A novel method for in situ uniaxial tests at the micro/nano scalepart I: Theory

Wonmo Kang, M. Taher A. Saif

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


A novel MEMS-based uniaxial testing apparatus and a specimen design are presented for measuring the mechanical response of material samples in situ in scanning electron microscope (SEM). The stage adopts an assembly approach, where specimens are fabricated independently, allowing testing of a variety of materials. The assembly approach, however, involves intrinsic challenges in achieving pure uniaxial loading at the micro/nanoscale due to off-axis loading (misalignment) errors. The effect of misalignment in stress evaluation increases with decreasing size scale of the samplean issue that has received limited attention in the literature. Here, the source of intrinsic misalignment and its influence on the stress nonuniformity are explored analytically and numerically. This paper reveals substantial bending of the microspecimen due to small and often unavoidable off-axis loading. The proposed stage and the specimen ensure uniaxial loading by introducing hingelike self-aligning mechanisms both in the stage as well as in the specimen. The analysis offers the parameter space to design and optimize uniaxial tests at the micro/nanoscale.

Original languageEnglish (US)
Article number5597908
Pages (from-to)1309-1321
Number of pages13
JournalJournal of Microelectromechanical Systems
Issue number6
StatePublished - Dec 2010
Externally publishedYes


  • Electron microscopy
  • materials testing
  • microassembly
  • microelectromechanical devices
  • strain measurement
  • stress measurement

ASJC Scopus subject areas

  • Mechanical Engineering
  • Electrical and Electronic Engineering


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