Multi-DoF Optothermal Microgripper for Micromanipulation Applications

Microgrippers have emerged in minimally invasive surgery and biomedical applications, enabling tasks such as gripping, micro-assembly, and cell manipulation. Realizing microgrippers with multiple degrees-of-freedom (DoFs) enables higher dexterity and multi-functionality. However, due to their small size and limited working space, the development of microgrippers with multi-DoF faces great challenges, requiring complex fabrication technologies and actuation mechanisms. Here we report a novel optothermally-actuated multi-DoF microgripper with multiple functionalities for micromanipulation. For this, three types of optothermal microactuators, namely bimaterial microjoints, chevron-shaped microactuators, and hot-cold arm microactuators are considered. The suitability of the chevron-shaped and hot-cold arm microactuators for mechanical pushing tasks is evaluated through modeling and simulation. Then, a 3-DoF microgripper incorporating two spiral bimaterial microjoints and one chevron-shaped microactuator is designed and fabricated. The selective and individual actuation of these microactuators is facilitated using a fiber bundle and a digital micromirror device. Finally, the performance and multi-functionality of the microgripper are demonstrated by performing multiple micromanipulation tasks of mechanical pushing and pick-and-release of microbeads. This work provides a proof of concept of an optothermal multi-DoF microgripper with multiple functionalities, opening the way for advanced dexterity at the microscale that is difficult to achieve using the current technology.