Additive manufacturing is enabling soft robots with increasingly complex geometries, creating a demand for sensing solutions that remain compatible with single-material, one-step fabrication. Optical soft sensors are attractive for monolithic printing, but their performance is often degraded by uncontrolled light propagation (ambient coupling, leakage, scattering), while common miti- gation strategies typically require multimaterial interfaces. Here, we present an approach for 3D printed soft optical sensing (SOLen), in which a printed lens is placed in front of an emitter within a Y-shaped waveguide. The sensing mechanism relies on deformation-induced lens rotation and focal-spot translation, redistributing optical power between the two branches to generate a differential output that encodes both motion direction and amplitude. An acrylate polyurethane resin was modified with lauryl acrylate to improve compliance and optical transmittance, and single-layer optical characterization was used to derive wavelength-dependent refractive index and transmittance while minimizing DLP layer-related artifacts. The measured refractive index was used in simulations to design a lens profile for a target focal distance, which was then printed with sub-millimeter fidelity. Rotational tests demonstrated reproducible branch-selective signal switching over multiple cycles. These results establish a transferable material-to-optics workflow for soft optical sensors with lens with new functionalities for next-generation soft robots

翻译：增材制造正推动软体机器人几何结构日益复杂化，从而催生了与单材料一步式制造工艺兼容的传感解决方案需求。光学软体传感器因其适用于整体打印而备受关注，但其性能常受非受控光传播（环境耦合、泄漏、散射）的影响，而常见的缓解策略通常需要多材料界面。本文提出一种3D打印软体光学传感（SOLen）方法，通过在Y形波导内的发射器前方置入打印透镜实现传感。该传感机制依赖于形变诱导的透镜旋转与焦点位移，使光功率在两个分支间重新分布，从而产生编码运动方向与幅值的差分输出。通过添加丙烯酸月桂酯对丙烯酸聚氨酯树脂进行改性，以提升柔顺性与光学透射率；采用单层光学表征方法推导波长相关的折射率与透射率，同时最小化数字光处理分层效应。将实测折射率应用于仿真设计，获得了目标焦距的透镜轮廓，并以亚毫米级精度完成打印。旋转测试表明该系统能在多次循环中实现可重复的分支选择性信号切换。这些研究成果为带透镜软体光学传感器建立了可迁移的材料-光学协同工作流程，为下一代软体机器人赋予了新功能。