Weight Measurement using Strain Gauge and Arduino

Abstract

This paper presents a cost-effective and accurate weight measurement system utilizing a strain gauge, Wheatstone bridge configuration, and an Arduino microcontroller. The strain gauge, attached to a bending beam, detects the deformation caused by applied weight, which is then translated into a change in resistance. This resistance variation is converted into a voltage signal using a Wheatstone bridge circuit and amplified to a level suitable for the Arduino’s analog input. The Arduino microcontroller processes the analog signal, applies calibration factors, and displays the weight measurement on a connected display. The system’s performance is evaluated through experimental testing, demonstrating its reliability and suitability for various weight measurement applications requiring affordability and ease of implementation.

Introduction

1. Origin of the Strain Gauge

• Invented in 1938 independently by:

  • Edward E. Simmons (Caltech) – to measure stress in metals.

  • Arthur C. Ruge (MIT) – for earthquake research in water tanks.

• Their invention laid the foundation for modern electronic weight measurement.

• Practical weight applications evolved over time with contributions from many.

2. Strain Gauge Fundamentals

• A strain gauge measures deformation in a material.

• Key principle: Resistance changes as a material stretches or compresses.

• Core formula:
  R=ρLAR = \rho \frac{L}{A}R=ρAL?

• Gauge Factor (GF) quantifies sensitivity:
  GF=ΔR/R?GF = \frac{\Delta R / R}{\epsilon}GF=?ΔR/R?

• A Wheatstone bridge is used to detect tiny resistance changes accurately.

• Poisson’s Ratio and piezoresistive effect also impact measurement.

3. Project Overview

• Goal: Build a low-cost, accurate, digital weight measurement system.

• Tools used:

  • Strain gauge

  • HX711 amplifier (ADC)

  • Arduino microcontroller

• Applications:

  • Digital scales

  • Force sensors for robotics

  • Industrial material monitoring

• Highlights the integration of classic sensor tech with modern microcontrollers.

4. System Concept and Design

• A force applied to the strain gauge deforms it → resistance changes → voltage signal (via Wheatstone bridge).

• HX711 amplifies this signal and converts it to digital.

• Arduino reads the signal, processes it, and displays weight.

5. Key Components

• Strain Gauge: Core sensor for force detection.

• HX711: Amplifier + 24-bit ADC for accurate digital readings.

• Arduino: Processes and outputs weight data.

• Load Cell: Mechanical structure with pre-bonded strain gauges.

• Calibration Weights: For accurate system tuning.

• Power Supply, Connecting Wires, Breadboard, Arduino IDE.

6. Circuit Connections

• Load Cell → HX711 → Arduino

  • Red → E+

  • Black → E-

  • White → A-

  • Green → A+

  • HX711 VCC → Arduino 5V

  • HX711 GND → Arduino GND

  • DT (data) → Arduino pin (e.g., D2)

  • SCK (clock) → Arduino pin (e.g., D3)

7. Calibration Process

• Upload code to Arduino.

• Open Serial Monitor.

• Tare (zero) the scale.

• Place known weights and read output.

• Calculate calibration factor:

  Calibration factor=ReadingKnown weight\text{Calibration factor} = \frac{\text{Reading}}{\text{Known weight}}Calibration factor=Known weightReading?

• Use multiple weights for better accuracy.

8. Key Considerations

• Stable Power Supply

• Shielded Wires (to reduce noise)

• Temperature Compensation (to correct environmental effects)

• Secure Mounting (for repeatable results)

• Linearity and Resolution (check across range)

Conclusion

This project successfully demonstrates the feasibility and effectiveness of using a strain gauge, Wheatstone bridge, and Arduino microcontroller to create a costefficient and accurate weight measurement system. The experimental results confirm the system’s high linearity and accuracy within [Specific percentage or range of error], proving its reliability for practical applications. Furthermore, the simplicity of the design and the ease of implementation highlight its potential for use in diverse scenarios requiring affordable and customizable weight measurement solutions, such as in educational settings, DIY projects, and small-scale industrial applications.The integration of readily available components and the open-source nature of the Arduino platform contribute to the system’s accessibility, allowing for further development and adaptation to specific user needs. Ki

References

Sensors and Transducers by D. Patranabis Electronic Devices and Circuit Theory by Robert Boylestad and Louis Nashelsky Programming Arduino: Getting Started with Sketches by Simon Monk Measurement Systems: Application and Design by Ernest O. Doebelin Getting Started with Arduino by Massimo Banzi and Michael Shiloh

Copyright

Copyright © 2025 Sanskruti U. Deshpande , Pooja R. Jadhav , Sanjana V. Jogangari , Shreya C. Tungenwar , Prof. O. S. Chavan . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.