Project



Summary

The project aims to leverage the resources of the Fab Academy to advance doctoral research by developing an atmospheric pressure plasma reactor for disinfecting endoscopes. This involves designing the reactor using dielectric barrier discharge (DBD) technology and creating a high-voltage generator to power it. Atmospheric plasma, also known as cold plasma, operates at room temperature and can sterilize surfaces by disrupting bacterial defenses with reactive species like ions and UV photons. The project encompasses various components including the high-voltage generator, plasma reactor, measurement tools, and user interface, with a detailed plan for design, testing, and integration into the Fab Academy curriculum. The successful development and demonstration of the reactor highlight the practical applications of atmospheric plasma in medical sterilization, showcasing the potential for future enhancements and broader applications.

Below is the slide that summarizes the project, along with the one-minute video.

general draft

Introduction

General Idea

My project at the Fab Academy is all about harnessing its resources to advance my doctoral research. I’m diving into the world of atmospheric pressure plasma reactors, aiming to create a tool for disinfecting endoscopes. These reactors zap bacteria with atmospheric plasma, disrupting their defenses and making them harmless. I’ll be focusing on designing the reactor itself, using something called a dielectric barrier discharge (DBD), and crafting a high-voltage generator to power it up. By bringing this cutting-edge technology to the Fablab community, I hope to explore new applications and tackle practical challenges head-on.

The aim of the project is to design and develop an atmospheric plasma reactor and it’s high-voltage generator.

Atmospheric Plasma

Atmospheric plasma, often referred to as cold plasma, represents a captivating frontier in science and technology. Unlike traditional plasmas generated in high-temperature environments, atmospheric plasma operates at or near room temperature, making it suitable for a wide range of applications across various industries. At its core, atmospheric plasma consists of ionized gases containing a diverse array of reactive species, including ions, electrons, radicals, and UV photons. These reactive species endow atmospheric plasma with remarkable capabilities, ranging from surface cleaning and sterilization to material deposition and surface modification. By harnessing the unique properties of atmospheric plasma, researchers and engineers are unlocking innovative solutions to challenges in fields as diverse as healthcare, electronics, agriculture, and beyond.

Below is an illustration from Carles Corbella & al. showing, in the center, a diagram of the activity of such plasma and what it produces from a chemical point of view. On the left are various plasma reactor configurations, and on the right is a real picture of atmospheric plasma.

plasma scheme
From left to right : Different plasma reactor configurations ; scheme of plasma applications on surface ; testing Plasma Jet.

Some interesting reading


Draft

The project begins with a draft. This is created using a block diagram shown below to help visualize the various elements.

general draft

Each block can be described in more detail in the next section. A brief description of the blocks is given here :


Function Descriptions

1. HV Generator

This is the most complicated function. In fact, it requires a fairly advanced knowledge of power electronics, a field of electronics that focuses on energy transfer. Here, the idea is to start with a low-tension DC voltage generator (max 30V), which won’t need much power, so it’s a commercially available generator (my research lab has several, lucky me). An electronic circuit mainly composed of MOSFETs will transform this constant tension into an alternative one.Basically, the circuit will open one branch and then the other several thousand times per second. The result is an oscillating signal at the output. This is controlled by a microcontroller (an arduino, for example). Finally, there’s a transformer to switch from a low AC voltage to a (very) high AC voltage. In terms of current, we’re talking about milliamperes but yes, there’s a chance of electrocuting yourself to death, so you need to be extremely careful!

draft hv generator

2. Plasma Reactor

This function groups together all the elements required for atmospheric plasma. The main element is the dielectric barrier in which discharges are created. These discharges are known as plasma. To have a dielectric barrier, you need two electrodes, one powered by high voltage, and the other connected to earth. A dielectric medium is also required, and this role is played by a noble gas. In fact, these gases can easily be ionized at high voltage, allowing plasma discharges to propagate through them. A fairly common example of plasma in a noble gas is neon or xenon light.

draft plasma reactor

3. Measurement

This function consists, quite simply, of taking measurements of the various data needed to control the plasma reactor. Ideally, you’ll need :

4. User Interface

The user interface will :


Involvment into the FabAc’s Program

Here, I’ll summarize the direct links found between the project and the Fab Academy program.

Function Program Involvement
Hight
Voltage
Generator



Week Unit Description
2 CAD 3D modeling of the power supply
4 Electronics Production Manufacture (engrave) the pcb & solder components
6 Embedded programming Programming the arduino for use with generators and feedback control
8 Electronics Design Design of power electronics & arduino integration & control electronics.
9 Output Device Interface screen
10 Machine Design Design covering the entire prototype
12 Input Device Interactive features (buttons, potentio, touchscreen, etc.)
15 Interface & Application Programming Programming control interface
Plasma
Reactor
2 CAD 3D modeling of the reactor
7 CNC Machining Manufacture of the various elements (e.g. milling of the hollow part through which the gas passes and the HT enters) & perhaps protective elements
10 Mechanical Design Design of the "high-voltage probe" and maybe an easy way to insert it into a tube
Measures &
Feedback Control
12 Input Device Sensors & other measurements (voltage, power)
15 Interface & Application Programming Program feedback based on chemical measurements
Box & inbetween 2 CAD Modeling boxes and connectors
3 CCC Box cutting
Other 1 Principles & practices /
1 Project management Prepare planning and milestones
19 Project development /
20 Invention, IP, etc. /

Tasks Definition & Schedule

After analyzing where the various themes of the FabAC program fit in with my project, I decided to draw up a list of tasks and sub-tasks and distribute them in a schedule starting from the Midterm.

Tasks Definition

Tasks are divided by devices (HV Generator & Plasma Reactor).

HV Generator

The tasks concerning the high-voltage generator are defined below.

Plasma Reactor

The tasks concerning the plasma reactor are defined below.

Schedule

The schedule includes tasks and their distribution over time.

WeekTask
12Design of the PCB (iteration 2)
Testing the PCB (iteration 1)
13Manufacturing & Testing PCB (iteration2)
Testing HV Generator (iteration 1)
14Testing HV Generator (iteration 2)
15Design Plasma Reactor + Manufacturing Plasma Reactor (iteration 1)
16Testing Plasma Reactor (iteration 1)
17Design Manufacturing Plasma Reactor (iteration 2?)
18Testing Plasma Reactor (iteration 2)
19Testing Plasma Generation (plasma reactor + HV Generator)
Presentation Preparation (video)
20Project Presentation

Development

Project development was documented during week 18. The development followed the PDP methodology for Product Design Process.

Results

HV Generator

The final result of the generator is shown below. It can be controlled via the user interface accessible here.

HVGene_Res High Voltage Generator - Inside

HVGene_Res2 High Voltage Generator - Outside

Plasma Reactor

The final result of the plasma reactor is shown below.

PlasmaReac_Res Plasma Reactor - Outside

Final Setup

The final setup consists of a plasma reactor connected to a high-voltage generator and a gas supply. A computer with an interface is needed to control the high-voltage generator. A view of the setup is shown below.

FinalSetup Final Setup - From left to right : Low DC Power Supply, Plasma Reactor, HV Generator, Computer

Workflow

To switch on the plasma, you must :

To switch off the plasma, you can either :

Here are a few images of the setup in operation.

FinalSetup_Working
PlasmaWorking

Conclusion

In conclusion, the project successfully demonstrates the integration of multiple advanced technologies to develop an atmospheric plasma reactor for medical use. By combining 2D and 3D design, various fabrication processes, and electronics, the project not only highlights the practical applications of atmospheric plasma but also showcases the ability to create functional, innovative solutions within the Fab Lab environment. The results affirm the potential of atmospheric plasma technology in enhancing sterilization processes, contributing to advancements in medical safety and efficiency. Future work could expand on the feedback control systems and further optimize the reactor design for broader applications.

Appendix

Bill Of Materials

The BOM is available here.

License

To maintain control over the use of my work, I have selected the “Creative Commons Attribution - Non Commercial - CC-BY-NC” license. This license permits others to use, share, and adapt my work for non-commercial purposes while requiring attribution to me.

license

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