Show HN: I made a new sensor out of 3D printer filament for my PhD

Overall reception

• Thread is overwhelmingly positive; many call the sensor clever, beautiful, and “what hacking is all about.”
• People appreciate that it uses cheap, accessible materials instead of specialized lab-only processes.
• Several praise the write-up as unusually readable for PhD work.

Clarity and communication

• Early readers say the article initially buried the answer to “what does it do?” (bend localization).
• After the post was updated with a simple “bent rope / squishy cable that knows where it’s bent” explanation, readers report it’s much clearer and more trustworthy.
• Suggestions include: give concrete use cases early, add a short video of the core effect, and avoid rainbow/jet colormaps for accessibility.

Potential applications

• Soft robotics dominates: flapping wings, swimming fins, compliant arms, soft robot “legs” and skins.
• Other ideas: data gloves, robotic proprioception, surgical and medical shape sensing, industrial monitoring, tactile skins using 2D/3D layouts, and golf swing tracking (though practicality there is debated).
• Some imagine long runs along robot arms, with learned mapping from sensor data to end-effector pose.

Relation to existing technologies

• Multiple commenters compare it to time-domain reflectometry / OTDR, distributed acoustic/temperature sensing, fiber Bragg gratings, and early data gloves / Power Glove.
• Consensus: conceptually similar in “shape sensing,” but this design trades high-speed timing and expensive optics for simple, coded air gaps and multiple fibers, optimized for soft, low-cost systems.
• Cost and complexity of FBG-based systems are highlighted as motivation for this simpler approach.

Technical questions and ideas

• Questions about multiple bends and directionality: some worry attenuation will just add; others note that relative attenuation patterns across fibers and Bayesian modeling could disambiguate, up to saturation.
• Ideas: denser gaps to reduce dead zones, multi-lobe (e.g., 3-way) layouts for bend direction, different refractive media in gaps, space-filling curves for 2D/3D tactile sensing.
• Fabrication discussion covers using TPU vs PMMA, why total air gaps outperform scratches or partial cladding removal, and limitations of 3D printing due to optical losses.
• Kalman filtering is currently simple 1D smoothing, mainly chosen for familiarity and potential future sensor fusion.

IP and PhD context

• Commenters encourage commercialization and IP protection; the university is reportedly pursuing this.
• Side discussion analyzes how a 3-year PhD was possible, the role of prior master’s degrees, and structural differences between course-heavy and publication-heavy PhD programs.