Printed circuit MEMS fabrication is a sequence of micromachining and lamination operations. It begins with laser cutting complex patterns into thin layers of structural materials and adhesive films. The layers are stacked and aligned using precision pins. Heat and pressure bonds the layers together into a flat laminate. These laminates can be micromachined again, and combining a variety of materials creates a mechanical structure with rigid beams and flexible joints.
Mobee has five layers of carbon fiber for rigid components, two plastic layers for flexible joints, two brass layers for locking, one layer of titanium to mimic insect wings, two piezoelectric ceramic inserts for actuation and eight layers of adhesive bond. Mobee is fabricated as two parts – the machine components and a surrounding mechanism called an assembly scaffold. The scaffold links 22 origami folds and pops them up in a single motion. The robotic bee is then released by laser cutting all connections between the scaffold and the device itself.
Mobee is powered when a voltage signal is applied to the actuator. The tip moves approximately half a millimeter at 100 to 200 times per second. A transmission made from rigid carbon fiber beams and flexible polymide film joints converts this half-millimeter motion into a 120-degree wing stroke, causing the wingtips to move about 3 centimeters.
Sreetharan started Vibrant Research to explore commercial opportunities for MEMS that extend beyond micro-robotics. He views printed circuit MEMS fabrication as a versatile process for creating machines at the millimeter scale. “It can embed electronics, incorporate high-performance materials and subcomponents, and be scaled into mass production.”