{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T06:35:34Z","timestamp":1772692534611,"version":"3.50.1"},"reference-count":15,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T00:00:00Z","timestamp":1772236800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Current multi-axis force sensors often rely on complex mechanical structures or arrays of discrete transducers, resulting in larger footprints, higher complexity, and limited scalability for compact applications such as robotic fingertips or wearable tactile interfaces. To address these limitations, this paper introduces a novel optical sensing approach that uses a top-layer patterned color surface and an array of color sensors to decouple and measure normal, shear, and torsional forces within a highly compact 15 \u00d7 15 mm footprint. The patterned surface functions as a visual encoding layer, where applied forces induce measurable, direction-dependent shifts in reflected color distribution. By deploying multiple color sensors in an array, each sensor captures localized color variations, enabling spatial reconstruction of both magnitude and direction of applied loads through differential color analysis. The sensor\u2019s performance was validated through robotic gripper integration, where it successfully provided multi-axis force feedback and enabled adaptive gripping force adjustment to achieve robust and stable object manipulation. The experimental results confirm the system\u2019s ability to effectively sensing 3D forces and torsion forces, and support closed-loop control in adaptive robotic grasping. This design presents a scalable, low-profile alternative to conventional multi-axis force sensors, suitable for integration into space-constrained robotic and haptic systems.<\/jats:p>","DOI":"10.3390\/s26051534","type":"journal-article","created":{"date-parts":[[2026,3,2]],"date-time":"2026-03-02T08:51:57Z","timestamp":1772441517000},"page":"1534","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A 3D-Force and Torsion Sensor Using Patterned Color Encoding"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-9829-9523","authenticated-orcid":false,"given":"Tak Nok Douglas","family":"Yu","sequence":"first","affiliation":[{"name":"Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5123-315X","authenticated-orcid":false,"given":"Hao","family":"Ren","sequence":"additional","affiliation":[{"name":"Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong, China"},{"name":"Shenzhen Research Institute, The Hong Kong University of Science and Technology, Shenzhen 518057, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5799-7524","authenticated-orcid":false,"given":"Yajing","family":"Shen","sequence":"additional","affiliation":[{"name":"Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong, China"},{"name":"Shenzhen Research Institute, The Hong Kong University of Science and Technology, Shenzhen 518057, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Gandarias, J.M., G\u00f3mez-de Gabriel, J.M., and Garc\u00eda-Cerezo, A. (2018). Enhancing Perception with Tactile Object Recognition in Adaptive Grippers for Human\u2013Robot Interaction. Sensors, 18.","DOI":"10.3390\/s18030692"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"167189","DOI":"10.1016\/j.cej.2025.167189","article-title":"A stretchable tactile sensor with deep learning-enabled 3D force decoding for human and robotic interfaces","volume":"521","author":"Min","year":"2025","journal-title":"Chem. Eng. J."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Chen, J., Xia, M., Chen, P., Cai, B., Chen, H., Xie, X., Wu, J., and Shi, Q. (2025). Innovations in Multidimensional Force Sensors for Accurate Tactile Perception and Embodied Intelligence. AI Sens., 1.","DOI":"10.3390\/aisens1020007"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Leslie, O., Bulens, D.C., and Redmond, S.J. (2023). Design, Fabrication, and Characterization of a Novel Optical Six-Axis Distributed Force and Displacement Tactile Sensor for Dexterous Robotic Manipulation. Sensors, 23.","DOI":"10.3390\/s23249640"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"eadi2445","DOI":"10.1126\/sciadv.adi2445","article-title":"An optical-based multipoint 3-axis pressure sensor with a flexible thin-film form","volume":"9","author":"Wang","year":"2023","journal-title":"Sci. Adv."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Rehan, M., Saleem, M.M., Tiwana, M.I., Shakoor, R.I., and Cheung, R. (2022). A Soft Multi-Axis High Force Range Magnetic Tactile Sensor for Force Feedback in Robotic Surgical Systems. Sensors, 22.","DOI":"10.3390\/s22093500"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1016\/j.eng.2025.02.008","article-title":"A Soft Tactile Unit with Three-Dimensional Force and Temperature Mathematical Decoupling Ability for Robots","volume":"55","author":"Yang","year":"2025","journal-title":"Engineering"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3135","DOI":"10.1038\/s41467-025-58403-3","article-title":"A robust and omnidirectional-sensitive electronic antenna for tactile-induced perception","volume":"16","author":"Ren","year":"2025","journal-title":"Nat. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"eabc8801","DOI":"10.1126\/scirobotics.abc8801","article-title":"Soft magnetic skin for super-resolution tactile sensing with force self-decoupling","volume":"6","author":"Yan","year":"2021","journal-title":"Sci. Robot."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1038\/s41528-024-00325-z","article-title":"Large-area magnetic skin for multi-point and multi-scale tactile sensing with super-resolution","volume":"8","author":"Hu","year":"2024","journal-title":"NPJ Flex. Electron."},{"key":"ref_11","unstructured":"(2025, December 17). SuperMag: Vision-Based Tactile Data Guided High-Resolution Tactile Shape Reconstruction for Magnetic Tactile Sensors. Available online: https:\/\/arxiv.org\/html\/2507.20002v1."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"eady2869","DOI":"10.1126\/scirobotics.ady2869","article-title":"Visual-tactile pretraining and online multitask learning for humanlike manipulation dexterity","volume":"11","author":"Ye","year":"2026","journal-title":"Sci. Robot."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Yuan, W., Dong, S., and Adelson, E.H. (2017). GelSight: High-Resolution Robot Tactile Sensors for Estimating Geometry and Force. Sensors, 17.","DOI":"10.3390\/s17122762"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"eabm7187","DOI":"10.1126\/scirobotics.abm7187","article-title":"A biomimetic elastomeric robot skin using electrical impedance and acoustic tomography for tactile sensing","volume":"7","author":"Park","year":"2022","journal-title":"Sci. Robot."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"eaea1867","DOI":"10.1126\/sciadv.aea1867","article-title":"Stretchable complementary integrated electronics based on elastic dual-type transistors","volume":"11","author":"Zhang","year":"2025","journal-title":"Sci. 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