Design and modeling of a force sensitive toothbrush by using a buckling truss structure

Abstract

Excessive force applied to teeth with a toothbrush during brushing may cause tooth erosion and gum recession. There have been many attempts by others to mitigate this effect with a force-sensitive toothbrush that can alert a user when excessive force is applied. However, many of the prior art solutions to this problem do not have a tactile response to alert the user when excessive force is applied. Further many prior art solutions are often bulky, have multiple components, and/or are not aesthetically pleasing or ergonomic. Some prior art buckling structures also often had thin hinge sections which are difficult to injection mold and act as failure points and the resulting broken structure can be dangerous. Prior art buckling toothbrush structures further had the problem of once they buckled, the structure was so substantially weakened, that continued application of force could cause the structure to plastically fail. A force-sensitive toothbrush incorporates a bistable truss into the neck of the toothbrush. The mechanism can alert a user to excessive brushing force by changing shape in response to brushing forces exceeding a predetermined threshold. The mechanism can also automatically return to its original state when the brushing forces are lowered back down below the predetermined level. The mechanism may include a force-sensitive region having an upper beam and a lower beam joined together to form a triangular truss, both grounded to the handle. This mechanism can advantageously be molded into an integral toothbrush body using an injection molding operation.