The present paper reports the development of a novel mechanical testing device that enables highly reliable mechanical tensile testing on individual micro-/nano-structures. The device features independent measurement of both force and displacement histories in the specimen with nanoNewton force and sub-picometer displacement resolutions, respectively. Moreover, the device is well suited for in-situ testing of micro-/nano- structures within a high resolution scanning electron microscope (SEM), which permits continuous high resolution imaging of the specimen during straining. The device comprises of two main parts: (a) a three-plate capacitive transducer that doubles up both as an actuator and a force sensor, and (b) a commercially available nano-manipulator that facilitates transportation and positioning of nanoscale structures with nano-precision. In order to conduct the mechanical tests, the two ends of the specimen are attached to the probe tips at the nanomanipulator and the transducer ends, using either electron-beam or ion-beam induced deposition (EBID/IBID). The working and capabilities of the testing device are illustrated by presenting results of nanomechanical tensile tests on electrospun polyaniline microwires. The engineering stress versus engineering strain curves exhibit two very distinct Young's moduli during the loading or the unloading segments of the applied displacement. Failure at the probe/sample weld junction occurred at ~ 67 MPa, suggesting that polyaniline microfibers exhibit a yield stress higher than most comparable bulk polymers.

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