Microinjection Molding of Out-of-Plane Bistable Mechanisms

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Miniaturized bistable mechanisms are typically in-plane monolithic devices.
• Existing fabrication methods for such devices include microelectromechanical systems (MEMS) processes.
• Current designs often involve delicate elastic elements in metal or plastic.

Purpose of the Study:

• To present a novel fabrication technique for miniaturized out-of-plane compliant bistable mechanisms (OBMs).
• To utilize microinjection molding (MM) and assembly for creating these OBMs.
• To explore the potential of these mechanisms in architected materials.

Main Methods:

• Fabrication of out-of-plane V-beam structures using mold fabrication and MM of polyacetal resin (POM).
• Assembly of two single V-beam structures to form a double V-beam structure.
• Machining of a copper alloy mold insert and subsequent re-machining to account for shrinkage.

Main Results:

• Successfully molded V-beam structures exhibiting symmetrical melt filling.
• Demonstrated that a single molded structure shows monostable behavior.
• Assembled double V-beam devices exhibited clear bistability, confirmed by force-displacement curves.

Conclusions:

• The proposed technique enables the fabrication of out-of-plane compliant bistable mechanisms.
• The assembled double V-beam structure demonstrates bistability.
• This method offers potential for creating architected materials with periodic bistable mechanisms for functionalities like energy absorption and shape morphing.