Karma Foil Strain Gauges
(Karma Alloy)
Karma foil strain gauges are precision foil strain gauges manufactured using Karma alloy foil instead of the more common Constantan foil. Constantan is a popular general-purpose choice, but many engineers specify Karma foil when they need improved performance in temperature-varying environments or demanding test conditions. At MFL Strain Gauges (based in N.Ireland) we manufacture multiple gauge styles in Karma foil, including:
Linear strain gauges
Linear diaphragm strain gauges
Shear strain gauges
Circular strain gauges
Dual strain gauges
Full bridge strain gauges
Rosette strain gauges
If you’re designing for stability, accuracy, and repeatability under changing temperature conditions, Karma foil can be the right material choice.
What is Karma foil & how is it different to Constantan?
Karma is a strain gauge foil alloy used to produce highly stable grids, particularly when temperature effects must be controlled. Constantan is widely used for general strain measurement because it’s versatile and easy to work with, but Karma is often chosen when applications demand better thermal behaviour and long-term stability.
Why choose Karma foil over Constantan foil?
Key advantages of Karma foil strain gauges
Better performance in temperature varying applications
Karma foil is commonly selected where temperature changes would otherwise introduce measurement drift or reduce accuracy.
High stability for demanding measurement
Karma gauges are often used in precision sensing and long duration tests where repeatability and stability are critical.
Suitable for higher performance bridge configurations
Karma foil is frequently used in full bridge networks and other configurations designed for stable, high-quality signals.
Disadvantages and trade-offs of Karma foil
More difficult to solder leads and wires
Karma foil is generally more challenging to solder than Constantan. This can require tighter process control, suitable flux/solder choices, and careful technique to avoid damaging the gauge or creating unreliable joints.
More Expensive
Because of handling and joining considerations, Karma foil is often used when its thermal/stability advantages are needed not simply as a default replacement for Constantan.
Karma foil gauge types available from MFL
We can manufacture the following Karma foil strain gauge styles:
Linear (single-axis strain measurement)
Linear Diaphragm (pressure diaphragm / transducer applications)
Shear (torsion and in-plane shear strain)
Circular (hoop strain and strain around holes/bolt circles)
Dual (two grids on one carrier for bending/compensation/redundancy)
Full Bridge (Wheatstone full bridge networks for high output and stability)
Rosette (multi-direction strain for principal strain/stress analysis)
Options and customisation with MFL Karma Foil Gauges
MFL Karma foil gauges are available with:
A range of grid sizes
Multiple resistance options
Different lead styles
Optional encapsulation when environmental or handling protection is required
Pre-tinned tabs for easier customer soldering
Typical applications for Karma foil strain gauges
1) Temperature varying test environments
When tests run through changing ambient temperatures (or components warm during operation), Karma foil gauges are often chosen for improved measurement stability.
2) Long-duration monitoring and endurance testing
For fatigue rigs, long term validation testing, and monitoring where drift control matters, Karma foil can support more repeatable results over time.
3) Precision transducers and bridge based sensors
Karma foil is commonly specified in sensing elements where bridge performance and stability are critical, including:
Load and force transducers (with appropriate bridge arrangements)
Pressure transducers (including diaphragm based designs)
Torque and torsion measurement setups
4) Aerospace, automotive, and advanced R&D
In high performance development work, Karma foil may be selected when the strain measurement needs to remain stable despite thermal changes and complex loading.
5) Multi-grid and analytical measurements
For rosettes, dual gauges, and full-bridge configurations where matching and stability matter, Karma foil can be a strong choice when the application demands it.
Why choose MFL Strain Gauges for Karma foil?
As a N.Ireland-based foil strain gauge manufacturer, MFL provides:
Karma foil gauges across multiple patterns (linear, shear, circular, dual, full bridge, rosette, diaphragm)
Options for grid size, resistance, lead style, and encapsulation with the option for Pre-tinned tabs
Support selecting the right foil type (Karma vs Constantan) for your application and environment
Karma foil strain gauge FAQs
What is the main reason to choose Karma foil over Constantan?
Karma foil is commonly chosen for better stability in temperature varying conditions and demanding measurement environments where drift control is important.
Is Karma foil harder to solder than Constantan?
Yes—Karma foil is generally more difficult to solder wires and leads onto than Constantan, so careful process control and appropriate technique are important. MFL offer pre-tinning of Karma tabs.
Do you offer Karma foil in different gauge types?
Yes—MFL manufactures Linear, Linear Diaphragm, Shear, Circular, Dual, Full Bridge, and Rosette strain gauges using Karma foil.
Can you supply different sizes, resistance values, and lead styles?
Yes—MFL offers a range of grid sizes, resistance options, and lead styles, with encapsulation available when required.
How do I know whether I need Karma foil or Constantan foil?
If your application involves temperature variation, long-duration measurement, or demands high stability, Karma may be a better choice. Karma should not be a direct replacement for Constantan gauges, unless absolutely required. The cost might outweigh the benefit. Share your material, temperature range, strain level, and measurement setup, and we can recommend the best foil option.