Domain: Engineering — Biomedical Engineering
Target concept: Magnetic nanoparticle dye is guided by an external magnet to a specific region of the transparent gel.

Video generation prompt: A transparent container filled with a transparent gel in which magnetic nanoparticle dye is dispersed; a handheld magnet is slowly moved along one side of the container.

Evaluation guide:
(i) Target concept: Field-gradient-driven translational motion of superparamagnetic nanoparticles in a viscous, optically transparent medium.
Minimum mechanism: Nanoparticles must be superparamagnetic, strongly responsive to an applied magnetic field while retaining no permanent magnetization of their own (i.e., not diamagnetic, and not merely weakly/ordinarily paramagnetic). The gel must be viscous enough to suppress rapid sedimentation while still allowing field-driven migration, and the external magnet must produce a spatially varying (non-uniform) field so that a net force is exerted on the particles.
(ii)Storyline: [Frame 0–2] Container with transparent gel and uniformly dispersed dye visible; magnet stationary outside one side wall. → [Frame 3–4] Magnet begins lateral motion; dye remains uniform. → [Frame 5–7] Dye particles visibly migrate toward and adhere to inner wall adjacent to magnet; accumulation zone forms and moves synchronously. → [Frame 8–9] Magnet stops; accumulation halts immediately and remains localized without dispersion. → Perspective: Fixed frontal orthographic view showing full container height and width; side wall with magnet motion must be fully visible; background must be simple and high-contrast to confirm gel transparency and dye localization.

Manual:
Experimental Procedure
1. Place a transparent container filled with transparent gel on a stable surface.
2. Disperse magnetic nanoparticle dye uniformly throughout the gel.
3. Hold a handheld magnet against the outer surface of one side of the container.
4. Slowly move the magnet laterally along that same side.
Observation of Experimental Phenomena
Magnetic nanoparticle dye accumulates progressively along the inner wall of the container side adjacent to the moving magnet, forming a visible concentrated band that tracks the magnet’s position in real time.
Summary of Experimental Principles
Magnetic nanoparticles experience a translational force in a non-uniform magnetic field; external magnet generates field gradient that pulls particles toward region of highest field strength — i.e., the inner wall closest to the magnet.

Prompt Grounding rubric:
level_1: No transparent container is visible; no transparent gel is present inside it; no magnetic nanoparticle dye is visible in the gel; no handheld magnet is present; there is no motion of anything along the side of a container.
level_2: A transparent container is present and filled with something, but the fill is not a transparent gel (e.g., it looks like an opaque liquid, is empty, or is a solid block); the magnetic nanoparticle dye is absent or cannot be identified as a dispersed phase; a handheld magnet may be present but is not shown positioned against or interacting with the container's side.
level_3: The transparent container holds a visibly transparent gel; magnetic nanoparticle dye is visible within it as a dispersed phase (fine dark specks, streaks, or a haze); a handheld magnet is present and positioned against one side of the container; the magnet is not yet shown moving.
level_4: All elements from score 3 are present AND the handheld magnet is shown moving continuously along one side of the container in a lateral, side-to-side path, not being lifted away, rotated, or pushed through the container wall; the motion is sustained for a clearly observable stretch of the video, and the container itself stays upright and in a fixed position throughout.
level_5: All elements from score 4 are present AND the magnet's motion stays exclusively on the outer surface of one side of the container for the entire sequence: no lifting off, no crossing to an adjacent edge, and no drifting onto the top, bottom, front, or back faces; the container remains upright and stationary throughout, and the magnet's lateral path is smooth and unbroken from start to end.

Scientific and Causal Correctness rubric:
level_1: The magnetic nanoparticle dye does not respond to the magnet's presence or motion at all; it stays uniformly spread through the whole gel volume for the entire clip, with no localized concentration or alignment forming anywhere.
level_2: The dye's accumulation shows no spatial relationship to the magnet's position: it builds up on the opposite side, in the center, or in a random spot; the accumulation appears all at once rather than building up, or it persists after the magnet stops moving; the dye changes color or disappears while the magnet is moving.
level_3: The dye begins accumulating along the inner wall of the container side next to the magnet; the accumulation is localized and lines up with the magnet's position; it starts only after the magnet begins moving and stops growing once the magnet stops; the dye keeps its original color and grainy, particulate look.
level_4: All elements from score 3 are present AND the accumulation grows continuously and tracks the magnet's position: as the magnet moves, the accumulated band moves with it along the same wall; no accumulation appears on the other walls or out in the bulk gel away from the wall; the dye particles stay suspended rather than settling or clumping for reasons unrelated to the magnet.
level_5: All elements from score 4 are present AND the accumulation stays confined to the thin surface layer directly across from wherever the magnet currently sits; there is no trailing residue left behind, no soft halo spreading beyond the band, and no rebound spreading once the magnet stops; the dye's concentration fades smoothly and monotonically moving inward from the wall; no dye particles clump into visible larger aggregates or chains.

Spatiotemporal Consistency rubric:
level_1: The container suddenly changes position, size, or shape between frames; the gel surface ripples or sloshes as if it were a free liquid; the handheld magnet snaps to a new location, or briefly disappears and returns, instead of moving continuously; the lighting flickers or a shadow switches side abruptly; the camera view itself cuts, pans, or zooms without any reason tied to the demonstration.
level_2: The container stays in place but visibly warps or bulges while the magnet moves; the gel surface shows wave-like motion or swirling unrelated to any magnetic effect; the magnet's path includes non-lateral motion such as being lifted, rotated, or pressed into the container wall; the magnet's shadow detaches from it or falls in an inconsistent direction from one frame to the next.
level_3: The container stays rigid and stationary; the gel's upper surface stays flat and undisturbed; the magnet moves laterally along one side of the container at a consistent size and orientation; the container, gel, and dye all keep a stable appearance across frames with no sudden jump in any object's position.
level_4: All elements from score 3 are present AND the magnet's lateral motion is smooth and continuous, with no stutter, freeze, or dropped-frame look; the interior of the gel shows no distortion (no lensing or refraction effects that would be inconsistent with a transparent gel); the magnet's shadow falls consistently on the container and moves smoothly in step with the magnet.
level_5: All elements from score 4 are present AND the container's edges stay straight and well-defined throughout; the transparent gel keeps the background behind the container clearly visible with no added blur or color fringing; the magnet keeps a constant distance from the container surface for the whole motion; no motion blur is heavy enough to obscure the magnet's shape or the dye particles near it.