The unique environment of the hadal zone has created material circulation patterns and biological gene characteristics. Microbes play an irreplaceable role in the ocean ecological environment and material circulation due to their pervasiveness, abundance, and metabolic diversity. In this paper, we designed and developed a microbial sampling device that can be used in a depth of 10,000 m, with its working parts suitable for the full-sea depth. The multi-stage membrane realized the in situ multi-stage filtrations. The samples were in situ fixedly preserved by RNAlater storage solution. At the same time, we modeled and calculated the multi-stage membrane separation and filtration process, simulated the interception phenomenon of particles with different sizes passing through the multi-stage membrane area, and explored the influence of varying inlet velocities. A multi-stage membrane separation and filtration test system was built. The operational characteristics of different filters were compared and analyzed, and the appropriate filter material was selected according to the flow capacity and physical properties. A 100 MPa high-pressure test was carried out to check the device’s performance under a high-pressure environment. The sampler prototype was constructed and tested in the Mariana Trench. The results indicated that the device could work at the deepest point of the Mariana trench.

Marine sediments are rich in mineral resources, organic resources, and microbial life. The study of marine sediments is of great significance for the development and utilization of marine resources and understanding the life process. Resistivity is the overall characteristic of the electrical conductivity of marine sediments. Measuring the resistivity of marine sediments is helpful to ascertain the marine geological structure, study the distribution of marine mineral resources, and evaluate the marine soil environment. Measuring the resistivity of marine sediments is of great significance to promote marine exploration. At present, the resistivity measurement device on the market can be directly used to measure soil and water on land, but if used to measure marine sediments, it will be disturbed by seawater temperature and pressure, resulting in large errors. In this paper, a high-precision pressure-maintaining transfer system of marine sediment resistivity measurement instrument based on circular permutation electrode is designed, which can measure the resistivity of marine sediment samples after pressure-maintaining transfer. At the same time, a new type of circular permutation electrode measurement method is proposed, which makes the resistivity value more accurate, reduces the length of the probe appropriately, and saves the cost. By measuring the resistivity of marine sediments, the type of sediments can be inverted, which provides a way of thinking about the promotion of the research and development and utilization of marine resources.