»Strain gauges

Monitor the deformations of structures and machines using a strain gauge

Do you need to find out how structures, machines or mechanical parts are stressed? Contact VTS Zlín s.r.o. We offer semiconductor and metal strain gauges. According to the request, we will manufacture tensometric sensors for measuring force, weight, the action of pressure or torque, etc.

Principle and production of strain gauges

The essence of a semiconductor strain gauge consists in a significant change in its resistance with mechanical deformation. The effect of mechanical stress in a certain crystallographic axis of a semiconductor single crystal or in the diffusion layer of a semiconductor causes a change in electrical conductivity. The change in resistance depends on the type of semiconductor and the concentration of impurities.

Properties and use of strain gauges

Compared to previous generations of wire and foil strain gauges, semiconductor strain gauges have:

  • 60x higher deformation sensitivity allows measurements without amplifiers with common ohmmeters, voltmeters and oscilloscopes
  • A 60x higher threshold sensitivity makes it possible to measure the deformation of metals starting from a millionth of a millimeter per length meter
  • high sensitivity makes it possible to measure very small forces or accelerations in the nominal range
  • wide measurement frequency range from static values up to several kilohertz
  • small dimensions allow to create small and light sensors
  • the results of the stress analysis of the parts that we can subject to controlled heating are absolutely reliable
  • silicon deforms without measurable hysteresis up to 300 ºC
  • silicon gold strain gauges have excellent corrosion resistance
  • the disadvantage is the deviation from the linear characteristic and significant temperature dependence, which, however, is usually compensated

Semiconductor strain gauges are almost exclusively used in sensors of mechanical quantities both in the most demanding test equipment and for controlling and securing machines. These sensors will give all mechanisms the ability to respond sensitively to mechanical stimuli, and we usually get them very cheaply.

When installed directly on parts of machines, they can be used for experimental analysis, which determines the magnitudes and courses of operational stresses of machine and building structures, reveals weak and oversized areas of structures, thereby making it possible to exclude malfunctions and save material.

They are mainly used in traction, pressure, torque, bending, acceleration, weighing and many other individual devices.

Economic benefits

  • using the original technology, we achieve top quality strain gauges comparable to foreign production
  • the purchase price of single-purpose sensors with “semiconductors” from VTS Zlín is comparable to universal sensors with metal strain gauges
  • in the design and manufacture of sensors, we use proven experience in the aviation industry
  • we install strain gauges on measuring members and machine parts with special strain gauge adhesives for overhead costs

Calibration and service life of strain gauges

The strain gauges are tested according to the procedures prescribed by the strict American standard NAS 942. Each manufactured strain gauge is glued to a test beam and subjected to a gradual deformation in the range of ±2.5×10 -3 [m/m], while the electrical resistance is measured.


Layout and dimensions

The strain gauge consists of a strip of monocrystalline silicon with attached gold leads with a diameter of 0.07 mm. The silicon strip is self-supporting, does not require a support pad, which is necessary for wire and foil strain gauges, and is electrically isolated from the measured object with a layer of hardened glue of around 0.03 mm, created before sticking the strain gauge.

Code designation and dimensions

Tolerance of strain gauges

At present, we have these types of strain gauges in stock: Type „Positive“, length 1.5mm, 3mm and 6mm, with gauge factor C1 = 120 – 150 and with electrical resistance 120 , 350 and 1000 Ohm. Of course, we are able to produce strain gauges with parameters according to customer’s requirements.

We deliver semicoductor strain gauges in two sorts of tolerance at pack, specified by assurance of their tolerance characteristics. For dynamic measurement and stable temperatures are suitable strain gauges marked as N-sort. For static measurements, sensors and strain gauges for temperature fluctuation are suitable ones marked as T-sort.


Use in practice