Principle 31. Porous materials
A. Make an object porous or add porous elements (inserts, coatings, etc.).
o Drill holes in a structure to reduce the weight.
B. If an object is already porous, use the pores to introduce a useful substance or function.
o Use a porous metal mesh to wick excess solder away from a joint.
o Store hydrogen in the pores of a palladium sponge. (Fuel “tank” for the hydrogen car–much safer than storing hydrogen gas)
Principle 32. Color changes
A. Change the color of an object or its external environment.
o Use safe lights in a photographic darkroom.
B. Change the transparency of an object or its external environment.
o Use photolithography to change transparent material to a solid mask for semiconductor processing. Similarly, change mask material from transparent to opaque for silk screen processing.
Principle 33. Homogeneity
A. Make objects interacting with a given object of the same material (or material with identical properties).
o Make the container out of the same material as the contents, to reduce chemical reactions.
o Make a diamond cutting tool out of diamonds.
Principle 34. Discarding and recovering
A. Make portions of an object that have fulfilled their functions go away (discard by dissolving, evaporating, etc.) or modify these directly during operation.
o Use a dissolving capsule for medicine.
o Sprinkle water on cornstarch-based packaging and watch it reduce its volume by more than 1000X!
o Ice structures: use water ice or carbon dioxide (dry ice) to make a template for a rammed earth structure, such as a temporary dam. Fill with earth, then, let the ice melt or sublime to leave the final structure.
B. Conversely, restore consumable parts of an object directly in operation.
o Self-sharpening lawn mower blades
o Automobile engines that give themselves a “tune up” while running (the ones that say “100,000 miles between tune ups”)
Principle 35. Parameter changes
A. A. Change an object’s physical state (e.g. to a gas, liquid, or solid.
o Freeze the liquid centers of filled candies, then dip in melted chocolate, instead of handling the messy, gooey, hot liquid.
o Transport oxygen or nitrogen or petroleum gas as a liquid, instead of a gas, to reduce volume.
B. Change the concentration or consistency.
o Liquid hand soap is concentrated and more viscous than bar soap at the point of use, making it easier to dispense in the correct amount and more sanitary when shared by several people.
C. Change the degree of flexibility.
o Use adjustable dampers to reduce the noise of parts falling into a container by restricting the motion of the walls of the container.
o Vulcanize rubber to change its flexibility and durability.
D. Change the temperature.
o Raise the temperature above the Curie point to change a ferromagnetic substance to a paramagnetic substance.
o Raise the temperature of food to cook it. (Changes taste, aroma, texture, chemical properties, etc.)
o Lower the temperature of medical specimens to preserve them for later analysis.
Principle 36. Phase transitions
A. Use phenomena occurring during phase transitions (e.g. volume changes, loss or absorption of heat, etc.).
o Water expands when frozen, unlike most other liquids. Hannibal is reputed to have used this when marching on Rome a few thousand years ago. Large rocks blocked passages in the Alps. He poured water on them at night. The overnight cold froze the water, and the expansion split the rocks into small pieces which could be pushed aside.
o Heat pumps use the heat of vaporization and heat of condensation of a closed thermodynamic cycle to do useful work.
Principle 37. Thermal expansion
A. Use thermal expansion (or contraction) of materials.
o Fit a tight joint together by cooling the inner part to contract, heating the outer part to expand, putting the joint together, and returning to equilibrium.
B. If thermal expansion is being used, use multiple materials with different coefficients of thermal expansion.
o The basic leaf spring thermostat: (2 metals with different coefficients of expansion are linked so that it bends one way when warmer than nominal and the opposite way when cooler.)
Principle 38. Strong oxidants
A. Replace common air with oxygen-enriched air.
o Scuba diving with Nitrox or other non-air mixtures for extended endurance
B. Replace enriched air with pure oxygen.
o Cut at a higher temperature using an oxy-acetylene torch.
o Treat wounds in a high pressure oxygen environment to kill anaerobic bacteria and aid healing.
C. Expose air or oxygen to ionizing radiation.
D. Use ionized oxygen.
o Ionize air to trap pollutants in an air cleaner.
E. Replace ozonized (or ionized) oxygen with ozone.
o Speed up chemical reactions by ionizing the gas before use.
Principle 39. Inert atmosphere
A. Replace a normal environment with an inert one.
o Prevent degradation of a hot metal filament by using an argon atmosphere.
B. Add neutral parts, or inert additives to an object.
o Increase the volume of powdered detergent by adding inert ingredients. This makes it easier to measure with conventional tools.
Principle 40. Composite materials
A. Change from uniform to composite (multiple) materials.
o Composite epoxy resin/carbon fiber golf club shafts are lighter, stronger, and more flexible than metal. Same for airplane parts.
o Fiberglass surfboards are lighter and more controllable and easier to form into a variety of shapes than wooden ones.
