40 Inventive Principles for resolving
technical contradictions

Genrich Altshuller discovered forty patterns of inventive solutions, known as 40
Inventive Principles. (TRIZ – Theory of Inventive Problem Solving).
The analysis of several thousand patents led to the conclusion that inventive tasks and
technical contradictions could be solved by a limited number of basic principles.
These principles were produced after analyzing over 40,000 inventions. They can resolve many technical contradictions without compromise and are useful TRIZ creativity tools in a variety of problem-solving.
Already in 1956, 5 Principles were proposed, 18 Principles were developed in 1959, and in 1964 a system including 31 methods was proposed.
Only in 1971 was the development of a complete system including 40 Principles, which were presented in a small work:
Altshuller G.S. The main principle of eliminating technical contradictions in solving inventive problems. – Baku: Ganjlik, 1971. – 52 p.
After that, the system of 40 techniques was improved, and its options were published in the book:
Altshuller G.S. Algorithm of Invention. – Moscow: Moscowskiy Rabochy, 1973.
Altshuller G.S. Creativity as an exact science. Theory of solving inventive problems. – Moscow: Sovietskoe radio, 1979.
Search for new ideas: technology and inventive solutions / G.S. Altshuller, B.L. Zlotin, A.V. Zusman, V.I. Filatov. – Chisinau: Cartya Moldovenienasca, 1989.
Althsuller G.S., Zlotin B.L., Zusman A.V., Filatov V.I. Search for new ideas: from insight to technology (Theory and practise of inventive problem solving), Kishinev: Kartya Moldovenyaska Publishing House, 1989.
There are a number of modifications to Inventive Principles. V. Petrov performed a comparative analysis of these principles in his book:
V. Petrov History of invention principles development. Information materials. Tel Aviv, 2006 – 73 p.
Many of the principles have two, three sub-principles. Multiple examples of application for each principle are also accumulated for illustration.

Different formats for the 40 Inventive Principles were developed:
1. 40 Inventive Principles by G.S. Altshuller
2. 40 Inventive Principles by Oxford Creativity
3. 40 Inventive Principles by Karen Tate and Ellen Domb

40 Inventive Principles

In: Genrich Altshuller. The Innovation Algorithm: TRIZ, Systematic Innovation
and Technical Creativity. Worcester, Mass. : Technical Innovation Center, Inc., 1999.

1. Segmentation

a. Divide an object into independent parts.
b. Make an object sectional (for easy assembly or disassembly).
c. Increase the degree of an object’s segmentation.
Example: A tire that consists of 12 independent sections

2. Extraction

(Extracting, Retrieving, Removing)
a. Extract the “disturbing” part or property from an object.
b. Extract only the necessary part or property from an object.
Example: The collision of birds and aeroplanes can result in aeroplane crashes and consequent casualties. There are many U.S. patents for methods to scare birds away from airport areas —mechanical scarecrows, chemical diffusion, etc. The best was the loud playing of tape recordings of frightened birds. Here, the bird’s voices were separated from the birds. This solution is quite unusual, but perfectly supports the principle of Extraction.

3. Local Quality

a. Transition from homogeneous to heterogeneous structure of an object or outside environment (action).
b. Different parts of an object should carry out different functions.
c. Each part of an object should be placed under conditions that are most
favourable for its operation.

4. Asymmetry

a. Replace symmetrical form(s) with asymmetrical form(s).
b. If an object is already asymmetrical, increase its degree of asymmetry.
Example: The outer section of an asymmetrical tire is made from stronger material to withstand impact when colliding with curbs.

5. Consolidation

a. Consolidate in space homogeneous objects or objects destined for contiguous operations.
b. Consolidate in time homogeneous or contiguous operations.
Example: An underwater rescue device for bringing people who are trapped in an air bubble of a sunken ship to the surface with the help of helmets. This device is different because it has two-or-three helmets, with hoses and fittings for connecting to valves mounted on the diving suits allowing for the regulation of air supplied to helmets. This invention improves the efficiency of rescue work.

6. Universality

a. An object can perform several different functions; therefore, other elements can be removed.
Example: In Japan, the possibility of building an oil tanker that contained a refinery was considered. The idea for the project was to refine crude oil during transportation to its destination.

7. Nesting (Matrioshka)

a. One object is placed inside another.
That object is placed inside a third one. And so on . . .
b. An object passes through a cavity in another object.

8. Counterweight

a. Compensate for the weight of an object by combining it with another object that provides a lifting force.
b. Compensate for the weight of an object with aerodynamic or hydrodynamic forces influenced by the outside environment.

9. Prior Counteraction

a. Preload counter tension to an object to compensate for excessive and
undesirable stress.

10. Prior Action

a. Perform required changes to an object completely or partially in advance.
b. Place objects in advance so that they can go into action immediately from
the most convenient location.
Example: A method for removing a plaster cast by using a wire handsaw. This method is different because it consists of a blade inserted into a plastic tube that is then placed inside the plaster cast while the cast is being applied.
Because of this, the cast is cut from the inside out, without harming the patient’s skin. This method prevents trauma and makes removal of the cast easy.

11. Cushion in Advance

a. Compensate for the relatively low reliability of an object with emergency
measures prepared in advance.
A method to prevent forest fires from spreading is by planting barrier strips made of plants.
This method is different because it introduces chemicals, or biologically assimilated fertilizers that slow combustion, into the soil. This promotes the development of fire resistance properties in plants.

12. Equipotentiality

a. Change the condition of the work in such a way that it will not require
lifting or lowering an object.

13. Do It in Reverse

a. Instead of the direct action dictated by a problem, implement an opposite
action (i.e., cooling instead of heating).
b. Make the movable part of an object, or outside environment, stationary —
and stationary part moveable.
c. Turn an object upside-down.

14. Spheroidality

a. Replace linear parts with curved parts, flat surfaces with spherical surfaces, and cube shapes with ball shapes.
b. Use rollers, balls, spirals.
c. Replace linear motion with rotational motion; utilize centrifugal force.

15. Dynamicity

a. Characteristics of an object or outside environment, must be altered to provide optimal performance at each stage of an operation.
b. If an object is immobile, make it mobile. Make it interchangeable.
c. Divide an object into elements capable of changing their position
relative to each other.

16. Partial or Excessive Action

a. If it is difficult to obtain 100% of the desired effect, achieve more or less of the desired effect.

17. Transition Into a New Dimension

a. Transition one-dimensional movement, or placement, of objects into twodimensional; two-dimensional to threedimensional, etc.
b. Utilize multi-level composition of objects.
c. Incline an object, or place it on its side.
d. Utilize the opposite side of a given surface.
e. Project optical lines onto neighbouring areas, or onto the reverse side, of an
object.

18. Mechanical Vibration

a. Utilize oscillation.
b. If oscillation exists, increase its frequency to ultrasonic.
c. Use the frequency of resonance.
d. Replace mechanical vibrations with piezo-vibrations.
e. Use ultrasonic vibrations in conjunction with an electromagnetic field.

19. Periodic Action

a. Replace a continuous action with a periodic one (impulse).
b.If the action is already periodic, change its frequency.
c. Use pauses between impulses to provide additional action.

20. Continuity of Useful Action

a. Carry out an action without a break. All parts of the object should constantly operate at full capacity.
b. Remove idle and intermediate motion.
c. Replace “back-and-forth” motion with a rotating one.

21. Rushing Through

a. Perform harmful and hazardous operations at a very high speed.
Example: During the unloading of a log carrier, it is tilted by a special ship. To unload all cargo into the water, the carrier must be tilted at an angle that is too high and unsafe. This new method offers a smaller tilting angle through the use of a jerking action. An impulse is developed that allows the logs to unload at a reduced angle.

22. Convert Harm Into Benefit

a. Utilize harmful factors — especially environmental — to obtain a positive effect.
b. Remove one harmful factor by combining it with another harmful factor.
c. Increase the degree of harmful action to such an extent that it ceases to be harmful.

23. Feedback

a. Introduce feedback.
b. If feedback already exists, change it.

24. Mediator

a. Use an intermediary object to transfer or carry out an action.
b. Temporarily connect the original object to one that is easily removed.

25. Self-service

a. An object must service itself and carry out supplementary and repair operations.
b. Make use of waste material and energy.

26. Copying

a. A simplified and inexpensive copy should be used in place of a fragile original or an object that is inconvenient to operate.
b. If a visible optical copy is used, replace it with an infrared or ultraviolet copy.
c. Replace an object (or system of objects) with their optical image. The image can
then be reduced or enlarged.

27. Dispose

a. Replace an expensive object with a cheap one, compromising other properties (i.e.,
longevity).

28. Replacement of Mechanical System

a. Replace a mechanical system with an optical, acoustical, thermal or olfactory system.
b. Use an electric, magnetic or electromagnetic field to interact with an object.
c. Replace fields that are:
1. Stationary with mobile.
2. Fixed with changing in time.
3. Random with structured.
d. Use fields in conjunction with ferromagnetic particles.

29. Pneumatic or Hydraulic Constructions

a. Replace solid parts of an object with a gas or liquid. These parts can now
use air or water for inflation, or use pneumatic or hydrostatic cushions.

30. Flexible Membranes or Thin Films

a. Replace customary constructions with flexible membranes or thin film.
b. Isolate an object from its outside environment with flexible membranes or thin films.

31. Porous Material

a. Make an object porous, or use supplementary porous elements (inserts, covers, etc.).
b. If an object is already porous, fill pores in advance with some substance.

32. Changing the Color

a. Change the colour of an object or its environment.
b. Change the degree of translucency of an
object or its environment.
c. Use colour additives to observe an object or process which is difficult to see.
d. If such additives are already used, employ luminescent traces or trace atoms.

33. Homogeneity

a. Objects interacting with the main object should be made out of the same material
(or material with similar properties) as the main object.

34. Rejecting and Regenerating Parts

a. After completing its function, or becoming useless, an element of an object is rejected (discarded, dissolved, evaporated, etc.) or modified during its work process.
b. Used-up parts of an object should be restored during its work.

35. Transformation of Properties

a. Change the physical state of the system.
b. Change the concentration or density.
c. Change the degree of flexibility.
d. Change the temperature or volume.

36. Phase Transition

a.Using the phenomena of the phase change (i.e., a change in volume, the liberation or
absorption of heat, etc.).

37. Thermal Expansion

a. Use expansion or contraction of material by changing its temperature.
b. Use various materials with different coefficients of thermal expansion.

38. Accelerated Oxidation

a. Make the transition from one level of oxidation to the next higher level:
1. Ambient air to oxygenated.
2. Oxygenated to oxygen.
3. Oxygen to ionized oxygen.
4. Ionized oxygen to ozoned oxygen.
5. Ozoned oxygen to ozone.
6. Ozone to singlet oxygen.

39. Inert Environment

a. Replace a normal environment with an inert one.
b. Introduce a neutral substance or additives into an object.
c. Carry out the process in a vacuum.

40. Composite Materials

a.Replace homogeneous materials with composite ones.

40 Invention Principles

This format for the 40 Inventive Principles and the accompanying examples was developed by Karen Tate and Ellen Domb for their class, “Practical Innovation.” which was the subject of the article “How to Help TRIZ Beginners Succeed”) in the April 1997 issue of the TRIZ Journal. TRIZ – Theory of Inventive Problem Solving

Principle 1. Segmentation

A. Divide an object into independent parts.
Replace mainframe computers with personal computers.
Replace a large truck with a truck and trailer.
Use a work breakdown structure for a large project.
B. Make an object easy to disassemble.
Modular furniture
Quick disconnect joints in plumbing
C. Increase the degree of fragmentation or segmentation.
Replace solid shades with Venetian blinds.
Use powdered welding metal instead of foil or rod to get better penetration of the joint.

Principle 2. Taking out

A. Separate an interfering part or property from an object, or single out the only necessary part (or property) of an object.
Locate a noisy compressor outside the building where compressed air is used.
Use fibre optics or a light pipe to separate the hot light source from the location where
light is needed.
Use the sound of a barking dog, without the dog, as a burglar alarm.

Principle 3. Local quality

A. Change an object’s structure from uniform to non-uniform, change an external environment (or external influence) from uniform to non-uniform.
Use a temperature, density, or pressure gradient instead of constant temperature, density
or pressure.
B. Make each part of an object function in conditions most suitable for its operation.
Lunch box with special compartments for hot and cold solid foods and for liquids
C. Make each part of an object fulfil a different and useful function.
Pencil with eraser
Hammer with nail puller
Multi-function tool that scales fish, acts as pliers, a wire stripper, a flat-blade
screwdriver, a Phillips screwdriver, manicure set, etc.

Principle 4. Asymmetry

A. Change the shape of an object from symmetrical to asymmetrical.
Asymmetrical mixing vessels or asymmetrical vanes in symmetrical vessels improve mixing (cement trucks, cake mixers, blenders).
Put a flat spot on a cylindrical shaft to attach a knob securely.
B. If an object is asymmetrical, increase its degree of asymmetry.
Change from circular O-rings to oval cross-section to specialized shapes to improve
sealing.
Use astigmatic optics to merge colours.

Principle 5. Merging

A. Bring identical or similar objects closer together (or merge them); assemble identical or similar parts to perform parallel operations.
Personal computers in a network.
Thousands of microprocessors in a parallel processor computer Vanes in a ventilation system
Electronic chips mounted on both sides of a circuit board or subassembly
B. Make operations contiguous or parallel; bring them together in time.
Link slats together in Venetian or vertical blinds.
Medical diagnostic instruments that analyze multiple blood parameters simultaneously
Mulching lawnmower.

Principle 6. Universality

A. Make a part or object perform multiple functions; eliminate the need for other parts.
The handle of a toothbrush contains toothpaste.
The child’s car safety seat converts to a stroller.
Mulching lawnmower (Yes, it demonstrates both Principles 5 and 6, Merging and
Universality.)
The team leader acts as recorder and timekeeper.
CCD (Charge-coupled device) with micro-lenses formed on the surface.

Principle 7. “Nested doll”

A. Place one object inside another; place each object, in turn, inside the other.
Measuring cups or spoons.
Russian dolls.
Portable audio system (microphone fits inside the transmitter, which fits inside amplifier case).
B. Make one part pass through a cavity in the other.
Extending radio antenna.
Extending pointer.
Zoom lens.
Seat belt retraction mechanism.
Retractable aircraft landing gear stow inside the fuselage (also demonstrates Principle 15, Dynamism).

Principle 8. Anti-weight

A. To compensate for the weight of an object, merge it with other objects that provide lift.
Inject foaming agent into a bundle of logs, to make it float better.
Use helium balloons to support advertising signs.
B. To compensate for the weight of an object, make it interact with the environment (e.g. use aerodynamic, hydrodynamic, buoyancy and other forces).
Aircraft wing shape reduces air density above the wing, increases density below the wing, to
create lift. (This also demonstrates Principle 4, Asymmetry.)
Vortex strips improve the lift of aircraft wings.
Hydrofoils lift ships out of the water to reduce drag.

Principle 9. Preliminary anti-action

A. If it will be necessary to do an action with both harmful and useful effects, this action
should be replaced with anti-actions o control harmful effects.
Buffer a solution to prevent harm from extremes of pH.
B. Use initial stresses in an object to oppose known undesirable working stresses.
Pre-stress rebar before pouring concrete.
Masking anything before harmful exposure: Use a lead apron on parts of the body not
being exposed to X-rays. Use masking tape to protect the part of an object not being
painted

Principle 10. Preliminary action

A. Perform, before it is needed, the required change of an object (either fully or partially).
Pre-pasted wallpaper.
Sterilize all instruments needed for a surgical procedure on a sealed tray.
B. Pre-arrange objects such that they can come into action from the most convenient place and without losing time for their delivery.
Kanban arrangements in a Just-In-Time factory.
Flexible manufacturing cell.

Principle 11. Beforehand cushioning

A. Prepare emergency means beforehand to compensate for the relatively low reliability of an object.
The magnetic strip on photographic film directs the developer to compensate for poor exposure.
Back-up parachute.
Alternate air system for aircraft instruments.

Principle 12. Equipotentiality

A. In a potential field, limit position changes (e.g. change operating conditions to eliminate the
need to raise or lower objects in a gravity field).
Spring-loaded parts delivery system in a factory.
Locks in a channel between 2 bodies of water (Panama Canal).
“Skillets” in an automobile plant that bring all tools to the right position (also
demonstrates Principle 10, Preliminary Action).

Principle 13. ‘The other way round’

A. Invert the action(s) used to solve the problem (e.g. instead of cooling an object, heat it).
To loosen stuck parts, cool the inner part instead of heating the outer part.
Bring the mountain to Mohammed, instead of bringing Mohammed to the mountain.
B. Make movable parts (or the external environment) fixed, and fixed parts movable).
Rotate the part instead of the tool.
Moving sidewalk with standing people.
Treadmill (for walking or running in place).
C. Turn the object (or process) ‘upside down.
Turn an assembly upside down to insert fasteners (especially screws).
Empty the grain from containers (ship or railroad) by inverting them.

Principle 14. Spheroidality – Curvature

A. Instead of using rectilinear parts, surfaces, or forms, use curvilinear ones; move from flat surfaces to spherical ones; from parts shaped as a cube (parallelepiped) to ball-shaped structures.
Use arches and domes for strength in architecture.
B. Use rollers, balls, spirals, domes.
Spiral gear (Nautilus) produces continuous resistance for weight lifting.
Ballpoint and roller point pens for smooth ink distribution
C. Go from linear to rotary motion, use centrifugal forces.
Produce linear motion of the cursor on the computer screen using a mouse or a trackball.
Replace wringing clothes to remove water with spinning clothes in a washing machine.
Use spherical casters instead of cylindrical wheels to move furniture.

Principle 15. Dynamics

A. Allow (or design) the characteristics of an object, external environment, or process to
change to be optimal or to find an optimal operating condition.
Adjustable steering wheel (or seat, or back support, or mirror position…)
B. Divide an object into parts capable of movement relative to each other.
The “butterfly” computer keyboard, (also demonstrates Principle 7, “Nested doll”.)
C. If an object (or process) is rigid or inflexible, make it movable or adaptive.
The flexible boroscope for examining engines
The flexible sigmoidoscope, for medical examination.

Principle 16. Partial or excess ve actions

A. If 100 per cent of an object is hard to achieve using a given solution method, the problem may be considerably easier to solve by using ‘slightly less’ or ‘slightly more’ of the same method.
Overspray when painting, then remove excess. (Or, use a stencil–this is an application of
Principle 3, Local Quality and Principle 9, Preliminary anti-action).
Fill, then “top off” when filling the gas tank of your car.

Principle 17. Another dimension

A. To move an object in two- or three-dimensional space.
Infrared computer mouse moves in space, instead of on a surface, for presentations.
A Five-axis cutting tool can be positioned where needed.
B. Use a multi-story arrangement of objects instead of a single-story arrangement.
Cassette with 6 CD’s to increase music time and variety
Electronic chips on both sides of a printed circuit board
Employees “disappear” from the customers in a theme park, descend into a tunnel, and
walk to their next assignment, where they return to the surface and magically reappear.
C. Tilt or re-orient the object, lay it on its side.
Dump truck.
D. Use ‘another side’ of a given area.
Stack microelectronic hybrid circuits to improve density.

Principle 18. Mechanical vibration

A. Cause an object to oscillate or vibrate.
Electric carving knife with vibrating blades
B. Increase its frequency (even up to the ultrasonic).
Distribute powder with vibration.
C. Use an object’s resonant frequency.
Destroy gall stones or kidney stones using ultrasonic resonance.
D. Use piezoelectric vibrators instead of mechanical ones.
Quartz crystal oscillations drive high accuracy clocks.
E. Use combined ultrasonic and electromagnetic field oscillations.
Mixing alloys in an induction furnace

Principle 19. Periodic action

A. Instead of continuous action, use periodic or pulsating actions.
Hitting something repeatedly with a hammer
Replace a continuous siren with a pulsed sound.
B. If an action is already periodic, change the periodic magnitude or frequency.
Use Frequency Modulation to convey information, instead of Morse code.
Replace a continuous siren with a sound that changes amplitude and frequency.
C. Use pauses between impulses to perform a different action.
In cardio-pulmonary respiration (CPR) breathe after every 5 chest compressions.

Principle 20. Continuity of useful action

A. Carry on work continuously; make all parts of an object work at full load, all the time.
Flywheel (or hydraulic system) stores energy when a vehicle stops, so the motor can keep running at optimum power.
Run the bottleneck operations in a factory continuously, to reach the optimum pace. (From the theory of constraints, or task time operations).
B. Eliminate all idle or intermittent actions or work.
Print during the return of a printer carriage–dot matrix printer, daisy wheel printers,
inkjet printers.

Principle 21. Skipping

A. Conduct a process, or certain stages (e.g. destructible, harmful or hazardous operations) at high speed.
Use a high-speed dentist’s drill to avoid heating tissue.
Cut plastic faster than heat can propagate in the material, to avoid deforming the shape.

Principle 22. “Blessing in disguise” or “Turn Lemons into Lemonade”

A. Use harmful factors (particularly, harmful effects of the environment or surroundings) to achieve a positive effect.
Use waste heat to generate electric power.
Recycle waste (scrap) material from one process as raw materials for another.
B. Eliminate the primary harmful action by adding it to another harmful action to resolve the problem.
Add a buffering material to a corrosive solution.
Use a helium-oxygen mix for diving, to eliminate both nitrogen narcosis and oxygen
poisoning from the air and other nitrox mixes.
C. Amplify a harmful factor to such a degree that it is no longer harmful.
Use a backfire to eliminate the fuel from a forest fire.

Principle 23. Feedback

A. Introduce feedback (referring back, cross-checking) to improve a process or action.
Automatic volume control in audio circuits.
The signal from gyrocompass is used to control simple aircraft autopilots.
Statistical Process Control (SPC) — Measurements are used to decide when to modify a
process. (Not all feedback systems are automated!).
Budgets –Measurements are used to decide when to modify a process.
B. If feedback is already used, change its magnitude or influence.
Change sensitivity of autopilot when within 5 miles of an airport.
Change sensitivity of a thermostat when cooling vs. heating, since it uses energy less
efficiently when cooling.
Change a management measure from budget variance to customer satisfaction.

Principle 24. ‘Intermediary’

A. Use an intermediary carrier article or intermediary process.
Carpenter’s nail set, used between the hammer and the nail.
B. Merge one object temporarily with another (which can be easily removed).
Potholder to carry hot dishes to the table.

Principle 25. Self-service

A. Make an object serve itself by performing auxiliary helpful functions
A soda fountain pump that runs on the pressure of the carbon dioxide used to “fizz” the
drinks. This assures that drinks will not be flat, and eliminates the need for sensors.
Halogen lamps regenerate the filament during use–evaporated material is re-deposited.
To weld steel to aluminium, create an interface from alternating thin strips of the 2
materials. Cold weld the surface into a single unit with steel on one face and copper on
the other, then use normal welding techniques to attach the steel object to the interface,
and the interface to the aluminium. (This concept also has elements of Principle 24,
Intermediary, and Principle 4, Asymmetry.)
B. Use waste resources, energy, or substances.
Use heat from a process to generate electricity: “Co-generation”.
Use animal waste as fertilizer.
Use food and lawn waste to create compost.

Principle 26. Copying

A. Instead of an unavailable, expensive, fragile object, use simpler and inexpensive copies.
Virtual reality via computer instead of an expensive vacation
Listen to an audiotape instead of attending a seminar.
B. Replace an object, or process with optical copies.
Do surveying from space photographs instead of on the ground.
Measure an object by measuring the photograph.
Make sonograms to evaluate the health of a fetus, instead of risking damage by direct
testing.
C. If visible optical copies are already used, move to infrared or ultraviolet copies.
Make images in infrared to detect heat sources, such as diseases in crops, or intruders in a security system.

Principle 27. Cheap short-living objects

A. Replace an inexpensive object with a multiple of inexpensive objects, comprising certain qualities (such as service life, for instance).
Use disposable paper objects to avoid the cost of cleaning and storing durable objects.
Plastic cups in motels, disposable diapers, many kinds of medical supplies.

Principle 28. Mechanics substitution

A. Replace a mechanical means with a sensory (optical, acoustic, taste or smell) means.
Replace a physical fence to confine a dog or cat with an acoustic “fence” (signal audible
to the animal).
Use a bad-smelling compound in natural gas to alert users to leakage, instead of a
mechanical or electrical sensor.
B. Use electric, magnetic and electromagnetic fields to interact with the object.
To mix 2 powders, electrostatically charge one positive and the other negative. Either use fields to direct them, or mix them mechanically and let their acquired fields cause the grains of powder to pair up.
C. Change from static to movable fields, from unstructured fields to those having structure.
Early communications used omnidirectional broadcasting. We now use antennas with very detailed structures of the pattern of radiation.
D. Use fields in conjunction with field-activated (e.g. ferromagnetic) particles.
Heat a substance containing ferromagnetic material by using a varying magnetic field.
When the temperature exceeds the Curie point, the material becomes paramagnetic and
no longer absorbs heat.

Principle 29. Pneumatics and hydraulics

A. Use gas and liquid parts of an object instead of solid parts (e.g. inflatable, filled with
liquids, air cushion, hydrostatic, hydro-reactive).
Comfortable shoe sole inserts filled with gel.
Store energy from decelerating a vehicle in a hydraulic system, then use the stored
energy to accelerate later.

Principle 30. Flexible shells and thin films

A. Use flexible shells and thin films instead of three dimensional structures
Use inflatable (thin film) structures as winter covers on tennis courts.
B. Isolate the object from the external environment using flexible shells and thin films.
Float a film of bipolar material (one end hydrophilic, one end hydrophobic) on a reservoir
to limit evaporation.

Principle 31. Porous materials

A. Make an object porous or add porous elements (inserts, coatings, etc.).
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.
Use a porous metal mesh to wick excess solder away from a joint.
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.
Use safe lights in a photographic darkroom.
B. Change the transparency of an object or its external environment.
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).
Make the container out of the same material as the contents, to reduce chemical reactions.
Make diamond cutting tools 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.
Use a dissolving capsule for medicine.
Sprinkle water on cornstarch-based packaging and watch it reduce its volume by more
than 1000X!
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.
Self-sharpening lawn mower blades.
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. Change an object’s physical state (e.g. to a gas, liquid, or solid.
Freeze the liquid centers of filled candies, then dip in melted chocolate, instead of
handling the messy, gooey, hot liquid.
Transport oxygen or nitrogen or petroleum gas as a liquid, instead of a gas, to reduce
volume.
B. Change the concentration or consistency.
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.
Use adjustable dampers to reduce the noise of parts falling into a container by restricting the motion of the walls of the container.
Vulcanize rubber to change its flexibility and durability.
D. Change the temperature.
Raise the temperature above the Curie point to change a ferromagnetic substance to a
paramagnetic substance.
Raise the temperature of food to cook it. (Changes taste, aroma, texture, chemical
properties, etc.)
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.).
Water expands when frozen, unlike most other liquids. Hannibal is reputed to have used
this phenomenon 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 that could be pushed aside.
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.
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.
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.
Scuba diving with Nitrox or other non-air mixtures for extended endurance
B. Replace enriched air with pure oxygen.
Cut at a higher temperature using an oxy-acetylene torch.
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.
Ionize air to trap pollutants in an air cleaner.
E. Replace ozonized (or ionized) oxygen with ozone.
Speed up chemical reactions by ionizing the gas before use.

Principle 39. Inert atmosphere

A. Replace a normal environment with an inert one.
Prevent degradation of a hot metal filament by using an argon atmosphere.
B. Add neutral parts or inert additives to an object.
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.
Composite epoxy resin/carbon fibre golf club shafts are lighter, stronger, and more
flexible than metal. The same may be applied to aeroplane parts.
Fibreglass surfboards are lighter and more controllable and easier to form into a variety
of shapes than wooden ones.

 

40 Invention Principles

by Oxford Creativity  

TRIZ – Theory of Inventive Problem Solving

Principle 1 Segmentation

A. Divide an object into independent parts
− Different focal length lenses for a camera
− Gator-grip socket spanner
− Multi-pin connectors
− Multiple pistons in an internal combustion engine
− Multi-engined aircraft
− Stratification of different constituents inside a chemical process vessel
B. Make an object sectional – easy to assemble or disassemble
− Rapid-release fasteners for bicycle saddle/wheel/etc
− Quick disconnect joints in plumbing and hydraulic systems
− Single fastener V-band clamps on flange joints
− Loose-leaf paper in a ring binder
C. Increase the degree of fragmentation or segmentation
− Multiple control surfaces on aerodynamic structures
− 16 and 24 valves versus 8 valve internal combustion engines
− Multi-zone combustion system
− Build up a component from layers (e.g. stereo-lithography, welds, etc)

Principle 2 Taking out

A. Extract the disturbing part or property from an object
− Non-smoking areas in restaurants or in railway carriages
− Children-only areas in public places and home
− Sunday school
− Public bars and lounge bars in pubs
− Women or men only bars/waiting rooms
− Air Conditioning in the room where you want it with the noise of the
system outside the room
(The contradiction here is noise vs coolness- the cooler it gets the noisier it
gets- this solves the contradiction by putting the noise elsewhere )
B. Extract the only necessary part (or property) of an object
− Scarecrow
− Sound of a barking dog (with no dog) as a burglar alarm
− Economy class on planes (travel but no-frills)
(This involves understanding all the functionality and selecting only what you
want- e.g. windows provide ventilation and light – with air conditioning you
may not need windows which open)

Principle 3 Local quality

A. Change of an object’s structure from uniform to non-uniform
− Reduce drag on aerodynamic surfaces by adding riblets or ‘shark-skin’
protrusions
− Moulded hand grips on tools
− Drink cans shaped to facilitate stable stacking
− Material surface treatments /coatings – plating,
− Erosion / corrosion protection, case hardening, non-stick, etc
B. Change an action or an external environment (or external influence) from
uniform to non-uniform
− Introduce turbulent flow around an object to alter heat transfer
properties
− Strobe lighting
− Take account of extremes of weather conditions when designing
outdoor systems
− Use a gradient instead of constant temperature, density, or pressure
C. Make each part of an object function in conditions most suitable for its
operation
− Freezer compartment in the refrigerator
− Different zones in the combustion system of an engine
− Night-time adjustment on a rear-view mirror
− Lunch box with special compartments for hot and cold solid foods and
for liquids
D. Make each part of an object fulfil a different and/or complementary useful
function
− Swiss-Army knife
− Combined can and bottle opener
− Sharp and the blunt end of a drawing pin
− Rubber on the end of a pencil
− Hammer with nail puller

Principle 4 Asymmetry

A. Change the shape or properties of an object from symmetrical to
asymmetrical
− Asymmetrical funnel allows a higher flow rate than normal funnel
− Put a flat spot on a cylindrical shaft to attach a locking feature
− Oval and complex shaped O-rings
− Coated glass or paper
− Electric Plug
− Introduction of angled or scarfed geometry features on the component
edges
− Cutaway on a guitar improves access to high notes
− Spout of a jug
− Cam
− Ratchet
− Aerofoil – asymmetry generates lift
− Eccentric drive
− Keys
B. Change the shape of an object to suit external asymmetries
(e.g. ergonomic features)
− Human-shaped seating, etc
− Design for left and right-handed users
− Finger and thumb grip features on objects
− Spectacles
− Car steering system compensates for camber in the road
− Wing design compensated for asymmetric flow produced by the propeller
− Turbomachinery design for boundary layer flows (‘end-bend’)
C. If an object is asymmetrical, increase its degree of asymmetry
− Use of variable control surfaces to alter lift properties of an aircraft wing
− Special connectors with complex shape/pin configurations to ensure
correct assembly
− Introduction of several different measurement scales on a ruler

Principle 5 Merging

A. Bring closer together (or merge) identical or similar objects or operations in
space
− Automatic rifle/machine gun
− Multi-colour ink cartridges
− Multi-blade razors
− Bi-focal lens spectacles
− Double/triple glazing
− Strips of staples
− Catamaran/trimaran
B. Make objects or operations contiguous or parallel; bring them together in
time
− Combine harvester
− Manufacture cells
− Grass collector on a lawn-mower
− Mixer taps
− Pipe-lined computer processors perform different stages in a calculation
simultaneously
− Vector processors perform the same process on several sets of data in a
single pass
− Fourier analysis – integration of many sine curves

Principle 6 Universality

A. Make an object perform multiple functions; eliminate the need for other
parts
− Child’s car safety seat converts to a pushchair
− Home entertainment centre
− Swiss Army knife
− Grill in a microwave oven
− CD used as a storage medium for multiple data types
− Cleaning strip at beginning of a cassette tape cleans tape heads
− Cordless drill also acts as screwdriver, sander, polisher, etc

Principle 7 Nested Doll

A. Place one object inside another
− Retractable aircraft under-carriage
− Voids in 3D structures
− Injected cavity-wall insulation
− Paint-brush attached to inside of lid of nail-varnish, etc
− Lining inside a coat
B. Place multiple objects inside others
− Nested tables
− Telescope
− Measuring cups or spoons
− Stacking chairs
− Multi-layer erosion/corrosion coatings
C. Make one part pass (dynamically) through a cavity in the other
− Telescopic car aerial
− Retractable power-lead in vacuum cleaner
− Seat belt retraction mechanism
− Tape measure

Principle 8 Anti-Weight

A. To compensate for the weight of an object, merge it with other objects that
provide lift
− Kayak with foam floats built into hull cannot sink
− Aerostatic aeroplane contains lighter-than-air pockets
− Hot air or helium balloon
− Swim-bladder inside a fish
− Flymo cutting blade produces lift
B. To compensate for the weight of an object, make it interact with the
environment (use aerodynamic, hydrodynamic, buoyancy and other forces)
− Vortex generators improve the lift of aircraft wings
− Wing-in-ground effect aircraft
− Hydrofoils lift ships out of the water to reduce drag
− Make use of centrifugal forces in rotating systems (e.g. Watt governor)
− Maglev train uses magnetic repulsion to reduce friction
Principle 9 Prior Counteraction
A. When it is necessary to perform an action with both harmful and useful
effects, this should be replaced with counteractions to control harmful effects
− Make clay pigeons out of ice or dung – they just melt away
− Masking objects before harmful exposure: use a lead apron for X-rays,
use masking tape when painting difficult edges etc.
− Predict effects of signal distortion – compensate before transmitting
− Buffer a solution to prevent harm from extremes of pH
B. Create beforehand stresses in an object that will oppose known
undesirable working stresses later on
− Pre-stress rebar before pouring concrete
− Pre-stressed bolts
− Decompression chamber to prevent divers getting the bends

Principle 10 Prior Action

A. Perform the required change of an object in advance
− Pre-pasted wallpaper
− Sterilize all instruments needed for a surgical procedure
− Self-adhesive stamps
− Holes cut before sheet-metal part formed
− Pre-impregnated carbon fibre reduces lay-up time and improves
“wetting”
B. Pre-arrange objects such that they can come into action from the most
convenient place and without losing time for their delivery
− Manufacture flow-lines
− Pre-deposited blade in a surgery cast facilitates removal
− Car jack, wheel brace, and spare tyre stored together
− Collect all the tools and materials for the job before starting

Principle 11 Cushion in Advance

A. Prepare emergency means beforehand to compensate for the relatively low
reliability of an object (‘belt and braces’)
− Multi-channel control system
− Air-bag in a car / Spare wheel / Battery back-up / Back-up parachute
− Pressure relief valve
− Emergency lighting circuit
− Automatically save operations performed by computer programs
− Crash barriers on motorways
− ‘Touch-down’ bearing in the magnetic bearing system

Principle 12 Equipotentiality

A. If an object has to be raised or lowered, redesign the object’s environment
so the need to raise or lower is eliminated or performed by the environment
− Canal locks
− Spring-loaded parts delivery system in a factory
− Mechanic’s pit in a garage means car does not have to be lifted
− Place a heavy object on ice, and let ice melt in order to lower it
− Angle-poise lamp; changes in gravitational potential stored in springs
− Descending cable cars balance the weight of ascending cars

Principle 13 The Other Way Round

A. Invert the action used to solve the problem
− To loosen stuck parts, cool the inner part instead of heating the outer
part
− Vacuum casting
− Rotary engines
− Test pressure vessel by varying pressure outside rather than inside
− Test seal on a liquid container by filling with pressurised air and
immersing in liquid; trails of bubbles are easier to trace than slow liquid
leaks
B. Make movable parts (or the external environment) fixed, and fixed parts
movable
− Hamster wheel
− Escalator
− Rotate the part instead of the tool
− Wind tunnels
− Moving sidewalk with standing people
− Drive-through restaurant or bank
C. Turn the object (or process) ‘upside down.
− Clean bottles by inverting and injecting water from below
− Turn an assembly upside down to insert fasteners

Principle 14 Spheroidality – Curvature

A. Move from flat surfaces to spherical ones and from parts shaped as a cube
(parallelepiped) to ball-shaped structures
− Use arches and domes for strength in architecture
− Introduce fillet radii between surfaces at different angles
− Introduce stress-relieving holes at the ends of slots
− Change curvature on lens to alter light deflection properties
B. Use rollers, balls, spirals
− Spiral gear (Nautilus) produces continuous resistance for weight lifting
− Ballpoint and roller point pens for smooth ink distribution
− Use spherical casters instead of cylindrical wheels to move furniture
− Archimedes screw
C. Go from linear to rotary motion (or vice versa)
− Rotary actuators in the hydraulic system
− Switch from reciprocating to a rotary pump
− Push/pull versus rotary switches (e.g. lighting dimmer switch)
− Linear motors
− Linear versus rotating tracking arm on a record turntable ensures
the constant angle of the stylus relative to the groove
− Screw-thread versus nail
D. Use centrifugal forces
− Centrifugal casting for even wall thickness structures
− Spin components after painting to remove excess paint
− Remove water from clothes with a spin dryer rather than a mangle
− Separate chemicals with different density properties using a centrifuge
− Watt governor
− Vortex/cyclone separates different density objects

Principle 15 Dynamics

A. Change the object (or outside environment) for optimal performance at
every stage of operation
− Gel fillings inside the seat allow it to adapt to the user
− Adjustable steering wheel (or seat, or back support, or mirror position…)
− Shape memory alloys/polymers
− Racing car suspension adjustable for different tracks and driving
techniques
− Car handbrake adjustable to account for brake pad wear
− Telescopic curtain rail – “one size fits all”
B. Divide an object into parts capable of movement relative to each other
− Bifurcated bicycle saddle
− Articulated lorry
− Folding chair/mobile phone/laptop/etc
− Collapsible structures
− Brush seals
C. Change from immobile to mobile
− Bendy drinking straw
− Flexible joint
− Collapsible hose is flexible in use and has added flexibility of crosssection to make it easier to store
D. Increase the degree of free motion
− Use of different stiffness fibres in toothbrush – easily deflected at the
edges to prevent gum damage, hard in the middle
− Flexible drive allows motion to be translated around bends
− Loose sand inside truck tyre gives it self-balancing properties at speed
− Add joints to the robot arm to increase motion possibilities

Principle 16 Partial or Excessive Action

A. If you can’t achieve 100 percent of a desired effect – then go for more or
less
− Overspray when painting, then remove excess
− Fill, then “top off” when pouring a pint of Guinness
− Shrinkwrapping process uses plastic deformation of wrapping to
accommodate variations in vacuum pressure
− ‘Roughing’ and ‘Finish’ machining operations
− Over-fill holes with plaster and then rub back to smooth

Principle 17 Another Dimension

A. Move into an additional dimension – from one to two – from two to three
− Coiled telephone wire
− Curved bristles on a brush
− Pizza-box with ribbed (as opposed to flat) base
− Spiral staircase uses less floor area
− Introduction of down and up slopes between stations on railways reduces
overall power requirements
B. Go from the single storey or layer to multi-storey or multi-layered
− Player with many CDs
− Stacked or multi-layered circuit boards
− Multi-storey office blocks or car-parks
C. Incline an object, lay it on its side
− Cars on road transporter inclined to save space
D. Use the other side
− Press a groove onto both sides of a record
− Mount electronic components on both sides of a circuit board
− Print text around the rim of a coin
− Paper clip – works by pressing both sides of the paper together
Principle 18 Mechanical Vibration
A. Cause an object to oscillate or vibrate
− Electric carving knife with vibrating blades
− Shake/stir the paint to mix before applying
− Hammer drill
− Vibration exciter removes voids from poured concrete
− Vibrate during sieving operations to improve throughput
− Musical instrument
B. Increase its frequency (even up to the ultrasonic)
− Dog-whistle (transmit sound outside human range)
− Ultrasonic cleaning
− Non-destructive crack detection using ultrasound
C. Use an object’s resonant frequency
− Destroy gallstones or kidney stones using ultrasonic resonance
− Bottle cleaning by pulsing water jet at a resonant frequency of bottles
− Tuning fork
− Increase the action of a catalyst by vibrating it at its resonant frequency
D. Use piezoelectric vibrators instead of mechanical ones
− Quartz crystal oscillations drive high accuracy clocks
− Piezoelectric vibrators improve fluid atomisation from a spray nozzle
− Optical phase modulator
E. Use combined ultrasonic and electromagnetic field oscillations
− Mixing alloys in an induction furnace
− Sono-chemistry
− Ultrasonic drying of films – combine ultrasonic with a heat source

Principle 19 Periodic Action

A. Instead of continuous action, use periodic or pulsating actions
− Hitting something repeatedly with a hammer
− Pile drivers and hammer drills exert far more force for a given weight
− Replace a continuous siren with a pulsed sound
− Pulsed bicycle lights make cyclists more noticeable to drivers
− Pulsed vacuum cleaner suction improves collection performance
− Pulsed water jet cutting
− ABS car braking systems
B. If an action is already periodic, change the periodic magnitude or
frequency
− Improve a pulsed siren with changing amplitude and frequency
− Dots and dashes in Morse Code transmissions
− Use AM, FM, PWM to transmit information
C. Use pauses between actions to perform a different action
− Clean barrier filters by back-flushing them when not in use
− Inkjet printer cleans heads between passes
− Brush between suction pulses in vacuum cleaner
− Multiple conversations on the same telephone transmission line
− Use of energy storage means – e.g. batteries, fly-wheels, etc

Principle 20 Continuity of Useful Action

A. Carry on work without a break. All parts of an object operating
constantly at full capacity
− Flywheel stores energy when a vehicle stops, so the motor can keep
running at optimum power
− Constant output gas turbine in a hybrid car, or APU in aircraft, runs at
highest efficiency all the time it is switched on
− Constant speed / variable pitch propeller
− Self-tuning engine – constantly tunes itself to ensure maximum efficiency
− Heart pacemaker
− Improve the composting process by continuously turning material
− Continuous glass or steel production
B. Eliminate all idle or intermittent motion
− Self-cleaning / self-emptying filter eliminates down-time
− Print during the return of a printer carriage – dot matrix printer, daisy
wheel printers, inkjet printers
− Digital storage media allow ‘instant’ information access
− Kayaks use double-ended paddle to utilise recovery stroke
− Computer operating systems utilise idle periods to perform necessary
housekeeping tasks

Principle 21 Rushing Through

A. Conduct a process, or certain stages of it (e.g. destructible, harmful or
hazardous operations) at high speed
− Cut plastic faster than heat can propagate in the material, to avoid
deforming the shape
− Shatter toffee with a hammer blow
− Drop forge
− Flash photography
− Super-critical shaft – run through resonant modes quickly
− Bikini waxing (ouch!)

Principle 22 Blessing in Disguise

A. Use harmful factors (particularly, harmful effects of the environment or
surroundings) to achieve a positive effect
− Use waste heat to generate electric power
− Recycle scrap material as raw materials for another – e.g. chipboard
− Vaccination
− Lower body temperature to slow metabolism during operations
− Composting
− Use centrifugal energy in rotating shaft to do something useful – e.g.
seal, or modulate cooling air
− Use pressure differences to help rather than hinder seal performance
B. Eliminate the primary harmful action by adding it to another harmful
action to resolve the problem
− Add a buffering material to a corrosive solution (e.g. an alkali to an acid,
or vice versa)
− Use a helium-oxygen mix for diving, to eliminate both nitrogen narcosis
and oxygen poisoning from the air and other nitrox mixes
− Use gamma rays to detect positron emissions from explosives
C. Amplify a harmful factor to such a degree that it is no longer harmful
− Use a backfire to eliminate the fuel from a forest fire
− Use explosives to blow out an oil-well fire
− Laser-knife cauterises skin/blood vessels as it cuts

Principle 23 Feedback

A. Introduce feedback to improve a process or action
− Automatic volume control in audio circuits
− Signal from gyrocompass is used to control simple aircraft autopilots
− Engine management system based on exhaust gas levels is more
efficient than carburettor
− Thermostat controls temperature accurately
− Statistical Process Control – measurements are used to decide when to
modify a process
− Feedback turns inaccurate op-amp into a useable accurate amplifier
B. If feedback is already used, change its magnitude or influence in
accordance with operating conditions
− Change sensitivity of autopilot when within 5 miles of an airport
− Change sensitivity of a thermostat when cooling vs. heating, since it
uses energy less efficiently when cooling
− Use proportional, integral and/or differential control algorithm
combinations

Principle 24 Intermediary

A. Use an intermediary carrier article or intermediary process
− Play the guitar with a plectrum
− Use a chisel to control the rock breaking/sculpting process
− Dwell period during a manufacture process operation
B. Merge one object temporarily with another (which can be easily removed)
− Gloves to get hot dishes out of an oven
− Joining papers with a paper clip
− Introduction of catalysts into chemical reaction
− Abrasive particles enhance water jet cutting
− Bouquet garni in cooking

Principle 25 Self-Service

A. An object must service itself by performing auxiliary helpful functions
− A soda fountain pump that runs on the pressure of the carbon dioxide
used to carbonate the drinks. If it won’t fizz it’s empty!
− Halogen lamps regenerate the filament – evaporated material is redeposited
− Self-aligning / self-adjusting seal
− Self-cleaning oven / glass / material
− Abradable materials used in gas turbines such that initial running-in ‘cuts’
optimum seals into the lining
B. Use waste resources, energy, or substances
− Use heat from a process to generate electricity: co-generation
− Use animal waste as fertilizer
− Use food and lawn waste to create compost
− Use pressure difference to reinforce seal action

Principle 26 Copying

A. Replace unavailable, expensive or fragile object with available or
inexpensive copies
− Imitation jewellery
− Astroturf
− Crash test dummy
B. Replace an object, or process with optical copies
− Do surveying from space photographs instead of on the ground
− Measure an object by scaling measurements from a photograph
− Virtual reality / Virtual mock-ups / electronic pre-assembly modelling
C. If visible optical copies are used, move to infrared or ultraviolet copies
− Make images in infrared to detect heat sources, such as diseases in
crops, or intruders in a security system
− Use UV as a non-destructive crack detection method
− UV light used to attract flying insects into the trap

Principle 27 Cheap Short-Living Objects

A. Replace an expensive object with a multiple of inexpensive objects,
compromising certain qualities, such as service life
− Disposable nappies / paper-cups / plates / cameras / torches etc
− Matches versus lighters
− Throw-away cigarette lighters
− Sacrificial coatings / components

Principle 28 Replace Mechanical System

A. Replace a mechanical system with a sensory one
− Replace a physical barrier with an acoustic one (audible to animals)
− Add a bad smell to natural gas to alert users to leaks
− Finger-print/retina/etc scan instead of a key
− Voice-activated telephone dialling
B. Use electric, magnetic and electromagnetic fields to interact with the
object
− To mix 2 powders, electrostatically charge one positive and the other
negative
− Electrostatic precipitators separate particles from the airflow
− Improve the efficiency of paint-spraying by oppositely charging the paint droplets and objects to be painted
− Magnetic bearings
− Field activated switches
C. Replace stationary fields with moving; unstructured fields with
structured
− Early communications used Omni-directional broadcasting. We now use
antennas with the very detailed structure of the pattern of radiation
− Magnetic Resonance Imaging (MRI) scanner
D. Use fields in conjunction with field-activated (e.g. ferromagnetic)
particles
− Heat a substance containing ferromagnetic material by using a varying magnetic field. When the temperature exceeds the Curie point, the material becomes paramagnetic, and no longer absorbs heat
− Magneto-rheological effect – uses ferromagnetic particles and variable
magnetic field to alter the viscosity of a fluid
− Ferro-magnetic catalysts
− Ferro-fluids – e.g. Magnatec oil – stay attached to surfaces requiring
lubrication

Principle 29 Pneumatics and Hydraulics

A. Use gas and liquid parts of an object instead of solid parts (e.g.
inflatable, filled with liquids, air cushion, hydrostatic, hydro-reactive)
− Transition from mechanical to hydraulic or pneumatic drive
− Inflatable furniture / mattress etc
− Gel-filled saddle adapts to the user
− Hollow section O-rings
− Hovercraft
− Gas bearings
− Acoustic panels incorporating Helmholtz resonators

Principle 30 Flexible Membranes/Thin Films

A. Use flexible shells and thin films instead of three-dimensional structures
− Use inflatable (thin film) structures
− Taut-liner trucks
− Tarpaulin car cover instead of the garage
− Store energy in stretchable bags – accumulators in a hydraulic system
B. Isolate the object from its external environment using flexible membranes
− Bubble-wrap
− Bandages/plasters
− Teabag
− Shrinkwrapping

Principle 31 Porous Materials

A. Make an object porous or add porous elements (inserts, coatings, etc.)
− Drill holes in a structure to reduce the weight
− Cavity wall insulation
− Transpiration film cooled structures
− Foam metals
− Use sponge-like structures as fluid absorption media
B. If an object is already porous, use the pores to introduce a useful
substance or function
− Use a porous metal mesh to wick excess solder away from a joint
− Store hydrogen in the pores of a palladium sponge. (Fuel “tank” for the
hydrogen car – much safer than storing hydrogen gas)
− Desiccant in polystyrene packing materials
− Medicated swabs/dressings

Principle 32 Colour Change

A. Change in the colour of an object or its external environment
− Use safe lights in a photographic darkroom
− Use colour-changing thermal paint to measure temperature
− Plastic spoon which changes colour when hot – for baby food
− Temperature-sensitive dyes used on food product labels to indicate
when the desired serving temperature has been achieved
− Electrochromic glass
− Light-sensitive glasses
− Camouflage
− Dazzle camouflage used on World War 1 ships
− Employ interference fringes on surface structures to change colour (as in butterfly wings, etc)
B. Change the transparency of an object or its external environment
− Use photolithography to change transparent material to a solid mask for
semiconductor processing
− Light-sensitive glass
C. In order to improve the observability of things that are difficult to see, use coloured additives or luminescent elements
− Fluorescent additives used during UV spectroscopy
− UV marker pens are used to help identify stolen goods
− Use opposing colours to increase visibility – e.g. butchers use green decoration to make the red in meat look redder
D. Change the emissivity properties of an object subject to radiant heating
− Use of black and white coloured panels to assist thermal management
on space vehicles
− Use of parabolic reflectors in solar panels to increase energy capture
− Paint object with high emissivity paint in order to be able to measure its temperature with a calibrated thermal imager

Principle 33 Homogeneity

A. Objects interacting with the main object should be of the same material (or material with identical properties)
− Container made of the same material as its contents, to reduce chemical reactions
− Friction welding requires no intermediary material between the two surfaces to be joined
− Temporary plant pots made out of compostable material
− Human blood transfusions/transplants, use of bio-compatible materials
− Make ice cubes out of the same fluid as the drink they are intended to
cool
− Join wooden components using (wood) dowel joints

Principle 34 Discarding and Recovering

A. After completing their function (or becoming useless) reject objects, make
them go away, (discard them by dissolving, evaporating, etc) or modify during
the process
− Dissolving capsule for medication.
− Bio-degradable containers, bags etc.
− Casting processes – lost-wax, sand, etc.
− During firing of a rocket, foam protection is used on some elements; this evaporates in space when shock-absorbance is no longer required
B. Restore consumable / used up parts of an object during operation
− Self-sharpening blades – knives/lawn-mowers etc
− Strimmer dispenses more wire automatically after a breakage
− Self-tuning automobile engines
− Propelling pencil
− Automatic rifle

Principle 35 Parameter Change

A. Change the physical state (e.g. to a gas, liquid, or solid)
− Transport oxygen or nitrogen or petroleum gas as a liquid, instead of gas, to reduce the volume
B. Change the concentration or density
− Liquid soap
− Abradable linings used for gas-turbine engine seals
C. Change the degree of flexibility
− Vulcanize rubber to change its flexibility and durability
− Compliant brush seals rather than labyrinth or other fixed geometry
seals
D. Change the temperature or volume
− Raise the temperature above the Curie point to change a ferromagnetic substance to a paramagnetic substance
− Cooking/baking etc.
E. Change the pressure
− Pressure cooker cooks more quickly and without losing flavours
− Electron beam welding in a vacuum
− Vacuum packing of perishable goods
F. Change other parameters
− Shape memory alloys/polymers
− Use Curie point to alter magnetic properties
− Thixotropic paints / gels etc.
− Use high conductivity materials – e.g. carbon fibre

Principle 36 Phase Transition

A. Use phenomena of phase transitions (e.g. volume changes, loss or
absorption of heat, etc.)
− Latent heat effects in melting/boiling
− Soak rocks in the water, then freezing causes water to expand – thus
opening fissures in the rock, making it easier to break
− Heat pumps use the heat of vaporization and heat of condensation of a
closed thermodynamic cycle to do useful work
− Volume expansion during the water-to-steam transition
− Superconductivity

Principle 37 Thermal Expansion

A. Use thermal expansion, or contraction, of materials
− 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
− Metal tie-bars used to straighten buckling walls on old buildings
− Thermal switch/cut-out
− Shape memory alloys/polymers
− Shrink-wrapping
B. Use multiple materials with different coefficients of thermal expansion
− Bi-metallic strips used for thermostats, etc
− Two-way shape memory alloys
− Passive blade tip clearance control in gas turbine engines
− Combine materials with positive and negative thermal expansion
coefficients to obtain alloys with zero (or specifically tailored) expansion
properties – e.g. Cerro-tru alloy used in the mounting and location of fragile
turbine blade components during manufacture operations

Principle 38 Accelerated Oxidation

A. Replace common air with oxygen-enriched air
− Scuba diving with Nitrox or other non-air mixtures for extended
endurance
− Place asthmatic patients in an oxygen tent
− Nitrous oxide injection to provide power boost in high performance
engines
B. Replace enriched air with pure oxygen
− Cut at a higher temperature using an oxy-acetylene torch
− Treat wounds in a high-pressure oxygen environment to kill anaerobic
bacteria and aid healing
− Control oxidation reactions more effectively by reacting in pure oxygen
C. Expose air or oxygen to ionising radiation
− Positive ions formed by ionising air can be deflected by magnetic field in
order to (e.g.) reduce air resistance over an aerodynamic surface
− Irradiation of food to extend shelf life
− Use ionised air to destroy bacteria and sterilise food
D. Use ionised oxygen
− Speed up chemical reactions by ionising the gas before use
− Separate oxygen from a mixed gas by ionising the oxygen
E. Replace ozonised (or ionised) oxygen with ozone
− Oxidisation of metals in bleaching solutions to reduce cost relative to hydrogen peroxide
− Use ozone to destroy micro-organisms and toxins in corn
− Ozone dissolved in water removes organic contaminants from ship hulls

Principle 39 Inert Atmosphere

A. Replace a normal environment with an inert one
− Prevent degradation of a hot metal filament by using an argon
atmosphere
− MIG/TIG welding
− Electron beam welding conducted in a vacuum
− Vacuum packaging
− Foam to separate fire from oxygen in the air
B. Add neutral parts or inert additives to an object
− Naval aviation fuel contains additives to alter flashpoint
− Add fire retardant elements to titanium to reduce the possibility of titanium
fire
− Add foam to absorb sound vibrations – e.g. hi-fi speakers

Principle 40 Composite Materials

A. Change from uniform to composite (multiple) materials
− Aircraft structures where low weight and high strength are required
− Composites in golf club shaft
− Concrete aggregate
− Glass-reinforced plastic
− Fibre-reinforced ceramics
− Hard/soft / hard multi-layer coatings to improve erosion properties

12 Innovation principles for business and management

Pavel Livotov, Vladimir Petrov

TRIZ Innovation Technology. Product Development and Inventive Problem Solving.
Handbook / Pavel Livotov, Vladimir Petrov. Berlin: TriS Europe GmbH, 2010-2014, 284 pages.

The 12 double principles for Business and Management assist the user in resolving organisational contradictions and conflicts. They broaden the individual experiences and intuition of the manager and in addition help them to quickly formulate several different approaches to difficult situations.
Each principle represents two contradictory lines of action, which have to be taken into
consideration when searching for solutions. There is no recommendation as to which
action is the more suitable. The user is thus stimulated to think in a dialectic and
creative way.
1. Combination – Separation
2. Symmetry – Asymmetry
3. Homogeneity – Diversity
4. Expansion – Reduction
5. Mobility – Immovability
6. Consumption – Regeneration
7. Standardisation – Specialisation
8. Action-Reaction
9. Continuous– Interrupted action
10. Partial action – Excessive action
11. Direct action – Indirect action
12. Preliminary action – counteraction

Example
In companies quite often problems arise due to difficulties in communication. As an
example, the communication lack between a highly technically competent and thus
important individual and the rest of the staff can be used. The resulting personal
conflicts then have a negative effect on productivity and the working climate.
Here are some suggestions using the principles as to how to defuse the problem:

Principle 1. Combination – Separation:
• «Isolate» the person for the staff to avoid direct contact and organize a central
counsellor.
• Arrange for the «difficult» person to work at home or to have flexitime.
• Set up a database or an Expert System to make the expertise of the person
available to others.
Principle 2. Symmetry – Asymmetry:
• Reduce asymmetry in company expertise; internally train or hire several experts.
Principle 3. Homogeneity – Diversity:
• Encourage psychological homogeneity and raise the tolerance threshold of the
colleagues.
Principle 4. Expansion – Reduction
• Reduce the individual’s direct involvement with colleagues and in projects.
Principle 5. Mobility – Immovability:
• Reduce the individual’s sphere of movement within the company through
organizational means.
Principle 6. Consumption – Regeneration
Principle 7. Standardisation – Specialisation:
• Standardise company knowledge and working methods. Introduce knowledge
management.
• Use the unique (or specialist) knowledge of the individual to build up the
knowledge management system or have them organize this task.
Principle 8. Action – Reaction:
• Arrange a social and psychological guidance program for the individual.
Principle 9. Continuous action – Interrupted action:
• Only involve the individual in a consultative role and in certain phases of a project.
Principle 10. Partial action – Excessive action:
• Reduce the amount of time that the individual spends in projects.
Principle 11. Direct action – Indirect action:
• Provide a mediator or a social buffer for the individual in the team or in the
company.
Principle 12. Preliminary action – counteraction

 

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