Stress Analysis Strain Gages Designed for Enhanced Humidity Protection

New stress analysis strain gage sensors with enhanced encapsulation offer improved protection from humidity

The new CHA Series humidity resistant strain gages are the latest addition to the company’s CEA Series strain gages, which are among the most popular of Micro-Measurements’ offering of strain gages. The CHA Series offers better humidity performance compared with the CEA family, making it the ideal choice for the most demanding applications such as humidity conditioned composite materials. Built to improve performance under ASTM-5229 “Standard Test Method Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials” test conditions, the CHA Series strain gages are currently available in several uniaxial, tee rosette, and rectangular rosette configurations.

CHA features and benefits are:

  • Cast polyimide backing for flexibility and toughness

  • Larger integral copper coated tabs for easier leadwire connection

  • Protective encapsulation film with enhanced moisture protection for the most demanding applications

  • Strain range: ±3% for all gage lengths, 5% for gage lengths of 0.250 inch or greater

  • Fatigue life: ±1500 microstrain for 10^6 cycles

  • Temperature range: –100° to +350°F (–75° to +175°C)

Further information about Micro-Measurements® CHA strain gages and technical support is available at


Strain gages are resistive sensors whose resistance is a function of applied strain (unit deformation). Stress is calculated from the strain information. Typically a strain gage is attached to a structure and when such a structure is deformed (tension, compression, shear), the resistive strands in the strain gage follow the structure deformation which causes an electrical resistance change. The resistance change is then expressed in units of strain or stress. Strain gages are used in transducers that convert force, pressure, tension, etc., into an electrical signal. They are also used for measuring strain in structures (stress analysis) such as airplanes, cars, machines, bridges and other structures. Performance specifications to consider when searching for strain gages include operating temperature, the state of the strain (including gradient, direction, magnitude, and time dependence), and the stability required by the application.

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Yuval Hernik

StrainBlog Editor in Chief