Optimizing the load capacity of a compliant-mechanism-based microplate gripper for biomedical lab automation

Objectives: Laboratory automation enhances repeatability and throughput in scientific and industrial applications. An important aspect of automation is transportation of standardized components, such as microplates (MPs). Previously, we developed the compliant-mechanism-based gripper ("CrocoGrip"), enabling secure and contamination-free MP transport. However, we have yet to optimize the gripping jaws to increase the gripper's maximum load capacity (LC). In this paper, we optimize the design and surface of CrocoGrip's jaws to optimize its LC. CrocoGrip works like a torsion spring, so its opening width, which defines the CrocoGrip's deformation, its jaw arm length, and the jaw's surface material affect its LC. Methods: We tested the LC of six different jaw materials at different opening widths. The best-performing jaw surface was further evaluated at a second jaw arm length. Results: Jaws equipped with silicone inserts performed the best (LC=2.93 N). Aluminum with different surface smoothness performed the worst (0.68 N≤LC≤1.56 N). Decreasing the jaw arm length from 81 mm to 66 mm increased the LC of the silicone-insert jaws to 3.71 N. Conclusions: The improved LC allows the safe handling of MP (weight ≤127 g), enabling the use of the CrocoGrip for a broader range of tasks.