A 3D printed tensile testing system for micro-scale specimens

Mechanical property characterization of micro-scale material systems, such as free-standing films or small diameter wires (<20 µm), often requires expensive, specialized test systems. Conventional tensile test systems are usually designed for millimeter scale specimens with the force sensing capability of >1N while microdevice-based testers are intended for micro-/nano-scale specimens operating within a much smaller force range of <10 mN. This disparity leaves a technology gap in reliable and cost-effective characterization methods for specimens at the intermediate scale. In this research, we introduce the cost-effective and all-in-one tensile testing system with a built-in force sensor, self-aligning mechanisms, and loading frames. Owing to the advantages of 3D printing technologies, the ranges of force measurement (0.001-1 N) and displacement (up to tens of millimeters) of our 3D printed tensile tester can be readily tailored to suit specific material dimension and types. We have conducted a finite element simulation to identify the potential sources of the measurement error during tensile testing and addressed the dominant errors by simply modifying the dimension/design of the loading frames. As a proof-of-concept demonstration, we have characterized fine copper (Cu) wires with 10-25 µm diameters by the 3D printed tensile tester and confirmed that the measured mechanical properties match with the known values of bulk Cu. Our work shows that the proposed 3D printed tensile testing system offers a cost-efficient and easily accessible testing method for accurate mechanical characterization of specimens with cross-sectional dimensions of the order of tens of micrometers.