Tiniest Universal Material Testing System

Photo: Woman with a magnifying glass

In the world of nanotechnology where the mechanical characterization of materials and structures takes place on the scale of atoms and molecules, the existing material testing systems are useless. The development of a universal nanoscale material testing system (n-MTS) has been a major challenge within the scientific community.

Now the machine developed by Northwestern University researchers fits in tiny spaces as required by in situ transmission electron microscopy (TEM) and it successfully characterized the mechanical properties of nanowires and carbon nanotubes.

The n-MTS developed by Horacio D. Espinosa, professor of mechanical engineering, consists of an actuator and a load sensor fabricated by means of micro technology. The load sensor is based on differential capacitive sensing, which provides a load resolution of about 10 nano Newtons. This is the first nanoscale material testing system that provides continuous observation of specimen deformation and failure with sub-nanometer resolution while simultaneously measuring electronically the applied forces with nano-Newton resolution. The integration of electro-mechanical and thermo-mechanical components at the micro scale made the achievement possible.

The system capabilities were demonstrated by in situ electron microscopy testing of free-standing polysilicon films, metallic nanowires and carbon nanotubes (CNTs). Espinosa's team achieved the first real-time instrumented in situ transmission electron microscopy observation of CNTs failure under tensile loading.

The n-MTS can be potentially applied to characterize the mechanical, thermal and electro-mechanical properties not only of nanowires and nanotubes but also of a large number of organic materials, including DNA, proteins and nanofibers.

COMPAMED.de; Source: Northwestern University