在深海原位环境下精确捕获和收集单个目标微生物是当前深海微生物研究中的一大挑战。设计了一个应用在深海环境中的光镊捕获系统方案，系统包含光镊模块、微流控芯片、耐压外罩等部分，可实现原位捕获收集深海微生物。建立了位于南海北纬18°附近，1.5 km深处的海水折射率模型，预估了深海对光镊系统激光功率的损耗。使用T矩阵法计算对比了光镊在深海中和陆地上的纯水中对不同折射率和不同大小的球形微生物的捕获力。结果表明，相比于纯水中，光镊在1.5 km的深海中的最大轴向捕获力平均降低了25%，最大横向捕获力平均降低了20%。本研究可为未来基于光镊技术开发的深海微生物分选设备的下海实验提供参考。

A significant hurdle in current deep-sea microbial research remains the inability to capture these microbes in their natural habitat. Optical tweezers, with their non-contact, low-damage, and highly precise capabilities, present an ideal solution for capturing and manipulating microorganisms in liquid environments, showing promise in capturing deep-sea microbes. However, existing research on optical tweezers primarily focuses on ideal mediums such as pure water and air, with few studies exploring their application and the alteration of trapping force characteristics in the deep-sea environment.In order to address the challenge of accurately capturing and collecting deep-sea microorganisms, this paper presents a designed optical tweezers acquisition system tailored for deep-sea environments. The system incorporates an optical tweezers module, a microfluidic chip, and a pressure-resistant cover, facilitating the in-situ capture and sorting of deep-sea microorganisms. In examining the alteration of trapping force in optical tweezers in deep-sea conditions compared to pure water, this study initially outlines the principle and methodology for calculating trapping force using the T-matrix method. Subsequently, it investigates the factors influencing optical tweezers' trapping power in the deep-sea environment, including changes in seawater's refractive index and light wave attenuation. To achieve this, a refractive index model for seawater at 1.5 km north latitude of 18° in the South China Sea is established, and the attenuation coefficient of seawater to light waves is estimated based on prior research data. Furthermore, under consistent experimental parameters, the study employs the T-matrix method to calculate the trapping force of Gaussian optical tweezers in both deep-sea conditions and pure water. This aims to capture spherical microorganisms of varying sizes and refractive indices, assessing the decrease in trapping force of optical tweezers in the deep-sea compared to pure water.Our experimental findings reveal that the shape of the dispersion curve of seawater at 1.5 km is almost the same as that of pure water on land, indicating a relatively gentle curve and an Abbe number exceeding 55, indicating minimal dispersion in seawater. Notably, compared to pure water, the refractive index of seawater is slightly higher, measuring 1.34 at a wavelength of 785 nm, a marginal increase from pure water's 1.33. At this juncture, the attenuation coefficient of seawater stands at approximately 2.3 m^-1, resulting in a 92% transmittance through a 3.5 mm thick seawater layer. The study calculates the optical forces exerted by optical tweezers on spherical microorganisms with radii of 1 μm, 3 μm, 5 μm, and 10 μm in both the 1.5 km deep-sea environment and a pure water environment, with refractive indices of 1.35, 1.4, and 1.5, respectively. The findings indicate an average decrease of approximately 25% in maximum axial capturing force and about 20% in maximum transverse capturing force in the deep-sea environment compared to pure water on land. This emphasizes the greater influence of the increase in the medium's refractive index surrounding the target on the axial capturing force than on the transverse capturing force. Notably, these optical tweezers experiments employed the same laser power. Considering the greater attenuation of laser power in the deep-sea compared to pure water, the maximum trapping force of optical tweezers is proportional to the attenuation amplitude of the laser power.In summary, this study applies optical tweezers technology to in-situ capture deep-sea microorganisms, extending the technology's application domain. Additionally, it represents a comprehensive exploration of optical tweezers' functionality in a distinctive and demanding environment. These findings could serve as a valuable reference for future experiments developing deep-sea microbial sorting equipment utilizing optical tweezers technology.