Antibacterial Cold Plasma Device – 100 kHz · 40 kV

Variable High-Voltage High-Frequency System with Embedded Real-Time Control
2021

Supervisor: Dr. Borhan Beigzadeh – Head of Biomechatronics and Cognitive Engineering Lab (BACE), Iran University of Science and Technology
Lead Designer: A. Bagheri (B.Sc. Mechanical Engineering & Computer Engineering)

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🔬 Project Overview

A fully custom-designed cold atmospheric plasma device capable of delivering high-frequency (≈100 kHz) and high-voltage (up to 40 kV) output for antibacterial and experimental applications.

The system integrates power electronics, embedded control, sensing, and safety mechanisms into a single platform, fully designed, built, and tested from scratch.

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⚡ System Highlights

• Variable output: ~100 kHz / up to 40 kV
• Full custom power chain:
  • Function generator
  • Pre-driver stage
  • MOSFET full-bridge
  • Ferrite transformer
  • High-voltage output stage
• Embedded real-time monitoring:
  • Temperature (MOSFETs & transformer)
  • Frequency & duty-cycle feedback
  • Arc and abnormal condition detection
• Safety-first architecture:
  • Isolated feedback paths
  • Over-temperature protection
  • Automatic shutdown & restart logic
• Fully custom hardware:
  • PCB design (Altium)
  • Transformer winding
  • Assembly & testing

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🧠 Embedded Control System (Arduino Nano / ATmega328P)

The control unit is implemented using an Arduino Nano (ATmega328P) and demonstrates a modular embedded C-style architecture using the Arduino C++ framework.

Key Responsibilities

• Startup UI (OLED): "Cold Plasma"
• Real-time display:
  • Frequency (Hz)
  • Duty cycle (%)
  • Temperature (°C)
• Thermal management:
  • PWM fan control based on temperature
• State machine control:
  • Adjusting → Running → Overheat → Restart
• Stopwatch timing (using micros()) during operation phase
• Safety signaling:
  • Buzzer + LED warning before critical conditions
• Relay control:
  • Normally-closed relay for protection and system control
• Overheat handling:
  • Forced cooling
  • Controlled restart behavior

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🧩 Firmware Architecture (Public Demo)

This repository includes a public demo firmware designed to showcase code quality and system architecture without exposing sensitive implementation details.

File Structure

cold_plasma_controller_demo.ino # main entry point

config.h # pins, thresholds, timing constants

system_types.h # shared data structures & state definitions

sensors.h / sensors.cpp # measurement layer

control.h / control.cpp # state machine & control logic

display_ui.h / display_ui.cpp # OLED interface

Design Approach

• Modular layered architecture
• Clear separation of:
  • sensing
  • control logic
  • hardware outputs
  • user interface
• State-machine driven system behavior
• Non-blocking timing using millis() / micros()

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⚠️ Note on Public Firmware

This demo firmware intentionally:

• Uses placeholder calibration values
• Simplifies measurement and protection logic
• Omits hardware-specific tuning and proprietary algorithms

Its purpose is to demonstrate:

Code structure, embedded design thinking, and system-level architecture

—not to replicate the full production system.

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📊 System Block Diagram

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🖼️ Hardware Gallery

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🛠️ Technical Domains

• High-frequency high-voltage power electronics
• Ferrite transformer design & winding
• Full-bridge MOSFET drivers with dead-time control
• Embedded firmware design (ATmega328P)
• Real-time monitoring and protection systems
• PCB design (Altium Designer)
• EMI & safety considerations

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👤 Author

A. Bagheri
B.Sc. Mechanical Engineering & Computer Engineering – IUST (2021)

GitHub: https://github.com/aibgr
LinkedIn: https://www.linkedin.com/in/aibgr

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⭐ Support

If you find this project interesting or useful, consider giving it a star.

Schematics and full firmware may be shared under collaboration or agreement.

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One of my earliest full-stack hardware projects — still one of my favorites!