# 90 speculative candidates

Selection is a subjective editorial shortlist, not evidence of discovery. Literature screening remains exploratory.

1. **S1-0001** An eccentric rolling hinge should convert a vertical load into a repeatable lateral step.
Test: Track a weighted prototype on a level plate. Contrary: No displacement beyond drift.

2. **S1-0005** A shallow spiral channel should expel trapped bubbles toward its center during oscillatory rotation.
Test: Track bubbles with zero mean rotation. Contrary: Bubbles exhibit no net radial migration.

3. **S1-0014** A curved capillary branch should delay liquid invasion through air compression before breakthrough.
Test: Record meniscus motion in sealed and vented branches. Contrary: Breakthrough ignores trapped-air volume.

4. **S1-0023** A perforated acoustic cavity should retain a stable resonance despite partial outlet blockage if holes couple through a common plenum.
Test: Block holes sequentially and measure spectra. Contrary: Resonance shifts as much as isolated cavities.

5. **S1-0032** An asymmetric pin joint should make clearance detectable through harmonic content before large backlash occurs.
Test: Measure vibration spectra while introducing calibrated clearance. Contrary: Harmonics cannot distinguish clearance from baseline.

6. **S1-0039** A flexible optical grating on a cylindrical support should distinguish bending from uniform temperature through opposite-side diffraction shifts.
Test: Apply calibrated curvature and heating. Contrary: Both perturbations produce indistinguishable signals.

7. **S1-0046** A mechanically isolated reference cavity should cancel barometric drift in a passive differential displacement sensor.
Test: Compare output with and without reference during pressure changes. Contrary: Common-mode rejection is absent.

8. **S1-0051** A curved leaf spring should sense load position through the ratio of two resonant frequencies.
Test: Apply loads at known positions and invert the ratio. Contrary: Different positions remain spectrally indistinguishable.

9. **S1-0065** A cam-guided compression spring should deliver approximately constant output torque across a designed angular range.
Test: Measure torque against the inverse-cam model. Contrary: Torque variation exceeds the bare-spring control.

10. **S1-0081** A capillary valve containing a reentrant corner should reopen at a different pressure after gas intrusion.
Test: Measure first and subsequent opening thresholds. Contrary: Threshold has no reproducible history dependence.

11. **S1-0101** A bowed wire should rectify symmetric lateral shaking into axial crawling through contact sequencing.
Test: Film motion on level glass. Contrary: Mean travel vanishes.

12. **S1-0110** A branching capillary should route liquid according to pulse rise time rather than peak pressure alone.
Test: Apply equal-peak pressure waveforms. Contrary: Routing remains identical.

13. **S1-0119** A variable-pitch spiral spring should confine fatigue damage away from its anchor.
Test: Map strain and crack locations during cycling. Contrary: Anchor remains the dominant failure site.

14. **S1-0125** A soft pneumatic finger should retain grasp force longer when a local check chamber isolates leakage.
Test: Measure force decay after imposed puncture. Contrary: Decay is unchanged.

15. **S1-0137** A mechanically bistable gauge should preserve evidence of a pressure excursion after pressure returns to zero.
Test: Apply known pulses and inspect state. Contrary: Subthreshold and suprathreshold pulses produce indistinguishable states.

16. **S1-0145** A multilobe capillary tip should create several equal droplets per detachment cycle.
Test: Measure droplet volumes with high-speed imaging. Contrary: Volumes remain persistently unequal.

17. **S1-0155** A water-filled membrane lens should correct gravity sag when its rim tension varies azimuthally.
Test: Measure wavefront error across orientations. Contrary: Tailored tension does not reduce sag.

18. **S1-0167** A bowed bridge support should redistribute load to a secondary support before the main support yields.
Test: Measure reaction forces. Contrary: Redistribution begins only after permanent damage.

19. **S1-0182** An intermittently contacting brush seal should reduce rotational drag while preserving static sealing.
Test: Measure leakage and torque. Contrary: Drag reduction requires substantial leakage.

20. **S1-0197** A helical slit sleeve should permit extension while resisting radial dilation.
Test: Measure axial and radial compliance. Contrary: Radial dilation remains large.

21. **S1-0203** A loose collar should suppress cable galloping by intermittent impacts.
Test: Measure cable oscillation with fixed/free collar. Contrary: Amplitude remains unchanged.

22. **S1-0214** A sawtooth drainage edge should separate oil-free water from attached inert particles by different release positions.
Test: Image drops and particles. Contrary: Release positions overlap.

23. **S1-0223** A freely rotating vane should infer flow reversal timing from angular acceleration spikes.
Test: Compare against a flowmeter. Contrary: Spikes lag unpredictably.

24. **S1-0237** A corrugated wick should retain transport during bending through protected longitudinal channels.
Test: Measure flux versus curvature. Contrary: Bending blocks channels as in flat controls.

25. **S1-0246** A hollow pendulum should reveal a tiny leak through a change in its amplitude-dependent frequency.
Test: Compare sealed and calibrated-leak states. Contrary: Leak signal cannot exceed baseline drift.

26. **S1-0261** A vented lattice should survive repeated vacuum release with less permanent distortion than sealed cells.
Test: Measure shape after pressure cycles. Contrary: Venting provides no improvement.

27. **S1-0274** A patterned support bed should reduce membrane adhesion by admitting peeling air sequentially.
Test: Measure release force and front motion. Contrary: Air admission does not reduce force.

28. **S1-0286** A porous suspended plate should attenuate pressure fluctuations while passing mean liquid flow.
Test: Measure pressure transfer and mean loss. Contrary: Attenuation requires prohibitive mean loss.

29. **S1-0291** A corrugated diaphragm should generate a diagnostic overtone when a local crack first opens.
Test: Record vibration and inspect crack growth. Contrary: Overtone appears only after gross failure.

30. **S1-0297** A moving porous partition should equalize pressure between gas chambers while filtering rapid pulses.
Test: Measure static equalization and transient transfer. Contrary: Timescale separation is absent.

31. **S1-0305** A snap-through floor tile analogue should record overload location through a persistent local inversion.
Test: Apply instrumented loads. Contrary: Unloaded sites also invert.

32. **S1-0318** A bowed optical fiber guide should encode bending direction through differential path lengths.
Test: Measure paired optical delays. Contrary: Directional discrimination is absent.

33. **S1-0326** A flexible thermal bridge should make contact only after a prescribed expansion threshold.
Test: Measure conductance versus temperature. Contrary: Contact threshold is irreproducible.

34. **S1-0341** A tethered air pouch should reduce resonance of a liquid column through compliant volume exchange.
Test: Measure oscillation decay. Contrary: Exchange increases oscillation amplitude.

35. **S1-0352** A sliding friction pad should limit transmitted torque by moving to a lower-pressure region.
Test: Measure torque during overload. Contrary: Torque rises until irreversible slip damage.

36. **S1-0366** A sealed flexible sachet should mix its contents under external reciprocal compression through asymmetric folding.
Test: Image dye dispersion. Contrary: Mixing matches symmetric controls.

37. **S1-0379** A floating bell should measure gas production through discrete buoyancy-triggered releases.
Test: Deliver calibrated gas volumes. Contrary: Release volume is irreproducible.

38. **S1-0388** A capillary end-stop should reduce overshoot of a small sliding carriage.
Test: Measure stopping distance and rebound. Contrary: Fluid bridge breaks before useful damping.

39. **S1-0394** A gas-filled ring should estimate surrounding pressure through its circularity under known tether tension.
Test: Image shape against calibrated pressure. Contrary: Shape is not uniquely pressure-dependent.

40. **S1-0400** A compliant optical bench should maintain mirror alignment under uniform expansion through kinematic folding.
Test: Measure beam pointing during heating. Contrary: Pointing drift remains comparable.

41. **S1-0401** A passive optical cavity should distinguish dust deposition from mirror motion through unequal changes in linewidth and resonance frequency.
Test: Deposit calibrated inert dust. Contrary: Perturbations remain inseparable.

42. **S1-0413** A phase-shifted heating pair should identify thermal contact resistance independently of sample conductivity.
Test: Measure surface temperature fields. Contrary: Parameters remain nonidentifiable.

43. **S1-0421** An inductive ring should estimate bolt preload through reversible magnetoelastic response after temperature correction.
Test: Calibrate instrumented bolts. Contrary: Residual hysteresis prevents preload inference.

44. **S1-0434** A floating torsional disk should measure interfacial viscosity independently of bulk viscosity using frequency variation.
Test: Test known interfaces. Contrary: Bulk contribution cannot be separated.

45. **S1-0447** A passive liquid lens should measure acceleration magnitude from focal astigmatism.
Test: Apply known acceleration directions. Contrary: Astigmatism is dominated by contact-line hysteresis.

46. **S1-0459** A spatially chirped grating should locate a crack through the wavelength range losing diffraction coherence.
Test: Introduce known cracks. Contrary: Coherence loss is nonlocal and ambiguous.

47. **S1-0467** A differential acoustic echo should reveal slow creep at a joint through changing reflection phase.
Test: Measure loaded joints over time. Contrary: Phase drift is dominated by temperature.

48. **S1-0479** A paired liquid-column sensor should estimate pressure while compensating evaporation loss.
Test: Measure long-term calibration against reference. Contrary: Evaporation compensation fails.

49. **S1-0487** A passive torsion indicator should measure screw loosening from angular resonance without referencing screw-head position.
Test: Loosen known increments. Contrary: Resonance does not track preload loss.

50. **S1-0498** A thermal pulse pair should identify heat capacity separately from thermal resistance at a small joint.
Test: Fit standards with known parameters. Contrary: Fits remain nonidentifiable.

51. **S1-0501** A hanging thermal flap should oscillate under steady heating through delayed self-shading.
Test: Measure motion under constant illumination. Contrary: Only transient motion occurs.

52. **S1-0512** A capillary thermal diode should reverse its preferred direction after mechanical inversion of its reservoir.
Test: Measure bidirectional conductance. Contrary: Directionality does not reverse.

53. **S1-0523** A liquid thermal reservoir should level itself as its contents expand, preserving a fixed optical path.
Test: Measure path length during heating. Contrary: Path changes as in rigid cells.

54. **S1-0537** A capillary-fed membrane should cool uniformly despite partial inlet obstruction.
Test: Map temperature under controlled blockage. Contrary: Hotspots track blocked regions.

55. **S1-0545** A layered thermal shield should reduce temperature cycling through a delayed ventilation path.
Test: Measure cycle amplitude and mean temperature. Contrary: Amplitude reduction causes unacceptable mean heating.

56. **S1-0557** A thermal bridge with a sliding overlap should maintain conductance during structural expansion.
Test: Measure conductance versus extension. Contrary: Overlap contact resistance dominates drift.

57. **S1-0568** A capillary vent should prevent pressure buildup during thermal cycling without continuous liquid loss.
Test: Measure pressure and mass. Contrary: Pressure control requires substantial liquid leakage.

58. **S1-0577** A passive heater shunt should route power thermally toward a cold region through contact closure.
Test: Map temperature fields. Contrary: Closure routes heat to the hotter region.

59. **S1-0589** A liquid-cooled hinge should change damping less with temperature when its expansion volume is vented.
Test: Measure damping-temperature curves. Contrary: Venting gives no compensation.

60. **S1-0595** A compliant radiator mount should reduce thermal fatigue by permitting reversible lateral slip.
Test: Measure strain and fatigue life. Contrary: Slip adds no lifetime benefit.

61. **S1-0603** A loosely packed bead column should preserve impact direction through asymmetric force-chain scars.
Test: Inspect post-impact contact marks. Contrary: Scars cannot distinguish direction.

62. **S1-0614** A spiral acoustic path should compress pulse duration through controlled frequency-dependent delay.
Test: Measure input/output pulses. Contrary: Pulse broadens instead.

63. **S1-0627** A grain-filled compliant tube should stiffen under bending through local jamming.
Test: Measure stiffness versus curvature. Contrary: Stiffness remains constant or decreases.

64. **S1-0638** A cavity array should identify which cell is wet from the disappearance of one localized mode.
Test: Wet known cells. Contrary: Modes shift globally without localization.

65. **S1-0646** A curved waveguide should separate closely spaced acoustic modes through polarization-selective bends.
Test: Measure modal transmission. Contrary: Modes remain inseparable.

66. **S1-0657** A grain-filled bellows should maintain damping under orientation changes through compartmentalization.
Test: Measure damping over rotations. Contrary: Orientation sensitivity remains equal.

67. **S1-0669** A narrow grain channel should suppress size segregation when its walls alternately diverge and converge.
Test: Measure mixture uniformity. Contrary: Geometry increases segregation.

68. **S1-0678** A layered acoustic reflector should expose trapped air by a delayed echo that survives thickness variation.
Test: Test known gaps. Contrary: Thickness echoes mask air-gap response.

69. **S1-0686** A compliant acoustic neck should resist dust clogging through sound-driven wall motion.
Test: Dose inert dust. Contrary: Motion does not prevent blockage.

70. **S1-0697** A granular tray should suppress avalanches by dividing its free surface with flexible ribs.
Test: Measure avalanche sizes. Contrary: Ribs create larger correlated avalanches.

71. **S1-0701** A folded lattice should develop negative incremental Poisson response only after its hinges contact.
Test: Measure transverse strain. Contrary: Contact produces no sign change.

72. **S1-0714** A soft suction foot should detach with lower energy when a tendon opens an edge vent.
Test: Measure detachment work. Contrary: Venting offers no reduction.

73. **S1-0728** A flexural differential should average two input motions while rejecting equal-and-opposite disturbance forces.
Test: Apply independent inputs and forces. Contrary: Output remains force-sensitive.

74. **S1-0739** A kinematic flexure should tolerate one damaged hinge through redundant load paths.
Test: Cut one hinge and measure motion. Contrary: Mechanism loses useful motion.

75. **S1-0746** A compliant stepping mechanism should count pressure cycles without electronic power.
Test: Cycle known pressures. Contrary: Skipped or double steps dominate.

76. **S1-0758** A compliant object holder should self-tighten under vibration without ratcheting permanently.
Test: Measure grip and release force. Contrary: Tightening causes irreversible lockup.

77. **S1-0768** A flexure-mounted payload should remain level during slow support rotation through gravity-biased geometry.
Test: Measure payload angle. Contrary: Support rotation passes through.

78. **S1-0778** A flexible wheel should climb a step by forming a temporary flat contact patch.
Test: Measure climb threshold. Contrary: Patch formation reduces climbing ability.

79. **S1-0786** A soft actuator should reveal internal delamination through a changed pressure-volume loop before gross rupture.
Test: Introduce controlled debonds. Contrary: Loop changes are undetectable.

80. **S1-0798** A flexible joint cover should prevent pinch gaps without materially increasing actuation torque.
Test: Measure gap and torque. Contrary: Protection requires large torque increase.

81. **S1-0802** A dead-end microgroove should capture suspended particles by repeated flow reversal without net filtration flow.
Test: Count retained inert tracers. Contrary: Capture equals stagnant controls.

82. **S1-0813** A slow rotating stirrer should mix more efficiently when its blade changes pitch passively on reversal.
Test: Measure mixing energy. Contrary: Pitch changes add no benefit.

83. **S1-0827** A floating wick should collect thin surface films faster when its buoyancy decreases after wetting.
Test: Track film uptake. Contrary: Sinking interrupts collection.

84. **S1-0838** A soft pipe elbow should distribute pressure impulse over time through controlled unbending.
Test: Measure pressure and shape. Contrary: Unbending produces a larger secondary spike.

85. **S1-0849** A submerged porous cone should reduce bubble plume wandering by distributed gas release.
Test: Image plume centroid. Contrary: Wandering is unchanged.

86. **S1-0861** A capillary fork should infer viscosity from transient branch-filling asymmetry after a fixed pressure pulse.
Test: Test calibration fluids. Contrary: Wetting variation overwhelms viscosity response.

87. **S1-0872** A capillary stop network should encode a pressure history as a sequence of filled chambers.
Test: Apply known pulse sequences. Contrary: Different histories produce identical filling.

88. **S1-0883** A compliant microchannel should detect particle passage through a resolvable wall-displacement pulse.
Test: Track particles and displacement. Contrary: Pulses remain below noise.

89. **S1-0894** A liquid-filled beam should redistribute internal mass during bending and increase its recovery torque.
Test: Measure torque and liquid position. Contrary: Redistribution reduces recovery.

90. **S1-0900** A passive flow-memory device should reset after complete drying and reproduce its original switching sequence.
Test: Cycle filling and drying. Contrary: Residual deposits prevent reproducible reset.