About

Medical grade oxygen is an essential component of respiratory therapy. Typically this is provided by industrial scale cryogenic oxygen concentrators. The COVID-19 pandemic has highlighted the existing need for medical oxygen in field hospital settings which have a variety of challenges that need to be overcome.

Human resources are be limited both medically and technically. Medical staff communicate in a variety of local languages and may have little experience. Staff to patient ratios are much higher than is acceptable in a fully equipped hospital. Technical support staff face challenges such as lack of training and basic maintenance equipment.

Field hospital settings may be urban or rural, with limited access to reliable electrical power. Environments such as high temperatures, high humidity and fine dust particles create engineering challenges.

Infrastructure and logistics create additional challenges which has raised the requirement to design a device that can be manufactured locally, along with sufficient documentation to present to local regulatory authorities. Medical device standards must be met and this project aims to meet regulatory requirements.

Download the presentation from PubInvCon 2021!

1.0 Introduction

1.0 Introduction 

1.1 Problem and Background

The COVID-19 pandemic has highlighted the existing need for medical oxygen in field hospital settings around the world. These settings create a variety of environmental, technical and social challenges that need to be overcome to deliver oxygen to communities everywhere.

1.2 Solution summary in simple terms

Ox is a rugged, open-source oxygen concentrator that is designed to be used in environments with high temperature and humidity, dust and power-supply disruptions.

1.3 Solution summary in technical terms

Oxygen is produced from room air using the pressure swing adsorption process. This process uses a series of pre-treatment steps to remove VOCs and moisture from the intake air, before it is passed through a molecular sieve made from synthetic zeolite. The zeolite adsorbs nitrogen, allowing oxygen to selectively pass through the sieve; the nitrogen is then purged to atmosphere. The resulting gas is 95% oxygen and 5% argon which can be used in respiratory therapies.

1.4 State of advancement of the project

A working prototype has been built (V1) which demonstrates proof of concept. Several shortcomings have been documented and improvements have been proposed. This grant application will allow for the implementation of such improvements.

1.5 Project Timeline

• Week 1: Create electronic circuit for a test harness - the ‘yoke’ - to gather detailed telemetry from the process
• Week 2: Change valves based on results from V1
• Week 3: Implement electronic flow control using proportional valve
• Week 4: Conduct testing of V2 prototype and gather telemetry data to optimise system
• Week 6: System optimisation and refinement
• Week 8: Report on V2 outcomes

2.0 Project Implementation

2.1 Solution

Ox is a medical device comprising of mechanical, electrical and software elements. The molecular sieves are made using two aluminium cylinders containing synthetic zeolite. Standard ¼” BSP fittings are used to connect to off the shelf industrial valves, fittings and tubing. Where needed, 3D printing is used to create custom components that are easily reproducible anywhere in the world.

Currently an ESP32 is used as the microcontroller, which gathers data from a number of pressure, temperature and flow sensors throughout the system and controls solenoid driver chips to switch pneumatic valves on and off to control the flow of gas. V2 will use an Arduino Mega to implement the core control system to allow for additional sensor inputs. The ESP32 will be used for secondary networking and display processing.

2.2 Methodology

Ox is built in a workshop that has been setup to mimic a simple maker space or automotive workshop, with the idea that Ox can be built and maintained anywhere with minimal resources. All mechanical components are made using entry-level metalworking skills or 3D printing. Ox uses open-source design software and the Arduino platform to enable anyone to contribute and implement the solution.

2.3 Results/Expected results

Ox aims to deliver 95% medical grade oxygen at 10LPM in a demanding environment. The resulting design files will allow for anyone to reproduce Ox for local testing and development. Future work will include building a user-friendly digital display and dust-proof enclosure.

3.0 Safety, quality assurance and regulation 

3.1 What steps have you taken to ensure your solution’s safety? How advanced are you in this process (if applicable)? Please check the Biosafety and Biosecurity guideline of OpenCovid19

Throughout development standard health and safety practices have been followed such as wearing safety glasses and dust masks. Concentrated oxygen is highly flammable and all testing is done is a well ventilated space with emergency shut offs and fire fighting equipment available.

3.2 Have you planned the conduct of your manufacturing process that ensures quality, what are the steps you have taken? How advanced are you in this (if applicable)?

Ox is in the design and prototyping stage. Consideration for local batch-manufacturing is given at each step in the design, primarily through lathes, mills, 3D printing and online PCB manufacturing services. Some consideration is given to adapting Ox for manufacturing at scale. Ox is designed to be easily serviceable to ensure a long service life.

3.3 Will you need assistance with the regulation system? If not, which regulatory system do you plan on using to distribute the product? Please elaborate (please see: Regulatory-Strategies) (if applicable)

Ox aims to produce regulatory documentation to enable future partners to manufacture locally. Initial focus has been on R&D, although consideration has been given to FMEA and ISO compliance during this time. Ox will use VentOS as the software, which has extensive regulatory documentation. Materials used in the construction of Ox are oxygen compatible.

3.4 Have you talked to medical staff about the feasibility of your project? What did they say? 

Yes - oxygen concentrators could have a positive impact for COVID-19, especially as no highly-trained staff or medications are required. Current commercial oxygen concentrators are not designed to be rugged, leading to a reduced service life.

3.5 Have you planned the testing, verification and validation of your solution? How advanced are you? (if applicable)

A prototype has been built and tested using the open source tool, VentMon. In the future, lab testing such as gas chromatography would be required to demonstrate that Ox produces medical grade oxygen. Telemetry would provide additional data about the system.

4.0 Impact, issues and risks

4.1 What impact do you feel your project could have?

Ox could have a high impact to provide medical oxygen for remote communities for COVID-19 and beyond, eg. childhood pneumonia, asthma, COPD.

4.2 What do you think would make your project a success?

Manufacturing and deploying Ox to communities around the world.

4.3 Please list the known issues, potential risks, grey-areas, etc in your project

Developing a reliable and reproducible system is a challenge, however risks are mitigated with a systematic engineering approach.

5.0 Originality

5.1 What other projects on JOGL are like yours?

There are no other oxygen concentrators on JOGL.

5.2 Is this an innovative project? What makes this project different if it’s unique on JOGL?

Ox is unique in aiming to create a rugged oxygen concentrator that current commercial products are not suitable for.

5.3 Is there already an open source version of this project?

There are several open source oxygen concentrators, however Ox aims to be rugged, easy to use and locally made.

6.0 Team experience

6.1 Please cite your team members and their roles in the project. 

Ben Coombs

Ben is the lead engineer on this project and Public Invention Coach. He is an experienced engineer having developed electronic, software and mechanical projects and has been involved in COVID initiatives since the start of the pandemic, such as VentMon and VentOS. Ben holds a Master of Engineering in manufacturing aerospace materials. Ben's lab is in New Zealand with metalworking, welding, 3D printing and electronic fabrication.

Public Invention is a group of inventors working “in the public, for the public”. Public Invention Ox collaborates across the open source community and shares all work under the GNU license.

7.0 Funding and Costs

7.1 Please provide a costing of your project be as detailed as you can, all funding requests must be transparent and be for specific needs.

This grant would enable a second prototype to be built.

7.2 How is your project being funded so far?

Currently funded by Public Invention.

7.3 How much funding do you need and how do you plan to use that funding?

To achieve the building of the next prototype:

• Electronics: 450
• Valves and fittings: 550
• Mechanical: 400
• 3D printing: 350

Total: 1750 Euro