Electronic Measurement Techniques for Coating/Paint Thickness Using STM32 Microcontroller

Abstract

Paint or coating thickness plays a critical role in product quality control, corrosion resistance, and cost optimization. This paper explores electronic methods for measuring coating thickness on various substrates using STM32 microcontrollers. The methods implemented include Magnetic Induction for ferrous materials, Eddy Current for non-ferrous substrates, and Ultrasonic Pulse-Echo for universal applications. Each sensor method is integrated with STM32 microcontroller-based data acquisition and control, with added support for Bluetooth transmission and Excel-compatible data logging. The goal is to provide a low-cost, modular, and portable alternative to conventional thickness gauges.

Introduction

This study presents a cost-effective system for measuring surface coating thickness using an STM32 microcontroller, addressing the need for affordable and customizable quality control tools in industries like aerospace and automotive.

Three measurement methods are implemented:

• Magnetic Induction: Uses a Hall effect sensor to measure non-conductive coatings on ferrous metals.

• Eddy Current: Measures conductive coatings on non-ferrous metals by detecting impedance changes.

• Ultrasonic Pulse-Echo: Employs ultrasonic pulses to measure coating thickness on any substrate, independent of material type.

The system integrates sensors, an STM32F103 microcontroller, Bluetooth communication, and optional displays for data acquisition and wireless transmission to PCs or smartphones. Implementation involves interrupt-based sensing and ADC polling, with software developed in STM32CubeIDE.

Experimental results show good accuracy for each method on different materials, while challenges include material limitations for magnetic and eddy current methods and the need for coupling in ultrasonic testing.

Conclusion

The proposed microcontroller-based system effectively measures coating thickness using three distinct techniques. Its low cost, modularity, and Bluetooth logging make it ideal for educational and industrial field applications. Future work includes Wi-Fi logging, Android app integration, and machine learning-based calibration.

References

[1] ISO 2178:2016 – Non-magnetic coatings on magnetic substrates – Magnetic method [2] ISO 2360:2017 – Non-conductive coatings on non-magnetic metal substrates – Eddy-current method [3] ASTM E797 – Standard Practice for Measuring Thickness by Ultrasonic Pulse-Echo Contact Method [4] M. Y. Demirci et al., \'Low-Cost Non-Destructive Thickness Measurement System Using Microcontroller,\' Sensors, 2021. [5] STM32CubeIDE and HAL Libraries – STMicroelectronics Documentation [6] A1302 Hall Effect Sensor Datasheet – Allegro Microsystems [7] HC-05 Bluetooth Module Datasheet – Wavesen Technology [8] Z. Tang et al., \'Development of Eddy Current Sensor for Coating Thickness Measurement,\' IEEE Transactions on Instrumentation and Measurement, 2019. [9] I. A. Ismail, \'Ultrasonic Thickness Measurement System Using Arduino and Piezoelectric Transducer,\' IJSE Research, 2020. [10] G. Srivastava, Electronic Measurements and Instrumentation, New Age International Publishers, 2009.

Copyright

Copyright © 2025 Vinod Yadav, Arvind kumar Mishra, Bharat Kathe. 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.