image: (A) C-Sight, IMM mechanism. (B) C-Tac, MDM mechanism. (C) C-SighTac, IMM + MDM mechanism. (D) Vi-C-Tac, MDM + MFM mechanism. (E) Vi-C-Sight, IMM + MFM mechanism. The diagram for each design illustrates its unique internal structure and material assignment.
Credit: Wen Fan, Imperial College London.
A research paper by scientists at Imperial College London presented CrystalTac, a vision-based tactile sensor family fabricated via rapid monolithic manufacturing.
The research paper, published on Apr. 10, 2025 in the journal Cyborg and Bionic Systems.
Recently, vision-based tactile sensors (VBTSs) have gained popularity in robotics systems. The sensing mechanisms of most VBTSs can be categorized based on the type of tactile features they capture. Each category requires specific structural designs to convert physical contact into optical information. The complex architectures of VBTSs pose challenges for traditional manufacturing techniques in terms of design flexibility, cost-effectiveness, and quality stability. Previous research has shown that monolithic manufacturing using multimaterial 3-dimensional printing technology can address these challenges but fails to bridge the gap between the design phase and creation phase of VBTSs. “Thereby, we develop the CrystalTac family, a series of VBTSs designed with on-demand sensing mechanisms and fabricated through rapid monolithic manufacturing.” said the author Wen Fan, a researcher at Imperial College London, “The CrystalTac family aims to highlight the potential of rapid monolithic manufacturing techniques in VBTS development and inspire further research in tactile sensing and manipulation.”
The research process of this study is divided into the following steps: Firstly, the study summarized the design and creation methods of known VBTSs and proposed a new categorization method to encapsulate their typical sensing mechanisms. Subsequently, the study investigated the manufacturing feasibility of VBTSs based on different sensing mechanisms produced through the monolithic manufacturing method in terms of technological and practical feasibility, bridging the gap between design and creation of VBTSs. Building on these insights, the study developed the CrystalTac family, a series of sensors that includes C-Tac, C-Sight, C-SighTac, Vi-C-Tac, and Vi-C-Sight, each design based on a unique tactile sensing mechanism, aiming to demonstrate design-led flexible creation through rapid monolithic manufacturing. Finally, a series of functional experiments evaluated the CrystalTac series in terms of sensing performance, cost-effectiveness and design flexibility, while optimized sub-component manufacturing techniques and several novel marker designs were introduced to enhance future scalability and application potential. The experimental results show that the CrystalTac series has good performance and meets its design goals through a unique tactile sensing mechanism.
The CrystalTac family can be regarded as an initial template, with no strict parameter limitations for each sensor detail, thereby encouraging the community to view it as a foundation for further development. The contribution of this work lies in demonstrating the capability of rapid monolithic manufacturing to produce VBTSs with various tactile sensing mechanisms, providing confidence and inspiration to other researchers in the tactile robotics field. “In future work, we aim to advance the new CrystalTac series by enhancing the capabilities of monolithic manufacturing in terms of production quality and efficiency, as well as multimaterial printing for VBTSs. These technologies can be seamlessly integrated with tactile sensory enhancements in dexterous hands to perform tasks such as human–computer interaction or dexterous manipulation.” said Wen Fan.
Authors of the paper include Wen Fan, Haoran Li, and Dandan Zhang.
Wen Fan and Haoran Li are partially funded by CSC scholarship. The authors would like to acknowledge the Royal Society Research Grant (RGS/R1/221122).
The paper, “CrystalTac: Vision-Based Tactile Sensor Family Fabricated via Rapid Monolithic Manufacturing” was published in the journal Cyborg and Bionic Systems on Apr. 10, 2025, at DOI: 10.34133/cbsystems.0231.