🧬 FRESH Embedded Bioprinting — 3D
A genuine WebGL/Three.js companion to the 2D FRESH support-bath simulator: a print needle traces a real freeform 3D path — with true overhangs and out-of-plane loops, not flat layers — through a jammed gelatin microparticle bath, fluidizing it locally so collagen ink can be deposited anywhere in the volume before the bath self-heals around it.
Why FRESH is a genuinely 3D printing method
The 2D original walks through FRESH's five stages — bath preparation, ink deposition, self-healing suspension, in-situ gelation and melt-away release — with a flat canvas needle tracing a heart-shaped path across a 2D plane. This companion ports the same parametric curve (x = 16 sin³t, y = 13 cos t − 5 cos 2t − 2 cos 3t − cos 4t) but lifts it into real 3D space with an added out-of-plane z-component, because that is precisely what sets FRESH apart from open-air or layer-by-layer extrusion: because the jammed gelatin bath supports the ink in every direction at once, the needle is free to thread overhangs, undercuts and closed loops that never lie in a single plane.
The bath itself is rendered as an instanced field of thousands of gelatin microparticles inside a cylindrical vat. Moving the Needle Speed slider changes how fast the tip sweeps the 3D path (mirroring the original's 2–20 mm/s range and its exact fluidization-radius formula); Bath Particle Packing rebuilds the particle field at a new density and drives the same yield-stress relation as the 2D version (yield ≈ 30 + (packing − 40) × 1.1 Pa); and Needle Gauge — a fact-only figure in the original — becomes a live control here, narrowing the local fluidization radius and the deposited ink-trail thickness as the gauge number rises. Stepping through the five stages shows particles part ahead of the needle and re-jam behind it, the ink trail gelling into a firmer, glowing tube, and finally the whole bath melting away and falling clear at 37°C to reveal the free-standing 3D construct — the same melt-away release the original describes, now visibly happening in the round.