Caterpillar Robot Flips Out In Style: The Structure-Function Relationship in Biomimetic Inventions
Biomimicry is a conscious look to nature for novel design solutions. In the video above, robotics designers looked to the fascinating speed at which a Crambidae caterpillar reacts to danger in order to build a faster robotic response. The bot they created has a 10cm-long silicon body with embedded shape memory alloy coils, allowing it to roll like a freaked out caterpillar with an angular velocity of 300 rpm. The design is one species in the new genre of flexible and agile robots that is poised to replace the clunky R2-D2 style that has been the industry standard.
Biomimetics is not limited to robotics. People have been looking to nature for inspiration throughout history: Velcro was inspired by the microscopic hooks on the burs of a burdock tree that stuck to the clothing of an engineer hiking through the Alps. New clay roofing tiles are inspired by the leaves of the lotus plant, which stay dirt-free even when immersed in a typically muddy habitat. And the list goes on.
When seeking to patent a biomimetic invention, it is tempting to use functional language to claim the invention (Rolls like a caterpillar! Stays dirt-free like a lotus plant!). A functional limitation is an attempt to define something by what it does, rather than by what it is. Functional language is permitted and is often used to define a particular capability or purpose served by the recited element, ingredient, or step in the claim.
But when the function is borrowed from nature, relying on what the invention does (as opposed to what the invention is) falls short of accurately claiming the invention. In an apparatus claim, for example, features that are recited functionally do not distinguish the prior art; only the structure of the claimed invention is considered in relation to the prior art. Unless the “rolls like a caterpillar” function is coupled with the structure that performs the function, the claim is missing the critical “this is what the invention is” piece of the puzzle.
In February, the USPTO issued supplementary guidelines concerning the requirement of definiteness from 35 U.S.C. §112 (second paragraph), and the interpretation of means-plus-function language based on the sixth paragraph of the same section. When considering the ambiguity of functional language under the second paragraph, the guidelines set forth a three part test: first, whether there is a clear-cut indication of the scope of the subject matter covered by the claim; second, whether the language sets forth well-defined boundaries of the invention or only states a problem to be solved or a result obtained; and third, whether one of ordinary skill in the art would know from the claim terms what structure or steps are encompassed by the claim. ”Rolls like a caterpillar” is a result obtained and needs to be combined with the structure of the bot that does the rolling in order to meet the definiteness requirement of 35 U.S.C. §112.
Under the sixth paragraph of §112, pure functional language is permitted in a claim that utilizes the terms, “means for” or “step for,” and does not include further structural limitations. In means-plus-function claims, the written description must contain corresponding structure, material, or acts that perform the claimed function. Thus, the sixth paragraph of §112 still requires description of the structure of the invention (albeit in the written description instead of the claims). Ultimately, the bot is not adequately described by the function that it performs.
Biomimetic inventions copy the function of nature into a man-made design solution. When claiming these inventions, functional language is useful to quickly relate what the invention accomplishes; however, functional language by itself is not enough to describe what the invention actually is.