Penetrating the stratum corneum of human skin requires a minimum insertion force of 0.08 N per needle . To investigate the mechanical robustness, compression tests were conducted by applying a force of 50 N to evaluate their strength. The SEM image in Figure suggested that no apparent deformation was observed after penetration tests, confirming that each needle can withstand at least 2 N without fracture. Under the given force load, the deformation was manifested towards the side with a hollow hole without any fracture, which was consistent with the FEA result.