ST350 Strain Transducer

ST350 Strain Transducer

The ST350 Strain Transducer has been designed to quickly and accurately measure strain on a variety of structures in harsh field environments. This 350Ω full Wheatstone bridge strain transducer is very accurate, rugged, and waterproof.   

Providing roughly 3.5 times the output of a typical foil strain gage, these reusable sensors are ideal for measuring live-load strain on structures and can be installed within minutes in all weather conditions. Over 30 years of experience have proven these units to be the gold standard for accurate field measurements. 

We have a full suite of accessories for the ST350 which allow you to measure strain on steel, concrete, reinforced concrete, fiber reinforced polymers, and timber.

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Features – ST350 Strain Transducer

  • Cost-effective  
  • Installs in 5 minutes or less  
  • Reusable, lasts for >10 years  
  • Waterproof to 20ft (6 m)  
  • Industrial cable, custom lengths  
  • Standard millivolt output  
  • NIST-traceable calibration  


  • Steel
  • Pre-stress/post-tension concrete
  • Reinforced concrete
  • Timber
  • Fiber Reinforced Polymer (FRP)
  • Live-Load testing & monitoring
  • Laboratory testing
  • Fatigue monitoring
  • Tension rod forces


SPECIFICATIONS – ST350 Strain Transducer

CIRCUIT Full Wheatstone bridge with 4 active 350Ω strain gages
EXCITATION VOLTAGE +1.0 to +10.0 Vdc
OUTPUT mV level, ratiometric to Excitation Voltage
STRAIN RANGE  ±4,000 µε (Calibrated to ±2,000 µε)
EFFECTIVE GAGE LENGTH 3.0 in (76.2 mm) [Gage Extensions available for R/C structures]
HOUSING Machined 6061 Aluminum Alloy
CORROSION PROTECTION Hard Anodized Clear (MIL-A-8625 Type III)
WEATHER PROTECTION Designed to exceed IP67
Optional 100 ft (30 m), waterproofing available
TEMPERATURE RATING2 -58° to +176 °F (-50° to +80 °C)


1 Accuracy defined at the calibrated ±2,000 µε range.
2 Temperature limit based on instrumentation cable operating temperatures, call BDI for wide temperature range cable options.


Options & Accessories – ST350 Strain transducer