real-Time Ctd Monitoring 

Real-time monitoring of the ocean’s physical, chemical, and biological properties enables instantaneous oceanographic analysis and timely decision-making in maritime operations, such as commercial shipping, fishing, and naval activities. Conductivity, temperature, and depth (CTD) measurements are particularly critical, as they provide fundamental data for understanding ocean biogeochemistry, determining seawater density, and supporting both ocean current modeling and  weather forecasting. To collect CTD data globally, CTD profilers have been deployed on various ocean observation platforms for over a decade, including profiling floats, rosette samplers, and  autonomous underwater vehicles (AUVs). However, existing CTD devices face several challenges for real-time monitoring and deep-sea investigation, including their bulky, heavy structures due to metallic protective housings, limited underwater communication capabilities, and high energy consumption of CTD sampling platforms. With emerging advances in soft electronics, a flexible CTD sensing system (Marine Skin) integrating metallic thin-film sensors and conformal packaging has been developed. Its wearable and lightweight (3 g) design enables noninvasive bio-tagging of small fish species, such as seabream. Although the device demonstrated sustained performance when tested under lab-simulated harsh conditions, including hydrostatic pressure (3000 psi, ≈2 km), mechanical deformation (cyclic bending), and prolonged exposure to Red Sea water (28 days), its capability for real-time CTD monitoring has not been thoroughly assessed. Specifically, only continuous depth recordings have been reported, and these tests were limited to a lab-controlled environment at a depth of 70 cm for up to 6 minutes. Moreover, the system relies on Bluetooth for wireless communication, which becomes ineffective underwater due to the rapid attenuation of electromagnetic signals, allowing data transmission only when the animal surfaces. While soft electronics offer an alternative without pressure housings, their functionality and commonly used wireless electromagnetic communication are ineffective in harsh underwater environments. Here, we present an ocean sensing tag that integrates soft, pressure-tolerant conductivity, temperature, and depth (CTD) sensors with a miniaturized circuit that converts CTD measurements into voltage signals and drives an acoustic transducer for underwater data transmission. The miniature tag measures 17 mm × 20 mm × 7.5 mm and weighs only 4.90 g, enabling deployment on diverse, energy-efficient platforms, including noninvasive fish tagging. The CTD sensors maintain reliable performance at hydrostatic pressures up to 15 MPa, allowing direct operation at depths of 1,500 meters. Field testing in the Pacific Ocean validates the system’s capability for wireless, real-time CTD monitoring, achieving accurate CTD sensing comparable to a commercial sensor and an 89.26% detection efficiency for acoustic transmission. This work highlights a pressure-resilient, compact ocean sensing system that seamlessly integrates soft electronics and acoustic telemetry to advance global ocean observation and deep-sea exploration. 

Presenting Author: Xueju Sophie Wang University of Connecticut

Presenting Author Biography: Dr. Xueju ‘‘Sophie’’ Wang is currently an Assistant Professor in Materials Science and Engineering and affiliated with Mechanical and Biomedical Engineering and the Institute of Materials Science at the University of Connecticut. Her research interests lie in the intersection of soft, stimuli-responsive materials, mechanics, and multifunctional structures/electronics for applications from soft robotics to biomedical devices. Dr. Wang has received several awards, including the NSF CAREER Award (2022), the NIH Trailblazer Award (2022), the Office of Naval Research (ONR) Young Investigator Award (2023), the ASME ORR Early Career Award (2022), the ACS Polymeric Materials: Science and Engineering (PMSE) Young Investigator Award, the ASME Haythornthwaite Foundation Research Initiation Award, the Extreme Mechanics Letters (EML) Young Investigator Award (2022), and Soft Matter Emerging Investigator.

Authors:

Xueju Sophie Wang University of Connecticut