Surprising Uses for Oobleck

Oobleck is a common name for a non-Newtonian fluid comprising cornstarch and water. Named after a substance humorously described in Dr. Seuss’s classic children’s story, Bartholomew and the Ooblek, the cornstarch and water concoction is frequently used in children’s science classes as a fun way to learn about fluid mechanics. You may have fond memories, yourself, of playing with oobleck as a youth. Oobleck behaves as a fluid when touched gently, but becomes hard as a solid when hit with great velocity. For example, a person could run across a swimming pool of oobleck without getting their feet wet. However, if a person stood still on the oobleck, then they would slowly sink.

Because oobleck is a children’s plaything and because of its simple recipe (cornstarch and water), one may be surprised to learn that inventors have attempted to patent serious industrial uses for the material. As an example, one current patent application, US 2015/0016885 (now abandoned), is for a system of filling potholes with bags non-Newtonian fluids, such as oobleck. The patent application notes that permanently fixing potholes must often be delayed due to economic and seasonal reasons. Thus, the application provides a system of temporarily fixing potholes by filling them with bags of oobleck (or other non-Newtonian fluids). When the bag is placed in the pothole, the oobleck has time to act like a fluid and fill the hole. However, when a car or truck runs over it, the oobleck acts as a solid, preventing damage to the vehicle. The oobleck is easily removed when necessary, and is environmentally benign. The application suggests a mixture of two cups of water to 1 pound of cornstarch, but notes that other concentrations are suitable “as will be appreciated by one of ordinary skill in the art.”

One oobleck-using invention for which Honda Motor Company received a patent in 2011 is US Patent #7,959,201, which discloses a gear damper comprising oobleck. Gear dampers are often used in automobile interior applications to control the moving speed of components such as pocket lids, trays, and glove boxes. The dampers use a fluid to slow the speed at which a particular gear can move. The patent addresses a situation in which a car is involved in a crash with high g-force, wherein geared components may open themselves due to the forces present during the crash. Using a fluid such as oobleck ensures that the devices open properly when used normally, but resist opening when a great force is involved. After all, it is bad enough being in an accident; the last thing you need is to have your ashtray or glove compartment open and spill all over the place. And does this invention really use oobleck? Yes, claim 8 of the patent states “The gear damper of claim 1 wherein the damper fluid comprises: cornstarch; and, water.”

 Oobleck even has military applications. In 2013, Lockheed Martin was issued US Patent 8,448,559 for a “Vehicle Hull including Apparatus for Inhibiting Effects of an Explosive Blast.” Noting “modern combat theaters require new operational doctrines to counter unsymmetrical and unpredictable threats,” Lockheed has developed a vehicle hull technology comprising a non-Newtonian fluid that is lightweight, low-cost, and can be retrofitted to existing vehicles, providing them means for inhibiting effects of explosive blasts. Claim 21 of the patent states “The vehicle hull of claim 5, wherein the shear thickening fluid comprises: one of a dispersion of cornstarch in water, a dispersion of a clay in water, a dispersion of titanium dioxide in water, and a dispersion of silica in water.”

However, in my opinion, the best invention using a non-Newtonian fluid may be US Patent #7,942,603, for a “Speed Sensitive Traffic Control Device.” This invention is a speed bump consisting of a shell body containing a non-Newtonian fluid. When a car is moving at the correct speed, the speed bump squashes and allows the car to pass without obstruction. However, when a car is moving too fast, the non-Newtonian fluid acts as a solid and hinders the car’s movement. Although the patent does not describe oobleck per se as the fluid.  Rather it  suggests a mix of silica and polyethylene glycol, and it is certainly a clever enough use of a non-Newtonian fluid to warrant mention.

Now, the next question: Who is going to be the first to patent an industrial use for flubber?