Single-cell research can reveal cellular heterogeneity, functional diversity, and disease-related mechanisms, making it an important foundation for precision diagnostics, drug development, and personalized therapy. A complete single-cell workflow usually includes initial single-cell screening, isolation, and manipulation, followed by downstream genomic, proteomic, metabolic, mechanical, and functional analyses. In recent years, techniques such as limiting dilution, micromanipulation, laser capture microdissection, fluorescence-activated cell sorting, microfluidics, and optical tweezers have continued to develop, but each still has limitations in throughput, operational flexibility, cell damage, equipment cost, labeling dependence, or integration with downstream analysis. "In contrast, optoelectronic tweezers (OETs) use dynamic optical patterns to create virtual electrodes on a photoconductive layer and manipulate single cells through dielectrophoretic forces, offering a noncontact, low-damage, programmable, and high-throughput approach. OETs therefore show unique advantages in cell capture, transport, sorting, patterning, analysis, and functional screening." said the author Weiguo Cui, a researcher at Capital Medical University, "For this reason, it is important to systematically review the technical principles, device development, multitechnology integration, and single-cell applications of OET, while also discussing its potential and future challenges in antibody discovery, cell line development, tumor immunology, and cell therapy."
The core principle of optoelectronic tweezers (OETs) is to use dynamic optical patterns to create reconfigurable "virtual electrodes" on a photoconductive layer, generating nonuniform electric fields in a liquid environment and enabling noncontact manipulation of single cells, microparticles, and nanostructures through optically induced dielectrophoresis. A typical OET system consists of a light source, power supply, photoconductive chip, and imaging system. In the dark, the photoconductive layer has high impedance and the electric field in the liquid layer is weak; when a selected region is illuminated, the conductivity of the photoconductive layer increases, strengthening the local electric field and allowing target cells to be trapped, transported, sorted, or patterned. In addition to dielectrophoretic force, AC electroosmosis, electrothermal flow, and electrophoresis may also contribute under different frequencies, media, and device configurations. As the technology has developed, OET devices have been optimized in terms of light source, photoconductive layer, power supply, and electric-field direction. Examples include replacing conventional digital micromirror projection with LCD, grayscale-image, and laser-interference schemes; improving photoconductive layers with PEG coatings, lipid bilayers, dual photoconductive layers, patterned structures, phototransistors, and organic photoconductive materials to reduce cell adhesion, thermal damage, resolution limits, and medium restrictions; and developing self-powered OET, lateral-field OET, and combined vertical–lateral electric-field designs. These advances have transformed OET from an early light-controlled micromanipulation tool into a more flexible, low-damage, and highly integrable platform for single-cell research.
In single-cell research, the value of OET lies not only in moving cells, but also in connecting screening, manipulation, and analysis on the same platform. Because different cells vary in size, membrane integrity, dielectric properties, and motion responses, OET can use dielectrophoretic forces generated by dynamic optical patterns to identify live and dead cells, separate tumor cells from leukocytes, and screen sperm or oocytes. When integrated with microfluidics or optoelectrowetting, OET can also encapsulate target cells into microdroplets or microchambers for subsequent culture and analysis. Beyond sorting, programmable optical patterns allow OET to arrange cells into defined spatial patterns, supporting studies of cell adhesion, migration, interaction, and tissue-like organization. At the analytical level, OET can help construct controlled cell–cell contact systems, such as observing immune killing between natural killer cells and target cells, and can be combined with locally enhanced electric fields to achieve cell pairing, fusion, electroporation, gene transfection, and selective lysis. In addition, OET can measure label-free single-cell physical parameters such as mass, density, membrane capacitance, and membrane conductance, and can manipulate biomolecules such as DNA, proteins, and polysaccharides through light-controlled concentration, stretching, or rotation, especially when combined with fluorescence or spectral detection. Overall, OET provides a flexible technical route from target-cell screening to functional characterization and downstream molecular analysis.
The value of OET largely comes from its ability to integrate with other single-cell technologies. When combined with electroporation and cell lysis, OET can first precisely position target single cells and then enable membrane permeabilization, gene transfection, or intracellular content release. When integrated with microfluidics, OET can perform cell capture, sorting, pairing, fusion, culture, and retrieval in a stable fluidic environment, making single-cell manipulation easier to connect with downstream assays. Integration with optoelectrowetting or electrowetting further allows simultaneous manipulation of cells and droplets, enabling single cells to be encapsulated in isolated microreaction spaces. The introduction of artificial intelligence and automated control has also improved target recognition, path planning, parallel cell transport, and system usability. Based on these integration advantages, OET has gradually moved from a laboratory micromanipulation tool toward a translational platform for biomedical research and development. Commercial systems represented by the Beacon single-cell photoconductive platform have been applied in antibody discovery, cell line development, cell therapy, and tumor immunology. In antibody development, they can rapidly screen the binding and blocking functions of antibodies secreted by individual B cells and export positive cells for sequencing. In cell line development, they support high-confidence single-cell cloning, online culture, and screening of high-producing cell lines. In cell therapy and tumor immunology, they enable single-cell-level assessment of T-cell killing, cytokine secretion, and neoantigen reactivity. Overall, the translational potential of OET lies not only in precise single-cell manipulation, but also in integrating single-cell sorting, functional testing, culture and recovery, and molecular profiling into an automated, high-throughput, and traceable research workflow.
Overall, OET provides a single-cell research platform that combines noncontact operation, low damage, programmability, and high throughput, linking single-cell screening, precise manipulation, functional analysis, culture and recovery, and downstream molecular detection. It has shown important potential in antibody discovery, cell line development, tumor immunology, and cell therapy. At the same time, several challenges still limit its broader adoption and translation. First, commercial OET systems remain expensive, and the commonly used a-Si photoconductive layer involves complex fabrication; although alternative materials such as organic photoconductors reduce preparation barriers, surface roughness, stability, and performance consistency still need improvement. Second, different cell types require different buffer conditions, voltages, frequencies, and light intensities, while standardized operating parameters are still lacking, making cross-platform reuse difficult. Third, real biological samples often require complex pretreatment, so OET systems need further integration with automated sample processing, microfluidics, downstream omics, and functional assays to form a more complete "sample input–single-cell manipulation–analysis output" workflow. In addition, because OET relies on a chip-based photoconductive layer, electrodes, and liquid environment, its current use is mainly limited to in vitro studies, while in vivo applications remain structurally and operationally difficult. "In the future, with further integration of low-cost photoconductive materials, intelligent control, label-free deep-learning recognition, automated preprocessing modules, optical tweezer arrays, and multiomics analysis, OET may evolve from a specialized single-cell manipulation device into a more accessible, automated, and comprehensive platform for precision medicine and biomanufacturing." said Weiguo Cui.
Authors of the paper include Weiguo Cui, Lu Zhang, Yuguo Dai, Yishen Zhao, Jiayao Zhang, Ao Wang, Xin Pan, Jin Yu, Lingran Kong, Tongtong Li, Lin Feng, Yu Gu, and Xue Bai.
This project was supported by the National Key R&D Program of China (2022YFF1502003).
The paper, "Optoelectronic Tweezers for Single-Cell Research: Principles, Applications, and Prospects" was published in the journal Cyborg and Bionic Systems on Jun 26, 2026, at https://doi.org/10.34133/cbsystems.0562.
