BX120-3AA High Precision Resistance Strain Gauge for Weight & Pressure Measurement

Specifications

• Model: BX120-3AA
• Nominal Resistance: 120 Ω (Ohms)
• Resistance Tolerance: ± 0.2%
• Gauge Factor (Sensitivity): ~2.0 to 2.2
• Strain Limit: 2.0%
• Base Material: Modified Phenolic / Polyimide (flexible backing)
• Grid Material: Constantan Foil
• Lead Wires: Pre-attached copper wire leads (standard length)

Applications

• Custom Load Cells: Build DIY weighing scales or digital force gauges.
• Structural Health Monitoring: Measure beam deflection or stress limits on 3D-printed parts and mechanical structures.
• Robotics & Automation: Implement force-sensing feedback in robotic arms or grippers.
• Aerospace & Automotive: Test material strain in chassis and airframes under physical loads.
• Medical Devices: High-precision weight and pressure detection beds or seats.

Unlock New Capabilities

• Past Projects: If you've previously used simple FSRs (Force Sensitive Resistors) for touch or pressure sensing, you know they are great for "is it pressed?" but terrible for "exactly how many grams is pressing it?"
• The Upgrade: Moving to the BX120-3AA unlocks high-precision, linear weight, and strain tracking. You go from basic pressure pads to building industrial-style weighing modules.
• Effort Level: Advanced. Strain gauges require precise surface preparation, specialized cyanoacrylate adhesives, and cannot be plugged directly into an Arduino. You must use an amplifier circuit.

Package Includes:

• 1 x BX120-3AA High Precision Resistance Strain Gauge (120 Ohm) for Weight & Pressure Measurement

Frequently Asked Questions (FAQ)

• What is the nominal resistance of the BX120-3AA?
  It has a nominal resting resistance of exactly 120 Ohms.
• Can I connect this directly to an Arduino Analog pin?
  No, the voltage change is too small. You must use an amplifier like the HX711.
• Do I need a Wheatstone bridge to use this?
  Yes, to convert the small resistance change into a measurable voltage, it must be part of a quarter, half, or full Wheatstone bridge.
• What does the "3AA" stand for?
  It generally denotes the grid dimensions (approx 3mm length) and the specific base/foil geometry of the gauge.
• How do I attach the strain gauge to my surface?
  The surface must be sanded, cleaned with a solvent, and the gauge must be glued completely flat using a specialized cyanoacrylate adhesive.
• Can I use regular super glue to mount it?
  Standard super glues can sometimes work for basic testing, but specialized strain gauge adhesives are required for accurate, creep-free results.
• What is the Gauge Factor?
  The Gauge Factor (GF) is typically around 2.0 to 2.2, which represents the ratio of fractional change in electrical resistance to the fractional change in length (strain).
• Is this temperature compensated?
  Yes, Constantan foil gauges are generally self-temperature compensated for standard structural materials like steel or aluminum.
• Can I cut or trim the backing of the gauge?
  It is not recommended, as you risk damaging the delicate foil grid or the pre-soldered lead connections.
• How many gauges do I need to make a load cell?
  You can use one (Quarter Bridge), two (Half Bridge), or four (Full Bridge). Four provides the highest accuracy and temperature stability.
• What is the maximum strain limit?
  The BX120-3AA can typically handle up to 2.0% strain before physical failure.
• Are the wires pre-soldered?
  Yes, this model typically comes with thin enameled or insulated copper wire leads pre-attached to the solder pads.