Advanced manufacturing processes are opening up entirely new design spaces for microactuators. We first combined microscale 3D printing using two-photon polymerization with physical vapor deposition of metal (e.g., Al, Au, and NiTi). This method enables microscale actuators with complex 3D geometries that are extremely difficult to achieve with conventional microfabrication techniques.

In parallel, we explored metal deposition over functional polymers like liquid crystal elastomers to develop soft actuators at small scales. By leveraging the small size of the actuator, we significantly enhanced the bandwidth of the thermal actuators, making these actuators suitable for high-speed and high-force wearable haptic applications.

Flexible printed circuit boards (FPCBs) have significnat potential for microrobotic applications due to their advantages of being lightweight, flexible, and easily integrated with electronic components. In this study, we directly fabricated 3D electrostatic actuators on top of FPCBs and demonstrated two microrobotic applications. Our 4 mg crawling robot is one of the lightest legged microrobots that does not require external fields such as magnetic fields for actuation. We also created a micromirror array that integrates microcontrollers and MOSFETs, enabling individual control of 3D printed mirrors on a flexible substrate.

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Soft robots can easily conform to the environment and safely interact with the surroundings. Especially, soft growing robots utilize tip-eversion for frictionless locomotion, enabling the robot to navigate tortuous and complex environments (e.g., pipe, underground, and inside human body). Here, we developed a fabrication method to create millimeter-scale soft growing robots by heat-bonding thermoplastic films. We are also investigating methods to functionalize the skin of the robot to integrate steering, stiffening, and retraction mechanisms.

Origami-inspired mechanisms use rigid facets and flexible fold lines to achieve large changes in both shape and stiffness. Flexure-based joints, formed by these fold lines, eliminate friction and backlash, which becomes more significant at smaller scales. By laser machining several films in 2D, and then folding them into 3D shapes, we can easily create complex, small-scale mechanisms.