Paper

{
  "raw_xml": "<entry>\n    <id>http://arxiv.org/abs/2602.17421v1</id>\n    <title>3D-printed Soft Optical sensor with a Lens (SOLen) for light guidance in mechanosensing</title>\n    <updated>2026-02-19T14:54:00Z</updated>\n    <link href='https://arxiv.org/abs/2602.17421v1' rel='alternate' type='text/html'/>\n    <link href='https://arxiv.org/pdf/2602.17421v1' rel='related' title='pdf' type='application/pdf'/>\n    <summary>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</summary>\n    <category scheme='http://arxiv.org/schemas/atom' term='cs.RO'/>\n    <published>2026-02-19T14:54:00Z</published>\n    <arxiv:comment>11 pages, 5 figures, submitted to Materials &amp; Design</arxiv:comment>\n    <arxiv:primary_category term='cs.RO'/>\n    <author>\n      <name>Diana Cafiso</name>\n    </author>\n    <author>\n      <name>Petr Trunin</name>\n    </author>\n    <author>\n      <name>Carolina Gay</name>\n    </author>\n    <author>\n      <name>Lucia Beccai</name>\n    </author>\n  </entry>"
}